Atlas-of-Neurosurgical-Techniques-Spine-and-Peripheral-Nerves

942
Peripheral Nerve: BrachialPlexus
~----
/
l
--~
.....
A
...--
=='\
8
..",..-----
"
"
,-.....
Figure128-3
(A) Exposureofthe distal ulnarinthe region ofGuyon'scanal employsa curvilinearincisioncentered just medial to the pisiform.
(8) Thenerve has a relativelysuperficialcourse and travelswith the ulnarartery forthe distalthird ofthe forearm. The site ofcompressioniscom-
monly as the nerve enters the hand between the hamate and the pisiform.
fascial,containing the nerve and preventing slippage of the
nerve overthe bonyprominence of the medial epicondyle.7
Exposure to the nerve in the forearm requires the exten-
sion of the incision onto the volar forearm, again avoiding
injury to the antebrachial cutaneous nerve. The ulnar nerve
is found between the flexor digitorum superficialis and the
flexor carpi ulnaris and alongside the deep flexors.
Exposure of the nerve at the wrist can be made by ex-
tending this incision toward the radial aspect of the hamate
(Fig. 128-3A). Or a more limited exposure of the regionof
Guyon's canal can be made by locating the pisiform andthe
hamate bone (Fig. 128-38). These bony prominences are
the landmarks to locating the incision properly. AlazySin-
cision over the wrist reduces flexion contractures. TheneIVe
will be identified just alongside the ulnar artery deeptothe
volar carpal ligament. Careful inspection will ensure the
complete division of the pisiohamate and pisiometacarpal
ligaments.

References
128
Radialand Ulnar Nerve
943
1. Seigle I DB.Gelberman
RH. Radial nerve: applied
anatomy
and opera-
tive exposure.
In: Gelberman
RH. ed. Operative
Nerve Repair and Re-
construction.
Philadelphia:
Lippincott;
1991 :393-407
2. Henry AK. The upper
arm. In: Henry AK. Extensile
Exposure.
2nd ed.
New York: Churchill Livingstone;
1973:91-115
3.
Pirela-Crux MA. Orner GE. Benzel EC.Surgical exposure
of the periph-
eral nerves
of the upper
extremity.
In: Benzel EC. ed. Neurosurgical
Topics: Practical Approaches
to Peripheral
Nerve Surgery. Park Ridge.
IL:AANSPublications
Office; 1992:313-152
4.
Dellon AL. Mackinnon
SE. Radial sensory
nerve entrapment
in the
forearm.j
Hand Surg [Am] 1986;11 :199-205
5.
Kline DG. Hudson AR.Ulnar nerve surgical anatomy. In: Kline DG. Hud-
son AR.eds. Nerve Injuries: Operative
Results for Major Nerve Injuries.
Entrapments
and Tumors. Philadelphia:
WB Saunders;
1995:238-241
6.
Seigle I DB. Gelberman
RH. Ulnar nerve:
applied
anatomy
and opera-
tive exposure.
In: Gelberman
RH. ed. Operative
Nerve Repair and Re-
construction.
Philadelphia:
Lippincott;
1991 :413-423
7.
Laha RK. Panchal
PD. Surgical
treatment
of ulnar
neuropathy.
Surg
NeuroI1979;11:393-398

129
Trauma to the Lumbosacral Plexus
Yong-JunCho, Daniel H. Kim, and David G. Kline
. Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
Objectives
.
Anatomy
Lumbar
Plexus
Sacral Plexus
Lumbosacral plexus injury is a relatively rare clinical entity
that usually results in severe neurological deficit. In addi-
tion to gunshot wounds (GSW) and other penetrating in-
juries to the pelvic region, fractures of the pelvis and of the
sacrum provide the usual cause.I-4 However, iatrogenic in-
jury usually associated with tumor excision and other
pelvicprocedures has been reported.s
Clinicalpresentation of lumbosacral plexopathy includes
motor and sensory deficit in the distribution of multiple
nerves originating from this plexus; the sciatic, femoral. ob-
turator, and superior and inferior gluteal nerves.
Operation on the lumbosacral plexus is especially diffi-
cult. The lumbar plexus is usually approached by a flank
muscle-splitting
retroperitoneal
approach.
The sacral
plexus is usually exposed with the help of a general or gy-
necological surgeon by a trans peritoneal route. Surgical re-
sults are generally acceptable for lumbar plexus outflows,
but poor for those of the sacral plexus.
.
Indications
. Tractioninjury(motorcycle,automobile,sports,or work
related)
. Stab/laceration(sharpknifeorglass)
.
Contusiveinjury(secondaryto hipor pelvicfracture)
.
Penetratinginjuries(GSW,metalfragments)
.
Compressioninjury
.
Iatrogenicinjury(abdominaland gynecologicalsurgery)
. Radiationinjury
944
.
Surgical Technique
Anesthesia
Lumbar Plexus Exposure
Sacral Plexus Exposure
Donor Nerve Graft Harvesting
.
Surgical Repair
Intraoperative
Nerve Action Potential Recording
Decompression/Neurolysis
Suture Repair
Graft Repair
.
Contraindications
. Lumbosacral plexitis
. Transient compressive plexopathy (secondaryto
pregnancy)
. Transientradiationplexopathy
.
Multiplepseudomeningoceleon myelogram
.
Advantages
. Surgical results for lumbar plexus outflows are accept-
able.
.
Disadvantages
. Operationon the lumbosacralplexus is especially
difficult.
. Surgicalresultsarepoorforthesacralplexus.
.
Objectives
To expose and obtain direct access to the lumbosacral
plexus,includingtheir majorbranches.to performneuroly-
sis, direct end-to-end suture, or graft repairs

129
Trauma to the Lumbosacral Plexus
945
. Anatomy
roots of L1through L4. L1may receive a communication
from T12, the subcostal nerve. The L4spinal nerve of the
lumbosacral
plexus contributes
to the
sacral plexus
through the lumbosacral trunk, as do all of L5 and the
individual primary rami of 51, 52, 53, and a portion of
54, which
also contributes
to the
coccygeal
plexus
(Fig. 129-1).
Themain nerves of the pelvis and lower limbs arise from
the lumbosacral
plexus.
This lumbosacral
plexus
is
formed by contributions from roots T12 to 55.The lumbar
portion of the plexus originates from the ventral primary
rami, which are formed in turn by the spinal nerves or
A
Figure 129-1
Overview anatomy of the lumbosacral plexus and major
branches. (A)The lumbosacral plexus with relationship to the lumbar spine
and pelvis.(8) Thesciaticnervewith relationshipto the lumbarspine.
B

Lumbar
Plexus
946
PeripheralNerve:Pathologyof the LumbosacralPlexus
The lumbar plexus is formed by anastomosis of the ventral
rami of the first four lumbar nerves. The lumbar plexus
spinal nerves are located in the posterior portion of the
psoas major and in front of the transverse processes of the
vertebrae. Numerous collateral and terminal branches arise
from the lumbar plexus.
1. The iliohypogastric and ilioinguinal nerves arise from
the first lumbar nerve. The iliohypogastric nerve passes
through the psoas muscle and anterior to the quadratus
lumborum to reach the area superior to the iliac crest.
The ilioinguinal nerve is smaller than the iliohypogas-
tric nerve. It circles the trunk just below the iliohy-
pogastric, and laterally is located between the trans-
verse and internal oblique muscles.
2. The genitofemoral nerve arises from the first and sec-
ond lumbar nerves. It emerges on the anterior aspect of
the psoas muscle opposite the third or fourth lumbar
vertebra and runs within the fascia iIiaca behind the
ureter and peritoneum.
3. The femoral nerve is the largest terminal branch and
arises from the dorsal branches of the ventral rami of
the second, third, and fourth lumbar nerves. It courses
for 8 to 10 cm within the pelvis in a retroperitoneal po-
sition, descends through the posterior part of the psoas
muscle, and emerges from the lateral border of the mus-
cle opposite the fifth lumbar of the first sacral vertebra.
4. The lateral femoral cutaneous nerve arises from the
second and third lumbar nerves. It penetrates
the
psoas, crosses the iliacus, and, at the level of the ante-
rior superior spine of the ilium, courses downward be-
tween the attachments of the inguinal ligament.
5. The obturator
nerve
originates
from the
ventral
branches of the ventral rami of L2,L3,and L4.It reaches
the medial border of the psoas, travels below or deep to
the iliac vessels, and takes a vertical course toward the
obturator foramen.
6. The lumbosacral trunk is made up of the smaller part of
the fourth nerve and the fifth lumbar nerve and is an el-
ement in the foramen of the sacral plexus. The trunk is
located medial to the psoas major muscle; it descends
in front of the lateral part of S1 and the sacroiliac joint
and then joins the first sacral nerve.
Sacral Plexus
The sacral plexus is formed by the lumbosacral trunk and
the ventral rami of the first, second, third, and fourth sacral
nerve. The sacral plexus lies deep and medial in the pelvis,
overlying the sacroiliac and sacrococcygeal junctions.
Plexus nerves exit the pelvis, for the most part, by the
greater sciatic foramen (sciatic, hamstring, gluteal, and pos-
terior cutaneous nerves), whereas the pudendal reaches the
perineum through the lesser sciatic foramen. The gluteal
vessels follow the same course as the sacral nerves.
1. The sciatic nerve is formed from the ventral and dorsal
rami of the L4,LS,S1,and S2spinal roots, as well as the
ventral rami of S3. It is the largest nerve in the body.
The commencement
of the sciatic nerve is located
opposite the greater sciatic foramen in front ofthepiri-
form muscle. It leaves the pelvic cavity throughthe
greater sciatic foramen, below the piriform muscle,and
passes behind the sacrospinalligament at its insertion
on the ischiadic spine. The inferior gluteal nerveand
artery are adjacent to the sciatic nerve.
2. The pudendal nerve derives from the second,third,and
fourth sacral nerves. This nerve exits the pelvisthrough
the greater sciatic foramen between the piriformisand
coccygeus muscles and lies on the sacrospinousliga-
ment. Branches include the inferior rectal and perineal
nerve and dorsal nerve of the penis or clitoris.
.
SurgicalTechnique
Anesthesia
General anesthesia
is essential.
The neuromuscular
block-
ade used for induction must wear offduring the earlyphase
of the dissection
so that intraoperative
electrical recording
of the effects of muscle contraction
from stimulation canbe
tested. Localanesthetic should be avoided due to the possi-
bility of nerve conduction
block, which may cause errorsin
recording intraoperative
nerve action.
LumbarPlexusExposure
The lumbar
plexus
can
be
approached
by a nank
muscle-splitting
procedure. The patient is placed inapar-
tiallateral decubitus position with a roll or support under
the flank to be opened. Skin and subcutaneous tissuesare
opened in the lateral flank with an oblique incisionbegin-
ning beneath the lateral rib cage and extending inferiorly
toward the anterior iliac crest or midportion ofthe inguinal
ligament (Fig.129-2). The external and internaloblique
muscles are split in the direction of their fibers, as isthe
transversalis muscle. The peritoneum is dissectedaway
from the retroperitoneal fat, and the retroperitoneal space
is dissected by the gloved fingers or a sponge stickuntilthe
iliopsoas is located. ADeaver or similar ribbon-shapedre-
tractor is used to retract the abdominal contents andhelp
develop the retroperitoneal space. The anterior surfaceof
the vertebral column lies midline and medial to the iliop-
soas as the latter originates from the transverse processes.
Spinal nerves penetrate through some of the psoastoform
the upper lumbar plexus and, further distally, the femoral
nerve (Fig.129-3). Bydissecting over the psoas muscleand
developing the space along the lateral lumbar vertebrae,the
sympathetic chain can be identified. Somewhat beneaththe
lateral border of the psoas, spinal nerves L2,L3,andL4,
which give rise to the femoral nerve and other branchesof
the lumbar plexus, can be identified.
Sacral Plexus Exposure
The sacrum tilts away vertically from the surgical access,
which makes this exploration very difficult. The sacral

129
Traumato the LumbosacralPlexus
947
A
B
Figure129-2
Skinincisionfor a flankmuscle-
splitting procedure.
c
Figure129-3
Retroperitoneal surgical approaches. (A) Skin
incision. (B) Superficial dissection. (e) Deep dissection.

948
PeripheralNerve:Pathologyof the LumbosacralPlexus
plexus exposures require help from a general surgeon or a
gynecologist by a transperitoneal route. Descending colon
and sometimes the peritoneal reflection of the rectum need
mobilization. Ureter,as well as iliacvessels, need to be iden-
tified and protected. Such pelvic surgery requires one to
work with those familiar with the structures, as well as the
steps necessary to expose and those needed to protect them.
During the exploration, the sciatic nerve is readily visual-
ized and the sciatic foramen along with the sciatic nerve can
be explored to its intrapelvic beginning. The nerve is formed
on the anterior surface of the piriformis, where the sciatic
nerve isvisible to the surgeon operating from a conventional
posterior route. By incising the piriformis and trimming
away part of the bone of the notch area, the surgeon is able
to reach the point in the pelvis through the posterior route.
If the surgeon needs to work more medially on the sciatic
nerve and spinal nerves, the approach is through the pelvis.
where the surgeon has to work more in the relatively
cramped quarters of the true pelvis. The peritoneal reflec-
tion for the rectum is medial, and for a pelvic approach,
large branches of the internal iliac veins have to be con-
trolled as the spinal nerves of 51,52, and 53 are exposed.
Donor Nerve Graft Harvesting
Because of the supine position of the patient, sural nerve
exposure is more difficult. Knee flexion and a folded sheet
under the buttock help the surgeon internally rotate the leg
a bit to expose the calf.The incision is made in a curvilinear
fashion on the posterior calf, extending to the lateral ankle
region. The entire length of the sural nerve can be har-
vested. Anaverage of 25 to 35 cm length of the sural nerve
can be harvested from each leg.
. SurgicalRepair
Intraoperative
Nerve Action Potential Recording
Intraoperative recording of nerve action potentials (NAPs)
provides the best assessment of residual and/or regenera-
tive nerve function in cases of injury. NAPsmay be recorded
from whole nerve or from individual fascicles or groups of
fascicles.The presence of a NAPbeyond all damage sites in-
dicates reserved axonal function or significant axonal re-
generation, which predicts well for functional recovery. By
comparison, the absence of a NAPhas been correlated his-
tologicallywith neurotmesis, which suggests inadequate re-
generation and poor functional recovery. NAPrecording can
show regenerative changes across a lesion in continuity as
early as 6 to 8 weeks after focal injury; thus NAPscan pro-
vide useful information earlier than clinical examination or
standard electrodiagnostic studies.
Decompression/Neurolysis
Neurolysis is generally performed by freeing up a more
normal segment of nerve proximal and distal to the site of
scarring and alternatively
working toward the injured seg-
ment in a circumferential fashion around the nerve.This
can usually be done with a no. 15 scalpel blade or some-
times more readily by a pair of Metzenbaum scissorswith
magnifying
surgicalloupe
or microscope. Dissection iscar-
ried from the areas of healthy
tissue to less healthy areas
and beyond. Potential areas of entrapment
are released.
After neurolysis
has been completed,
stimulating and
recording
electrodes
are placed on the nerve, proximalto
the level of the lesion. Stimulation should produce a record-
able NAP above or proximal
to the lesion. The recording
electrodes
are then moved into the region of the injury,and
changes in the evoked NAPare noted. Recording electrodes
are then moved distally to see if a response is transmitted
beyond the lesion in continuity.
Suture Repair
Once an element is interpreted to be electricallysilentand
when a short nervegapexists,end to endepineurialrepair
is recommended.
Sharp dissection is necessary to free
stumps from adjacent and scarred soft tissues. Stumpsare
then trimmed back to healthy epineurium and fascicular
structure. Distal neuroma is resected back to a discernible
fascicular pattern. Repair is done by first placingtwolateral
sutures, usually 6-0 in caliber, at the 3 o'clockand9o'clock
positions. After the lateral sutures are tied, their endsare
clamped with a fine hemostat and the lateral edgesare
spread somewhat so that there is a clear delineationofthe
proximal and distal intervening epineurial edges.Thelat-
eral sutures are then rotated to expose the backsideofthe
repair site. This side is then closed by several finelyspaced
sutures.
Graft Repair
When the gap is too great for end-to-end
repair, autografts
are harvested and a grouped interfascicular graft is done.
This is often necessary for lesions in continuity ofmoderate
or more length and with unrecordable
NAPs.This isalsonec-
essary with transected nerves when the stumps havere-
tracted
and
cannot
be
approximated
without
tension.
Epineurium
from each stump
is trimmed,
and then each
stump end is split into multiple
bundles
or fingers of fasci-
culi. Similarly disposed ends or tails are then created onthe
opposite
stump.
Interfascicular
epineurial
tissue or scaris
then trimmed
from between
the fasciculi or groups offasci-
culi. If neuroma
in continuity
is encountered,
NAPacrossthe
lesion is recorded. If NAPcannot be measured
across thele-
sion, a sharp no. 15 blade is used to cut the injured segment
until healthy-appearing
fascicles on the cross sections are
observed
in both proximal
and distal segments. The gapis
then measured,
and the number of grafts necessary to close
it is calculated. Sural nerve is harvested
and sectioned proxi-
mally and distally after the desired length is dissected free.
Donor nerve is then divided into segments
-10% longerthan
the gap to be closed. Each graft end is secured with several
6-0 or 8-0 Prolene sutures.

References
129
Traumato the LumbosacralPlexus
949
1. FasslerPR,Swiontkowski
MF. Kilroy AW, et al. Injury
of the sciatic
nerveassociated with acetabular fracture.J BoneJoint Surg Am 1993;
75:1157-1166
2. Kline DG. Operative
management
of major
lesions of the lower
extremity. Surg Clin North Am 1972;52:1247-1265
3. Kline DG. Hudson AR. Nerve Injuries:
Operative Results for Major
Nerve Injuries.
Entrapments,
and
Tumors.
Philadelphia:
WB
Saunders;1995
4.
Kline DG. Kim DH, Midha R. et al. Management
and results of sciatic
nerve injuries: a 24-year experience. J Neurosurg 1998;89:13-23
5.
Edwards BN.Tullos HS.Noble Pc. Contributory
factors and etiology of
sciatic nerve palsy in total hip arthroplasty.
Clin Orthop 1987;218:
136-141

130
Tumors of the Lumbosacral Plexus
Yong-Jun Cho, Daniel H. Kim, and David G. Kline
.
Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
Objectives
Tumors of the lumbosacral plexus are relatively uncommon.
The natural history of these tumors is unpredictable and the
preferred method of management for patients is not well
described.I-3 It is at times difficult to decide on appropriate
therapy for patients with these lesions because of this un-
predictability. Their management requires knowledge of the
characteristics of the tumor as well as the regional anatomy
of the pelvicregion.
Neurofibromas are the most commonly encountered be-
nign lumbosacral plexus tumors of neural sheath origin,
and schwannomas are the next.l,4The lumbosacral plexus
also may be invaded by the malignant tumors of the pelvic
organs. Locally invasive colorectal carcinoma is the most
common cause of neoplastic lumbosacral plexus lesion.
.
Indications
. Schwannomas
. Neurofibromas
.
Othertumorsofneuralsheathorigin
.
Intrapelvic tumors infiltrated into the lumbosacral
plexus
.
Contraindications
.
Intrapelvic tumors with extensive invasion
.
Advantages
. Schwannomas are generally resectable in their entirety
without neurological sequelae.
950
. Anatomy
.
Surgical Technique
Anesthesia and Positioning
Incision and Dissection
Donor Nerve Graft Harvesting
.
SurgicalRepair
.
Disadvantages
. The sacral plexus exposure is difficult; helpisrequired
from surgical colleagues.
.
Objectives
To expose and obtain direct access to the lumbosacral
plexus, including their major branches, to resecttumorand
restore
normal
function
. Anatomy
Basic anatomy
of the lumbosacral
plexus area has beende-
scribed in Chapter 129.
.
Surgical Technique
Anesthesia and Positioning
General anesthesia
is essential.
In case of the sacral plexus
exposure for pelvic tumors, the surgeon shouldrequirehelp
from a general
surgeon
or a gynecologist.
Preoperatively.
the surgeon needs to advise the anesthetist
that the neuro-
muscular
blockade used in induction
must wear offduring
the early phase of the dissection so that intraoperativeelec-
trical recording, as well as the effects of appropriate muscle
contraction
from the stimulation, may be tested. Local
anesthetic
should be avoided due to the possibility ofnerve
conduction
block, which
may cause errors in recording
intraoperative
nerve action.

...
130
Tumors of the Lumbosacral Plexus
951
The patient is placed on the operating table in a supine
position. Knee flexion facilitates harvesting both sural
nervesand ipsilateral common peroneal nerve for grafts if
needed for nerve grafting. The entire abdomen, chest, and
lowerextremities should be prepped and draped free.
Incisionand Dissection
Becaus~most lumbosacral plexus tumors usually grow over
15cm in the largest dimension and tend to grow anteriorly
andobscuring the location of intact pelvic plexus elements
that lie behind them, a transabdominal approach is recom-
mended(Fig.130-1).
Schwannomas are generally resectable and should be ap-
proached with the intent of complete extirpation. Benign
tumorswith gross characteristics of schwannoma should be
resected without neurological sequelae (Fig. 130-2). It is
possible to remove a schwannoma by peeling the nerve
from the tumor itself in a "bucket-handle" fashion (Fig.
130-3).
Apotential form of treatment for neurofibromas is intra-
capsularenucleation. This may be a necessary initial step in
excision of very large tumors, but in smaller tumors the
treatment is likely to leave fragments behind.
The gross distinguishing factor between neurofibromas
andschwannomas during an operation is the tendency of
neurofibromas to have more fascicles entering and exiting
the substance of the tumor at its poles or to have one rela-
tivelylarge contributing and exiting fascicle. Schwannomas
arenoted to have fascicles that run within the capsule but
areunlikely to have intra tumoral fascicles of significance,
although these occur in the superficial layers of very large
tumors.
Theneuroforaminal region in the lumbosacral spine and
thetissues just lateral to it are a "no man's land." The surgi-
calexposure of the proximal neuroforamina is straightfor-
wardvia a laminectomy. The distal neuroforamina, how-
ever,is nearly impossible to reach without an extensive
retroperitonealdissection.
Well-defined intrapelvic tumors with radiculopthy and/or
mass effect require resection via an infra- or intraperitoneal
approach. Apfannensteil incision and a retroperitoneal ex-
posure may be appropriate.
Some other tumors of neural sheath origin in the pelvis
are exceptionally large and require extensive exposure of
pelvic contents, including mobilization of bowel, identifica-
tion of ureters, and as much protection of aortoiliac vessels
and plexus nerves as possible. For these cases, help from a
general surgeon or sometimes a gynecological surgeon is
required to provide the initial exposure and to mobilize ab-
dominal contents. Ifthe sacral plexus or deep pelvis is to be
explored, a transabdominal
approach
is favored, even
though a lateral muscle-splitting approach similar to that
used for trauma to the lumbar sacral plexus (see Chapter
129) is also available if the lesion involves lumbar rather
than sacral area.
At exploration, the tumor and the nerve fascicles proxi-
mal and distal to the tumor should be dissected. The usual
finding is of a tumor growing within the substance of the
nerve with uninvolved fascicles splayed circumferentially
around the center of the mass. With a microsurgical
technique, these fascicles are gently dissected free of the
tumor in the extracapsular
plane. As the tumor is thus
gradually exposed and the proximal and distal poles are
approached, care should be taken to isolate fascicles enter-
ing either the substance of the tumor or its capsule. A
common finding in the case of either neurofibromas or
schwannomas is of one or more fascicles running between
the leaves of the capsule of the tumor but not entering the
tumor proper. Occasionally, when it is considered helpful
to debulk large tumors to simplify subsequent dissection,
a longitudinal incision should be made in the capsule be-
tween fascicles.
Donor Nerve Graft Harvesting
The most common source of donor nerve grafts is the sural
nerves from both lower extremities. Knee flexion and a
Figure 130-1
Transverselongincisionmarking
on the fower abdomen for the transabdominaf
approach to the pelvicplexus.

952
Peripheral Nerve: Pathology of the Lumbosacral Plexus
Figure 130-2
Apelvicplexustumor. (A)Magneticresonance imag-
ing ofthe pelvisdemonstrating a pelvicplexustumor. (B)The tumor
afterdissectionfromthe plexus.
folded sheet under the buttock help the surgeon internally
rotate the leg a bit to expose the calf. The incision is made
in a curvilinear fashion on the posterior calf, extending to
the lateral ankle region. The entire length of the sural nerve
can be harvested. An average of 25 to 35 cm length of sural
nerve can be harvested from each leg.
.
Surgical Repair
Intraoperative nerve action potential (NAP)should be per-
formed, usually both prior to and following excision of the
lesion. Exceptions to this rule are permitted in the cases of
References
1.
Benzel EC.Morris DM, Fowler MR. Nerve sheath
tumors
of the sciatic
nerve and sacral plexus.J Surg OncoI1988:39:8-16
2.
Kline DG, Hudson
AR. Nerve Injuries:
Operative
Results
for Major
Nerve Injuries.
Entrapments.
and Tumors.
Philadelphia:
WB Saun-
ders: 1995
Figure 130-3
Problems of removing neural sheath tumors (schwan.
noma, neurofibroma, and plexiform neurofibroma). Drawingshows
the usual appearance of a schwannoma
(top), a solitary nerurofibroma
(middle), and a plexiform neurofibroma
(bottom).
(With permission
from DonnerTR, Voorhies RM,Kline DG. Neural sheath tumorsofma.
jor nerves. J Neurosurg 1994:81 :362-373.)
extremely
large pelvic or presacral
tumors
in which proxi-
mal or distal nerve trunks cannot be identified prior toexci-
sion of the mass. When the status of any fascicle or groupof
fascicles referable to the tumor is in doubt, they havetobe
tested
by NAP studies.
If the NAP recordings
from capsular
fascicles give a positive response, these fascicles shouldbe
spared. When necessary, nerve grafting is performed, usu-
ally for repair of nerve injuries that have occurred during
operations.
Methods of neurolysis, direct end-to-end
suture, and
graft repair have been described in Chapter 129.
3.
Robertson JH, Gropper GR. Dalrymple S. et al. Sacral plexus nerve
sheath
tumor:
case report. Neurosurgery
1983:13:78-81
4.
Donner
TR. Voorhies
RM. Kline DG. Neural sheath
tumors of major
nerves. J Neurosurg
1994:81 :362-373

131
Approach to Nerves of the Lower Extremity
AllanH. Friedman
.
Indications
.
Lateral Femoral Cutaneous Nerve
. FemoralNerve
. TheObturator Nerve
Exposureof the Obturator Nerveinthe Thigh
.
The Sciatic Nerve
.
Exploration of the Intrapelvic Sciatic Nerve
.
Exposure of the Proximal Extrapelvic Sciatic Nerve
.
Exposure of the Tibial Nerve in the Leg
.
Exposure of the Tibial Nerve in the Ankle
.
Peroneal Nerve
.
Exposure of the Common Peroneal Nerve at the Knee
.
Exposure of the Superficial Peroneal Nerve
.
Exposure of the Deep Peroneal Nerve at the Ankle
Thenerves of the lower extremity are the "neglected step-
sister" of the nerves of the upper extremity. Nerve entrap-
ment syndromes of the lower extremity are lesswell appre-
ciatedand nerve injuries in the lower extremity are thought
to have a poorer prognosis. Recent publications by Kline
andothers have demonstrated
that repair of the nerves in
thelower extremity can be rewarding.I-3
This chapter discusses the anatomy and surgical exposure
of the nerves in the lower extremity. The clinical aspects of
nerveentrapment syndrome and the techniques of periph-
eralnerve repair are not discussed.
.
Indications
.
Injury to nerve: partial or complete transaction or injury
in continuity
. Tumor:benign or malignant
.
Entrapment
syndrome
.
Lateral Femoral Cutaneous Nerve
The lateral femoral cutaneous
nerve originates
most
frequently from the ventral rami of the secondand third
lumbar nerve roots. After emerging from behind the psoas
muscle the nerve lies on the iliacus muscle, passing just un-
der the pelvic brim to exit under the inguinal ligament and
over the sartorius muscle4approximately one fingerbreadth
medial to the anterior superior iliac spine (Figs. 131-1 and
131-2).Thenervemayrun throughthe inguinalligamentor
through the attachment of the sartorius muscle. Rarely,the
nerve may run over the top of the anterior superior iliac
spine. In the upper thigh the nerve travels in a tunnel
withinthe deepfascia.Approximately5 cmbeyondthe iliac
crest it divides into an anterior and a posterior branch, both
of whichpiercethe fascialata,-10 cmdistalto the inguinal
ligament.
Exposureof the lateral femoralcutaneous nerve in the
pelvis is rarely indicated. When lateral femoral cutaneous
nervemuscleisfoundinthe pelvisit is exposedbyopening
953

954
Peripheral Nerve: lumbosacral Plexus
Iliacus muscle
Femoral nerve
Tensor fasciae
latae muscle
Sartorius
muscle
Rectus femoris
muscle
Vastus latera/is
muscle
Lateral cutaneous
nerve of thigh
Iliacus muscle
Femoral nerve
Tensor fasciae
latae muscle
Sartorius
muscle
Rectus femoris
muscle
Vastus lateralis
muscle
Adductor brevis
muscle
Psoas major muscle
Femoral artery
and vein
Inguinal ligament
Adductor longus
muscle
Figure 131-1
The lateralfemoral cutaneous nervetrav.
els under the iliacus fascia just beneath
the pelvic brim
emerging over the medial border of the sartorius muscle.
The obturator nerve travels lateral to the internaliliacves-
sel. The anterior branch of the obturator
nerve travels be-
hind the pectineus
and adductor
longus muscles and in
front of the adductor
brevis and longus. The posterior
branch of the obturator
nerve travels behind the adductor
brevis.
Figure 131-2
The lateral femoral cutaneous nerveexits
under the inguinal ligament and travels over the sartorius
muscle in a tunnel in the deep fascia. The femoral nerve
emerges from within the psoas muscle and passesunder
the inguinal ligament lateral to the femoral artery.

131
Approachto Nervesof the lower Extremity
955
theabdominalwall along the anterior pelvis brim. The lateral
femoralcutaneous nerve is found lying on the iliacus muscle
lateralto the femoral nerve beneath the iliacfascia.
Mostfrequently the surgeon is interested in identifying
thenerve as it passes under the inguinal ligament. Be-
causeit is often difficult to find the nerve at the level of
theinguinal ligament, the nerve is best identified 2 or
3in.beyond the ligament by opening the deep fascia over
thesartorius muscle. Abranch of the lateral femoral cuta-
neousnerve identified at this level can be followed proxi-
mallyby the surgeon to the tunnel under the inguinal
ligament.
. FemoralNerve
Thefemoral nerve is formed in the substance of the psoas
musclefrom the dorsal portion of the ventral rami of the
second,third, and fourth lumbar nerve roots. The nerve
emergesfrom the psoas major muscle at the pelvic brim
andtravels in the groove between that muscle and the ilia-
cusmuscle under the cover of the iliac fascia (Fig. 131-2).
Thefemoral nerve enters the thigh from under the inguinal
ligamentlateral to the femoral artery. Prior to reaching the
inguinalligament the sensory fibers migrate anteriorly and
themotor fibers migrate posteriorly within the nerve. At
the level of the ligament a small branch innervates the
pectineus muscle. One to 2 in. distal to the ligament the
nervedivides into anterior and posterior divisions, which
quicklysubdivide into the terminal branches of the femoral
nerve.5
Theanterior division innervates the sartorius muscle and
providessensation to the anterior thigh as far distally as the
kneethrough the medial cutaneous nerve and the interme-
diatecutaneous nerve.
Theposterior division innervates the quadriceps femoralis
musclethrough a splay of branches and gives origin to the
saphenous nerve. The saphenous
nerve is the longest
branchof the femoral nerve providing sensation to the me-
dialleg. The saphenous nerve passes behind the sartorius
musclewhere it travels with the femoral artery in the ad-
ductorcanal. The saphenus nerve gives rise to the infrap-
ateliar branch, which pierces the tendon of the sartorius
muscle to innervate the skin just below the knee. The
saphenous nerve then passes between the tendons of the
gracilisand sartorius muscles, entering the subcutaneous
tissueand innervating the medial leg to the medial malleo-
lusand the top of the medial foot, extending toward the
largetoe. In the distal third of the leg the saphenous nerve
bifurcates into two terminal branches, one paralleling the
medialtibia to the malleolus and the second passing ante-
riorto the malleolus and continuing over the medial foot.
Throughout its subcutaneous course the saphenous nerve is
intimately related to the saphenous vein.
The femoral nerve can be exposed from its appearance at
the edge of the psoas muscle to its exit under the unguinal
ligament through an anterior lateral extra peritoneal ap-
proach (Fig. 131-3). Askin incision is made just above and
parallel to the iliac crest, and the abdominal wall is opened
in layers exposing the pre- and retroperitoneal fat. It is wise
to tack the edges of the cut muscle layers so that they can
be reapproximated at the time of closure. Retracting the
peritoneal contents anteriorly will readily expose the lateral
femoral cutaneous and femoral nerves, which lie under the
iliac fascia and the branches of the genitofemoral nerves as
they perforate the psoas muscle. This exposure can be ex-
tended anteriorly to expose the femoral nerve in the thigh.
Ifthe inguinal ligament is severed in the exposure, the liga-
ment's ends should be tacked so that they can be reapproxi-
mated at the end of the operation.
Several modifications of this approach have been de-
scribed that offer a better exposure of the more proximal
intrapsoas portion of the femoral nerve; the upper lumbar
roots, which form the femoral nerve; or the proximal
lower lumbar roots, which contribute to the sciatic nerve.
More proximal exposure of the upper lumbar plexus is
achieved by an incision that begins just below the lateral
rib cage and extends transversely to just below the umbili-
cus. The external oblique muscle is split and the deeper
abdominal wall layers are cut. Again the peritoneal con-
tents are swept forward, allowing the upper lumbar roots
to be traced through the psoas muscle to their exit from
the spine. Dissection within the psoas muscle is facilitated
by flexing the hip releasing the tension on that muscle. In
males care should be taken not to injure the sympathetic
chain, which lies in the gutter between the psoas muscle
and the vertebral body, because this can result in retro-
grade ejaculation.
The femoral nerve can be exposed in the thigh by a verti-
cal incision made parallel and lateral to the femoral artery.
The incision can be carried as far distally as is necessary.
Proximal exposure of the femoral nerve is obtained by curv-
ing the incision laterally along a line connecting the ante-
rior superior iliac spine with the pelvis symphysis. The
more proximal femoral nerve is exposed by opening the
muscular abdominal wall into the retroperitoneal
space.
Care should be taken to identify and protect the ilioinguinal
nerve.
The saphenous nerve can be exposed at the knee by an
incision made parallel and lateral to the tendon of the sarto-
rius muscle. The main trunk of the saphenous nerve may be
hidden behind the saphenous vein because these two struc-
tures maintain an intimate relationship down the leg. The
infrapatellar branch travels from lateral to medial just be-
low the level of the tibial plateau.

956
Peripheral Nerve: Lumbosacral Plexus
Iliacus muscle
Sympathetic
chain
Subcostal
nerve
lateral femoral
cutaneous
nerve
Femoral branch
Gential branch
B
genitofemoral nerve
genitofemoral nerve
Figure
131-3
(A) The lumbar and sacral plexus. (B) Retroperitoneal
exposure of the upper lumbar plexus.
Psoas
major
muscle
.
Sympatheticchain
,
Iliohypogastric
nerve
Ilioinguinal nerve
/
Lateral femoral
--
----
-
cutaneous
nerve
Femoral nerve
II
II
'/
mL.L
a,\\ \ \
\\
\\\
\
Femoral nerve
\ (
If
IIJIf ¥
r""\)lw\\
]
Iliacus muscle
.JI
,.
an fl
.
,
"''''"II
...--.r'U..
to
\
..
'H
,
Obturator
nerve
Femoral
branch
-
h :11
ftT
T'
II
'-
,,\...018.,,....
\ t
- -
Gluteal
nerve
genitofemoral
nerve
1\1
"''''
IiI! JIll"
., -
.. ,..
'\1/ ;',
if..\
Sciatic nerve
Pudendal
nerve
./
1">-..
\
'f
/
.IF/
Gential branch
A
genitofemoral
nerve

.
The Obturator
Nerve
131
Approachto Nervesof the Lower Extremity
957
Theobturatornervetakes its originfromthe ventraldivi-
sionof the ventral rami of L2,3, 4. The nerve forms in the
psoasmajor muscle but unlike the femoral nerve it passes
behindthe common femoral vessels lateral to the internal
iliacartery. The nerve travels through the lesser pelvis to
the obturator foramen. It exits the obturator foramen
passingover the obturator internus muscle. As it passes
through the obturator foramen into the anterior thigh the
nerve divides into an anterior and a posterior branch6
(Fig.131-1).
The anterior
branch travels anterior to the adductor
brevis and behind the pectineus
and adductor
longus
muscles.Abranch joins the medial cutaneous nerve pro-
viding sensation to the medial upper thigh. This area of
sensory innervation can, on occasion, extend down to the
knee.Motor branches pass to the adductor longus, adduc-
tor brevis, and gracilis muscles. The nerve ends at the
femoralartery.
The posterior branch passes behind the adductor brevis
andin front of the adductor magnus. This nerve enters the
popliteal fossa along with the femoral artery to innervate
thekneejoint.
Fortunately surgeons are rarely asked to repair the nerve
withinthe pelvis where its deep location makes repair quite
difficult.
Exposure of the Obturator
Nerve in the Thigh
Extra pelvic exposure of the obturator nerve is accom-
plishedthrough a linear incision, which begins over the pu-
bictubercle and extends down the medial leg. The interval
between the pectineal and the adductor longus, both of
which originate from the pectineal line of the pubis, is de-
veloped.Ifdifficulty is found opening this plane the medial
intervalbetween the adductor longus and adductor magnus
can be opened and the adductor longus can be mobilized.
Theproximal pectineus may need to be detached to afford a
good look at the nerve. The anterior division of the obtura-
tor nerve will be seen passing over the obturator brevis
muscle.Exposure of the posterior division may require par-
tial sectioning of the obturator brevis muscle. The posterior
branch will be seen behind this muscle.
.
The SciaticNerve
The sciatic nerve is composed of contributors from L4-S3.
Thetwo lumbar nerves L4and LScombine to form the lum-
bosacral branch, which crosses the ala of the sacrum tojoin
the upper three sacral roots forming the sciatic nerve. From
its inception the sciatic nerve contains the tibial division,
which is formed by the ventral division of L4-S3, and the
peroneal division, which is formed by the dorsal division of
L4-S3.Thesciatic nerve exits through the greater sciatic
notch below the piriformis muscle and above the superior
gemellus under the cover of the gluteus maximus muscle.
The fibers destined to form the peroneal nerve segregate
lateral to the fibers destined to form the tibial nerve.
The sciatic nerve travels down the thigh posterior to the
exterior rotators of the hip (the obturator internus, the
gemellus, and the quadratus femoris) and the adductor
magnus. The nerve is flanked medially by the semitendi-
nous muscle and laterally by the short head of the biceps
femoralis and is crossed posteriorly by the long head of the
biceps femoralis muscle because that muscle makes its way
from the ischial tuberosity to the head of the fibula. Soon
after exiting from the sciatic notch the sciatic nerve pro-
vides innervation to the hamstring muscles with branches
to the semimembranous, semitendinous, long head of the
biceps and adductor magnus originating from the tibial di-
vision and branches to the short head of the biceps originat-
ing from the peroneal division.
Most commonly the sciatic nerve divides into a medial
tibial division and a smaller lateral peroneal division in the
lower third ofthe thigh proximal to the popliteal fossa.7The
tibial nerve passes behind the knee joint covered only
by adipose tissue, fascia, and skin. As the nerve enters
the popliteal fossa it lies lateral to the artery but in the
midfossa it passes behind the artery to continue distally on
the artery's medial side. The nerve leaves the popliteal fossa
passing between the heads of the gastrocnemius muscle
and continues distally sandwiched anterior to the soleus
muscle and behind the posterior tibialis muscle emerging
4 cm above the ankle from the medial side of the tendon
calcaneus.
Muscular branches to the gastrocnemius
and soleus
muscles originate at approximately the level of the medial
epicondyle of the femur, and 3 to 5 cm proximal to the
knee joint the tibial nerve contributes to the sural nerve.
This cutaneous
branch passes between the head of the
gastrocnemius muscle before perforating the deep fascia
and communicating with the sural communicating branch
of the peroneal nerve. The combined sural nerve then
travels along the lateral border of the Achilles tendon,
passing between that tendon and its lateral malleolus.
Motor branches from the tibial nerve are given to the pos-
terior tibialis, flexor, hallucis longus, and flexor digitorum
longus muscles and the nerve travels behind the soleus
muscle.
The tibial nerve emerges from the medial side of the ten-
don calcaneous to pass between that tendon and the lateral
malleolus under the flexor reticulum.s In most cases the
nerve divides into the medial and lateral plantar nerves
within 1 cm of the medial malleolus. The calcaneal branch
to the heel can originate from the posterior tibial nerve, the
lateral plantar nerve, and, rarely, from the medial plantar
nerve.9The calcaneal branch can be duplicated. Beneath the
flexor retinaculum the tibial nerve lies posterior to the pos-
terior tibial artery. Two veins accompany the artery and
nerve through the tarsal tunnel.
The medial and lateral plantar nerves enter the foot
within adjacent but separate canals. The roof of the canal
for the lateral plantar nerve is the aponeurosis of the foot,
and the roof for the canal of the medial plantar nerve pro-
vides the origin of the abductor hallucis brevis.

958
PeripheralNerve:LumbosacralPlexus
.
Exploration of the Intrapelvic
SciaticNerve
Because of the slope of the sacrum away from the surgeon,
exploration of the sacral plexus is difficult through the
retroperitoneal approach. Atransperitoneal exposure affords
a good exposure of the proximal sciatic nerve and control of
the adjacent vasculature. The peritoneal cavity is opened
through a midline or transverse approach, and the peri-
toneal contents are displaced superiorly with moist sponges
exposing the posterior peritoneum. The posterior peri-
toneum is opened exposing the lower lumbar and sacral
plexus. The descending portion of L4joins the L5root ante-
rior to the promontory of the sacrum. The three upper sacral
roots join this trunk, separated from the sacrum by the ori-
gin of the piriformis muscle. Branches of the internal iliac
artery and the superior gluteal, inferior gluteal, and internal
pudendal arteries pass through the proximal sacral plexus.
. Exposureof the Proximal
Extrapelvic SciaticNerve
Alimited view of the sciatic nerve can be accomplished by
a muscle-splitting approach through the gluteus maximus
muscle (Fig. 131-4). This approach is similar to the poste-
rior approach in the hip. The patient is placed in the three-
quarter prone position with the affected side up. An 8 to
10 cm incision begins at the greater trochanter and ex-
tends medially in line with the fibers of the gluteus max-
imus. The fascia over the gluteus maximus is cut in line
with a skin incision and the muscle fibers of the gluteus
maximus are split revealing the short external rotators of
the hip. Further exposure can be obtained by extending
the fascial incision into the fascia lata. The nerve is found
encased in fat lying upon the short external rotators of
the hip (the obturate extensor, the two gemelIi, and the
quadratus femoris). Asufficient length of piriformis mus-
cle is exposed so that that muscle can be cut through this
exposure.
Amore extensive approach described by Henry lifts the
gluteus maximus muscle to expose the entire proximal
portion of the sciatic nerve.12Aquestion mark-shaped inci-
sion is made in the skin passing 3 cm inferior and parallel
to the iliac crest, down to the greater trochanter parallel
with the femur to the inferior edge of the gluteus maximus
muscle, medial just inferior to the gluteal fold to the mid-
line of the thigh, and then inferiorly along the midline of
the thigh. The posterior femoral cutaneous nerve, which
travels down the posterior midthigh, must be avoided. The
gluteus muscle is detached from its insertion into the fe-
mur and the iliotibial track, the interval between the glu-
teus medius and gluteus maximus is developed, and the
gluteus maximus muscle is lifted, hinged on its medial ori-
gin, into the posterior gluteal line of the ileum and the dor-
sal sacrum. The sciatic, superior gluteal, inferior gluteal,
posterior femoral cutaneous, and pudendal nerves can be
seen. The sciatic and posterior femoral cutaneous nerves
are seen exiting the pelvis under the piriformis muscleand
then traveling
caudally over the short external rotators of
the hip.
In the thigh
the sciatic
nerve runs between
the semi-
tendinous
muscle medially and the biceps femoris laterally.
Exposure
can be obtained
by a longitudinal
incision inthe
center of the posterior thigh. Care should be taken not toin-
jure the posterior
femoral cutaneous
nerve that runs over
the long head of the biceps femoris beneath the deepfascia.
Once the deep fascia is opened only the long head ofthebi-
ceps, which crosses the nerve from medial to lateral, stands
between the surgeon and the sciatic nerve. In the distal
thigh the skin incision curves laterally along the medial
border of the tendon of the biceps femoralis. Ifexposurebe-
low the knee joint is needed the skin incision returns tothe
midline
along the posterior
cutaneous
crease of the knee
joint and then down the midcalf. Care should be taken not
to injure the sural communicating
nerve or the lateral cuta-
neous nerve of the calf, both of which branch from the com-
mon
peroneal
nerve
as it travels
parallel
to the biceps
femoris
tendon
or the sural nerve, which exits from the
tibial
nerve
between
the
heads
of the
gastrocnemius
muscle.
.
Exposureof the Tibial Nerve in the leg
The proximal tibial nerve is exposed between the headsof
the gastrocnemius
muscle (Fig. 131-5). The midpointofthe
gastrocnemius is marked by the short saphenous veinex-
ternal
to the deep fascia and the sural nerve deep to the
deep fascia. Once the deep fascia is opened the musclebel-
lies of the gastrocnemius can be separated with fingerdis-
section. The tibial nerve can be followed distalIy to whereit
dives behind the soleus arch.
Distally the tibial nerve emerges from the medialedge
of the Achilles tendon where the gastrocnemius and soleus
merge to form that tendon -4 cm proximal to the medial
malleolus. The tibial nerve can be isolated behind thepos-
terior tibial artery after it emerges from under the Achilles
tendon through a vertical incision placed halfwaybetween
the Achilles tendon and the medial malleolus (Fig.131-6).
Toexpose the nerve behind the soleus muscle, the soleus
bridge must be cut from proximal to distal and the fibers
of the soleus muscle divided or, if more extensiveexposure
is required, the soleus muscle can be detached fromthe
tibia12(Fig. 131-7). The detachment of the soleus muscle
from the middle third of the tibia is performed fromdistal
to proximal.
The distal neurovascular
bundle is identified
and followed behind the Achilles tendon. Usingthe index
finger to protect this bundle. the attachment of the soleus
muscle is first detached
from the medial edge of the tibia.
Two thirds
of the way up the tibia the attachment be-
comes thicker and more fibrous and passes obliquelyto
the lateral
(inner)
edge of the tibia. Having freed the tibia
attachment the soleus muscle can be rotated laterallyex-
posing the tibial nerve. This is analogous to the exposure
of the median nerve behind the flexor digitorum sublimis
muscle.

Gluteus medius
muscle
"...----
Line of incision
Posterior cutaneous
A
nerve
Gluteus medius
muscle
Gluteus maximus
muscle
III,
--j
B
Posterior cutaneous
nerve
Greater
trochanter
Line of incision
Greater
trochanter
Figure 131-4
(A) The sciatic nerve and posterior
cutaneous nerve of the thigh are covered bythe gluteus
maximus.Alimited view of the sciatic nerve can be ob-
tained bysplittingthe fibersofthe gluteus maximus.(8) A
more extensive exposure requires detaching the gluteus
maximus from the iliaccrest and cutting the insertion
ofthe muscleinto the femurand the iliotibialtrack.
959

960
Peripheral Nerve: Lumbosacral Plexus
Gluteus medius
muscle
Posterior
cutaneous
nerve
c
Divided gluteus
maximus muscle
Gemellus superior
muscle
Obturator
internus
muscle
Gemellus inferior
muscle
Iliotibial
tract
Quadratus
femoris
muscle
Adductor
magnus
muscle
Sciatic
nerve
Figure 131-4 (Continued)
(C) The sciatic nerve emerges
under the piriformis muscle and over the short externalrota.
tors of the hip.

r
131
Approach to Nerves of the LowerExtremity
961
Soleus muscle
.
Commonperoneal
nerve
Popliteal vein
andartery
Tibialnerve
Gastrocnemius
muscle
Suralnerve
Shortsaphenous
vein
Figure 131-5
In the upper leg, the posterior tibial nerve
can be exposed down to the soleus bridge between the
headsofthe gastrocnemius muscle. The interval between
the heads is marked superficially by the short saphenous
vein and below the deep fascia by the contribution from
the posterior tibial nerveto the sural nerve.
Calcaneal nerve
Flexor retinaculum
Abductor hallucis muscle
Medial and lateral plantar nerves
Figure
131-6
The posterior
tibial
nerve isfreed in the tarsal tunnel where
it runs posterior to the posterior tibial
artery. The lateral and medial plantar
nervesarefollowed into their respective
canals.Careistaken to identify and pre-
servethe calcanealbranch.

Lineof
Incision
dividing
medial pier
of soleus arch
Posterior
tibialartery
Flexor digitorum
longus muscle
Deep fascia
A
Posterior
tibial
artery
B
\
Popliteal artery
Gastrocnemius
muscle
Divided tibial
attachment of
soleus muscle
Posterior tibial
nerve
Figure 131-7
(A)Toexpose the posterior tibial nervebe-
hind the soleus muscle. the nerve is first isolated abovethe
medial malleolus. (8) The soleus insertion into the tibiaisdi-
vided from distal to proximal protecting
the neurovascular
bundle with the index finger.

. Exposure of the Tibial Nerve in the Ankle
131
Approachto Nervesofthe LowerExtremity
963
Theposterior tibial nerve is best located under an exci-
sionthat begins 3 to 4 em proximal to the medial malIeolus
andtravels distalIy along a course halfway between the me-
dialmalIeolus and the tendon calcaneus (Fig. 131-6). Care
mustbe taken to avoid the terminus of the saphenous nerve.
Theincisioncurvesforwardto terminate at the edge of
theplantar aspect of the foot. The origin of the adductor
hallucismuscle may be seen. The deep fascia is opened and
the nerve is identified behind the anterior tibial artery
proximalto the flexor retinaculum. The flexor retinaculum
isreleased from proximal to distal. Care is taken to preserve
thecalcaneusbranchofthe tibial nerve.Theplantarnerves
arefolIowed into their respective tunnels, which requires
cuttingthe fascia underlying the adductor halIucis.
.
Peroneal Nerve
Theperoneal
nerve travels over the lateral head of the gas-
trocnemius,
under
cover of the thick popliteal
fascia and
medial edge of the biceps tendon. It passes around the neck
ofthe fibula and, prior to diving between
the two heads of
theperoneus longus muscle, the common peroneal nerve
givesoff a lateral cutaneous nerve, which innervates the up-
perposterior leg and a communicating branch to the sural
nerve.10Two articular branches to the knee joint originate
atthe peroneus longus bridge.
Theperonealnervebifurcatesunderthe coverofthe per-
oneuslongus muscle into the superficial and deep peroneal
nerves.The superficial peroneal nerve passes between the
peroneus longus and the extensor digitorum longus inner-
vatingthe peroneus longus and brevis. Two-thirds of the
waydown the leg, the nerve emerges from between those
two muscles to pierce the deep fascia and bifurcate into
themedialdorsaland intermediatedorsalcutaneousnerves
of the leg, which supply skin sensation to the dorsum of the
ankle, foot, and toes.l1
The deep peroneal nerve passes under the tendinous ori-
gin of the extensor digitorum longus and travels distalIy on
the anterior interosseous membrane between the extensor
digitorum longus muscle and the anterior tibialis muscle.
The deep peroneal nerve innervates the extensor digitorum
longus and the anterior tibialis through short branches,
which tether the nerve proximally. More distally it inner-
vates the extensor hallucis longus and peroneus tertius
muscles. The anterior tibial artery accompanies the nerve
in the distal two thirds of the leg. The deep peroneal nerve
emerges lateral to the tendon of the extensor hallucis
longus and medial to the tendon of the extensor digitorum
longus and passes under the extensor retinaculum of the
ankle lateral
to the anterior
tibial artery. The nerve
branches with its lateral branch innervating the extensor
digitorum brevis and its medial branch passing under the
tendon of the extensor halIucis brevis to innervate the first
dorsal web space.
.
Exposureof the Common Peroneal
Nerve at the Knee
Theperoneal nerve can be exposed as it passes around the
head of the fibula by an extension of the sciatic nerve
exposure or by an S-shaped incision that begins medial to
the tendon of the biceps femoris muscle, curves over the in-
ferior aspect of the fibular head, and passes over the inter-
val between the peroneus longus and the extensor digito-
rum 10ngus13(Fig.131-8). The common peroneal nerve can
be palpated as it passes aroundthe head of the fibula.The
deep fascia over the nerve is divided taking care not to in-
jure the sural communicating and lateral cutaneous nerves
as they piercethe fascia.Thefibrousedgesof the peroneus
longus and the extensor digitorum longus are cut exposing
the bifurcation of the nerve.

964
Peripheral Nerve: Lumbosacral Plexus
Superior extensor
retinaculum
Extensor digitorum
longus muscle
Inferior
extensor
retinaculum
Extensor hallucis
brevis muscle
.
Exposureof the Superficial
Peroneal Nerve
Extensor hallucis
longus
Deep peroneal
nerve
Dorsalis
pedis
artery
The superficial peroneal nerve passes anterior to the per-
oneus brevis and pierces the deep fascia of the leg 10 to
12 cm above the ankle. Toexpose this potential site of en-
trapment a linear incision is made lateral to the extensor
digitorum longus from 7 to 12 cm proximal to the ankle.
One of the two branches of the superficial peroneal nerve,
the medial dorsal cutaneous nerve or the intermediate dor-
sal cutaneous nerve, can be identified superficial to the
deep fascia and followed proximally to where the superfi-
cial peroneal nerve pierces the fascia and passes behind the
peroneal brevis muscle.10
Figure 131-8
Thedeep peronealnervepassesundertheextensor
retinaculum of the foot between the tendons of the extensorhalli.
cus longus and the extensor digitorum longus. The nervecontinues
underthe tendon ofthe extensorhallicusbrevisto innervatethefirst
dorsal web space.
.
Exposure of the Deep Peroneal
Nerve at the Ankle
Thedeep peroneal
nerve travels down the leg between the
extensor
hallucis
longus and the anterior
tibialis muscles
(Fig. 131-9).
An inch above the ankle the nerve emerges
lateral to the tendon of the extensor hallucis longus andme-
dial to the tendons
of the extensor
digitorum
brevis.The
nerve can become entrapped
under the extensor retinaculum
at the ankle or under the tendon of the extensor hallucisbre-
ViS.8.14The nerve can be identified
by palpating the pulseof
the anterior tibial artery or the movement ofthe extensorhal-
lucis longus tendon. The lateral portion of the nerve.which
innervates
the extensor
digitorum
brevis, can be biopsiedto
provide motor fascicles. The extensor retinaculum can becut
to relieveentrapment of the distal deep peronealnerve.

r
131
Approachto Nervesof the LowerExtremity
965
\
Commonperoneal
nerve
Lateral
sural
cutaneous
nerve
Superficial peroneal
nerve
Deep peroneal
nerve
Gastrocnemius
muscle
Peroneus longus
muscle
J
i
\
f
Soleus
muscle
Ext.digitorum
longus muscle
Tibialis anterior
muscle
References
1. Kim DH, Kline DG. Surgical outcome for intra-
and extra pelvic
femoral nerve lesions.j
Neurosurg
1995;83:783-790
2. KlineDG,KimD.Midha R,Harsh C,TielR.Management and results of
sciatic nerve injuries:
a 24-year experience. J Neurosurg 1998;89: 13-23
3. Kline DG, Kim D, Midha R. Hudson AR.Lowerextremity nerves. In:
Nerve Injuries: Operative Results for Major Nerve Injuries, Entrapments.
and Tumors. Philadelphia:
WB Saunders; 1995:289-344
4.
Edelson jG, Nathan
H. Megagia
paresthetica.
Clin Orthop
1977; 122:
255-262
5. Sunderland
S.Femoral nerve. In: Nerves and Nerve Injury. Edinburgh:
Churchill Livingstone;
1978:999-1006
6.
Sunderland
S. Obturator
nerve.
In: Nerves and Nerve Injuries.
Edin-
burgh: Churchill Livingstone;
1978:992-998
7. Sunderland
S. Rabh. The intraneural
topography
of the sciatic nerve
and its popliteal
divisions
in man. Brain 1948;71 :242
,
Figure 131-9
The common
peroneal nerve gives rise to the
lateral cutaneous
nerve of the calf and the sural communicat-
ing nerve prior to passing around the fibula. After parting from
the superficial peroneal nerve. the deep peroneal nerve passes
under the fibrous origins of the peroneus
longus and extensor
digitorum longus muscles.
8.
Marinacci AA. Neurological syndromes of the tarsal tunnels. Bull Los
Angeles Neurol Soc 1968;33:90-100
9.
Dellon AL, MacKinnon SE.Tibial nerve branching in the tarsal tunnel.
Arch Neuro11984;41 :645-646
10.
MacKinnon SE.Dellon AG.Other lower extremity nerve entrapments. In:
Surgery of the Peripheral Nerve.New York: Thieme; 1988:319-346
11.
Kopell HP.Thompson WAL Superficial peroneal nerve. In: Peripheral
Entrapment Neuropathy. Baltimore: Williams &Wilkins; 1963: 39-42
12.
Henry AK. Extensile Exposure. 2nd ed. Edinburgh:
Churchill
living-
stone; 1973
13.
Mont MA, Dellon AL. Chen F.Hungerford
MW, Krackow KA. Hunger-
ford DS.The operative treatment of peroneal nerve palsy. JBonejoint
Surg Am 1996;78:863-869
14.
Dellon AL Deep peroneal nerve entrapment
on the dorsum of the
foot. Foot Ankle 1990;11:73-80

132
SuralNerve
Rajiv Midha
. Anatomy
.
Sural Nerve Biopsy
Closure
.
Sural Nerve Harvesting
.
Sural Nerve Injury
Etiology
Diagnosis
Management
.
Case #1 :Sural Nerve Neuroma
.
Case # 2: Sural Nerve Entrapment
.
Conclusion: Sural Nerve Injuries
The sural nerve is clinically important for several reasons. It
is the single most commonly biopsied nerve for diagnostic
considerations of a peripheral neuropathy.I,2 It is also the
nerve most frequently harvested for use in nerve autograft-
ing.3 Finally, sural nerve injuries,
although
relatively
uncommon, often result in a painful or irritable nerve con-
dition or produce a painful neuroma that can be challenging
to manage.4This chapter reviews the pertinent anatomy of
the sural nerve as well as the appropriate techniques for
biopsy and harvesting of the nerve. The management con-
siderations in the treatment of sural nerve injuries are also
discussed,and illustrated by two representative cases.
. Anatomy
The sural nerve carries primarily 51 sensory fibers, receiv-
ing branches from the posterior tibial (medial sural) and the
peroneal (lateral sural) nerves in the popliteal fossa.sThere
is one contribution from each in -80% of cases.6ln the re-
mainder, the sural nerve arises exclusively from the poste-
rior tibial6 but occasionally from the peroneal alone.7 The
sural branch from the tibial lies between the two heads of
the gastrocnemius muscle, deep to the fascia.sHowever,the
lateral sural (also called the peroneal communicating
branch) is superficial to the gastrocnemius fascia and at
times may arise in common with another cutaneous branch
966
from the peroneal, the cutaneous peroneal nerve.5,sThe
medial sural nerve descends deep to the gastrocnemius
fascia in the proximal lower leg running in the posterior
midline. It emerges from the fascia into the subcutaneous
plane about halfway down the leg, an average of 16cm
proximal to the lateral malleolus.s Shortly after emergence
from the fascia,there is an anastomosis with the lateral
sural nerve found in 75 to 84%of cadaveric dissections,5.!
From here the combined sural nerve pursues a slightly
oblique course from the initial midline position to lieposte-
rior to the lateral malleolus and anterior to the Achillesten-
don (Fig. 132-1). In this oblique location, the nerveis
closely related to the small saphenous vein, which servesas
an excellent landmark for finding the nerve. Just abovethe
ankle level,the nerve starts to branch.Thestandardzone
of sensory
innervation
(and
sensory
loss following
injury, biopsy, or nerve harvesting) is to the dorsal lateral
foot (Fig.132-1).
On cross section, the main sural nerve has a diameter
ranging from 2 to 4 mm, whereas the lateral andmedial
sural contributors have variable diameters, usually ranging
from1 to 2 mm.6Approximately50%ofthe areaofthesural
nerve is composed of (primarily) epineurial connectivetis-
sue, containing one longitudinal nutrient artery andoneor
more veins.1.6The main sural nerve (just proximal tothe
lateral malleolar level) is multifascicular. On microscopic
evaluation, it contains six to 15 fascicles (rarely up to20),
typically arranged in a diffuse or ungrouped fashion.1.6

\
Lesser samphenous
vein
132
SuralNerve
967
Lateral sural nerve
(Peroneal
communicating
branch)
Medial sural cutaneous
nerve
Sural nerve
Lateral malleolus
. SuralNerve Biopsy
The detailed indications for peripheral nerve biopsy are
beyond the scope of this chapter and are covered well in
standard neuropathy textbooks.2 In general, nerve biopsy is
indicated in only a small subset of patients with peripheral
neuropathy, where a specific diagnostic consideration is
beingentertained.2 These patients should have already un-
dergone a detailed evaluation and an exhaustive noninva-
siveworkup from a qualified neurologist. In practice, the
neurologist,who requires a nerve biopsy to complete or ar-
riveat a specific diagnostic conclusion, usually refers the
patient.
The sural nerve is the most frequent nerve to undergo
biopsy for several reasons.2 It has a reliable anatomical
course, which makes it easily accessible for prebiopsy
Figure 132-1
The sural nerve, with the contribu-
tions from tibial (medial sural) and peroneal (lateral
sural or peroneal communicating
branch) nerve,
along with the relationships of the nerveto the lesser
saphenousveinand lateral malleolus.Thetypical sen-
sory zone of sural nerve innervation is illustrated
(stippling).
electrophysiological studies and also removal at surgery. It
is a cutaneous nerve, whose resection is usually well toler-
ated, with low morbidity. The disease process frequently in-
volves the nerve in question and it is situated where trauma
or injury from day-to-day activities is unlikely. Finally,the
sural nerve has an appropriate anatomical makeup, includ-
ing presence of vessels and connective tissue, reasonable
caliber, fascicular number, and lack of intertwining fascicles
over a 6 to 10 em distance (so that individual fascicles can
be dissected out for tease preparation) to facilitate neu-
ropathological interpretation.
Sural nerve biopsy is performed as an outpatient proce-
dure, using local anesthetic only, in the majority of cases.
The sural nerve is most easily biopsied with the patient in a
lateral position, with the side being biopsied facingupward.
Placing a pillow or padding between the dependent knee

968
Peripheral Nerve: Lumbosacral Plexus
Figure 132-2
The incisionfor sural nerve biopsy is in the trough
between the lateralmalleolus(LM)and Achillestendon.
and the upper one aids patient comfort. The lateral lower
leg and ankle region is suitably prepped and draped, follow-
ing which 1%lidocaine with 1:200,000 epinephrine is infil-
trated subcutaneously in the trough between the lateral
malleolus and Achilles tendon. Starting 1 cm behind and
just above the lateral malleolus, the incision is extended 10
cm cephalad in a linear and slightly posterior oblique direc-
tion (Fig. 132-2). The lesser saphenous vein is first identi-
fied in the deep subcutaneous
plane, lying immediately
deep to the semitransparent
Scarpa's fascia (Fig. 132-3A).
With division of the fascia directly over the vein and its
retraction, the sural nerve is usually exposed just deep(or
medial) to the saphenous vein (Fig.132-38). Asmallbranch
or two from the vein adjacent to the lateral malleolusmay
need to be coagulated and incised to facilitate nerveexpo-
sure and procurement. Approximately 10cm length ofsural
nerve is dissected out, using sharp techniques, fromthe sur-
rounding tissue. The patient is then warned that the nerve
will be cut because this will result in severe but transient
pain. For this reason, the proximal end of the sural nerve
segment being harvested is first cut. Using gentle traction,
the nerve is sharply and quickly divided. The stump ofthe
sural nerve remaining in the patient is allowed to retract
into deep subcutaneous tissue proximal to the apexofthe
wound, minimizing the risk of painful neuroma formation.
Then the final removal of the nerve proceeds with anyfur-
ther distal dissection and cutting of the nerve. It is impor-
tant to not coagulate directly on the nerve, handle it gently
at all times, and only grasp the nerve with forceps at itscut
end to avoid crush and injury artifact. The fresh nervespeci-
men is directly handed to the pathology technologist.
Closure
The wound is closed in layers using 2-0 polyglcolicacid
(PGA) absorbable
suture
on a cutting
needle
in a running
fashion for the subcutaneous tissue, and a 3-0 PGAsubcu-
ticular
suture
for skin closure.
A strip dressing
is applied
to the incision, bolstered
by 4 x 4 gauze and Kling wrapped
in a circumferential fashion around the lower leg and ankle
to apply gentle
pressure.
The patient
is asked to ambulate
immediately
but to elevate
the leg at night and when sit-
ting. The dressing
is removed
after 5 days and the incision
left exposed to air thereafter.
On occasion, the neurosurgeon will be asked to perform
both a muscle and a nerve biopsy. Harvesting the sural
nerve
in midcalf
allows
for simultaneous
gastrocnemius
muscle biopsy. The drawback
is that the sural nerve hereis
often smaller in diameter, and consists of four to eight fasci-
cles because
it is devoid
of the
contribution
from the
peroneal. This information should be conveyed to the neu-
ropathologist.
On the plus side, sensory
loss may be lessor
AI1IJI1J!i
";
-
1Tff.~--
B
Figure 132-3
(A) The lesser saphenous vein serves as an excellent anatomical landmark for the sural nerve, which lies just deep to it and slight~
posterior
(B) in the case shown
here.

..
132
Sural Nerve
969
noneand the chance of a painful neuroma lessened because
theproximal sural nerve stump is deep to te fascia, within
anintermuscular plane. With the patient prone, a 10 cm
longitudinalincision is made in the posterior calf midline.
Thesural nerve is immediately deep to the fascia covering
thegastrocnemius muscle here. After incising the fascia,the
lessersaphenous vein and nerve should be sought. At times
thenerve may be slightly deeper, within the intermuscular
tissue,between the two heads of the muscle. Afterharvest-
ingthe nerve, a generous sample of gastrocnemius muscle
maybe removed from the superior part of the exposure
wherethe muscle is fleshier and less tendinous. Both fresh
samplesare given to the neuropathology personnel for ap-
propriate handling. The fascia, subcutaneous tissue, and
skinare then closed in layers and a pressure dressing ap-
plied,as already described.
. SuralNerve Harvesting
Thesural nerve is the most commonly used donor nerve for
grafting for several
reasons.3 The dissection
is fairly
straightforward. Morbidity of harvesting the sural nerve is
relativelylow.An ample amount of donor nerve isavailable,
which facilitates grafting in major nerve reconstructive
cases.From its origin in the popliteal fossa, as a branch of
the tibial nerve, to the level of the ankle where it starts to
divideinto many small branches, -30 to 50 cm of nerve can
be obtained from each adult leg (Fig. 132-4). Because the
lateral sural nerve in -20% of cases provides the major or
solecontribution,s.7.sdissection of the peroneal communi-
catingbranch is especially important to obtain the maximal
amountof graft material (Fig.132-4).
Excision of the sural nerve is easiest with the patient
prone because this facilitates exposure. However, the ma-
jority of peripheral nerve reconstructive cases involve the
upperextremity, repaired with the patient in a supine posi-
tion.Special attention to positioning ofthe lower extremi-
tiesis required for the supine patient (Fig. 132-5). Abean-
bag is placed under the iliac crest to flex and internally
rotate the hip. The knee is flexed -40 degrees, and the an-
kle is dorsi-flexed and also internally rotated. The lower
limb is also positioned close to the edge of the operating
roomtable to allow good access to the posterolateral aspect
ofthe lower leg for exposure and removal of the entire sural
nerve.
There are two alternative techniques for the incision to
expose the sural nerve (Figs. 132-4A and 132-6). Alongi-
tudinal incision, extending from just behind the lateral
malleolus to the level of the popliteal fossa, is most
frequently employed (Fig. 132-4A). For mostly cosmetic
reasons, other surgeons prefer a series of small transverse
incisions along the course of the nerve (Fig. 132-6). In
either case, one starts with a longitudinal incision several
centimeters long fashioned approximately a centimeter
posterior and superior to the lateral malleolus and extend-
ing cephalad from there (Fig. 132-6). The sural nerve is
easily identified in the subcutaneous plane, in association
with and often just deep to the small saphenous vein
(Fig. 132-3). The nerve is circumferentially
exposed,
A
B
Figure 132-4
(A) Suralnerve harvestingthrough a longlongitudinal
incision, with procurement
of both lateral and medial components
so
that
(B) the
maximal amount
of sural nerve
has been
obtained
(-45
cm in total).
surrounded with a vasoloop, and raised from the subcuta-
neous tissue. Gentle traction on the nerve and palpation
confirm the course of the nerve and the incision is appro-
priately extended obliquely up the leg toward the posterior
midline of the calf. The surgeon continues to mobilize the
nerve and free it from the subcutaneous tissue. Small ve-
nous branches from the saphenous nerve that cross the
nerve can be coagulated and incised to allow release of the
nerve. At approximately the midcalf level, the nerve dives
deep under fascia overlying the gastrocnemius
muscle.

970
Peripheral Nerve: Lumbosacral Plexus
L
_.1/
At this point, there can be substantial contributions from
the lateral sural (peroneal communicating)
nerve (Fig.
132-4). Ifthis is the case, then this can be dissected out to
obtain adequate graft material, as required. The peroneal
communicating branch remains subcutaneous in its course
toward the main peroneal nerve. On the other hand, the
main sural nerve from midcalf level to the popliteal fossa
remains deep to the fascia, requiring incision of the fascia
up and along the posterior midline of the leg.
The superior extent of the incision to harvest the sural
stops just below the knee crease. One should not cross the
knee crease because this can result in a painful scar. Note
Figure 132-5
Operative positioning of the lower extremity
of the supine patient for sural nerve harvest (inset). Hipis
flexed and internally rotated with a beanbag placed underthe
iliac crest, the knee is flexed -40
degrees, the ankle isdorsi.
flexed and inverted, with 2 in. cloth tape applied atthe fore.
foot to aid positioning.
alsothat the incisionat the anklelevelisdesignedtoavoid
contactwithconventionalfootwearand shouldnotbecome
too troublesomeforthe patient.Additionally,ifoneexcises
the entire sural nerve and leaves the proximal stumpinthe
high calf or popliteal region, then the chance for painful
neuroma formation is also minimized. The sensory deficit
sustained is quite predictable, usually involving the lateral
surfaceofthe foot(Fig.132-1).Overthe courseoftime,this
diminishes to a relatively small patch of skin anteriorand
inferior to the lateral malleolus along the lateral surfaceof
the foot.Themajorityofpatientstoleratethe sensorydeficit
well without complaints.
Figure 132-6
An initial longitudinal incision
to expose the sural nerve is followed by aseries
of transverse cuts in the posterolateral
andpos-
terior
calf, with
the initial
transverse cut out.
lined by surgical pen.

132
SuralNerve
971
. Sural Nerve Injury
Etiology
Suralnerve mononeuropathy is most commonly secondary
totrauma,9 either surgical or accidental. The sural nerve
maybe injured from laceration by glass, knives, or lawn-
mowerblades, or as a result of blunt injury with concomi-
tantankle and calcaneal fractures.1o.nThe occasional patient
is seen following
industrial
accidents, especially from a
high-pressurewater jet type of trauma. Chronic injury may
occurfrom tightly laced high-topped footwear.9 Iatrogenic
circumstances leading to sural nerve injury
include vein
stripping, Baker's cyst surgery, calf muscle biopsy, and
orthopedic procedures
in the popliteal
area or lateral
ankle region.9-n Biopsy or harvesting of the sural nerve
leadingto a painful neuroma formation is reported with a
variable incidence, ranging from rare in one large series of
nervegrafting, toto a 6%6and up to a 16%incidence in some
series.3Finally, the nerve may be entrapped by scar or con-
genitaladhesions,12.13compressed by a Baker's cyst,14or in-
volvedin a ganglion cYSt,12
Diagnosis
Thediagnosis of sural nerve injuries is clinically obvious in
the majority of cases.There is often a history of preceding
injury, surgery, or trauma. The patient invariably presents
with a painful condition
and often reports sensory alter-
ation in the nerve distribution.
The examiner can easily as-
sessthe location of previous injury in relation to the known
anatomical course of the sural nerve. Occasionally, a neu-
romamay be palpable at or adjacent to the site of previous
traumaor surgery (as in Case# 1.following). The nerve may
alsobe hyperirritable
adjacent to the area of injury, and of-
ten proximal and sometimes distal to this as well, with
paresthesias evoked along the distal distribution
of the
nerve evoked by percussing or palpating over the injured
nervesegment.
Nerve conduction studies may be useful in the diagnosis
ofsural nerve injuries. On careful evaluation, the electrodi-
agnostician may find a complete loss of response and dis-
cern prolonged sensory latency or decreased amplitude. It
is important to compare the affected side with the normal
legfor control purposes.9
The response to one or a series of nerve blocks may be
diagnostic in uncertain cases.An intermediate-duration
lo-
cal anesthetic, such as 0.50% bupivacaine (Marcaine) is in-
stilled in the area of the trigger point adjacent to the nerve
in sufficient
volume (5-10
mL) to obtain effective local
anesthetic blockade of the nerve. The patient is then asked
to monitor the degree of pain carefully and report back in 1
week. Elimination or substantial relief of the pain for>
24
hours (which exceeds the duration of local anesthetic ac-
tion) is graded as a positive response. If effective relief can
beconfirmed on a second or possibly third procedure, then
a relatively high degree of confidence is achieved that the
areaof previous nerve injury is in fact the main peripheral
source of the patient's pain condition. In caseswhere un-
certainty still exists or more objective evidence is needed,
one may entertain a blinded placebo block to confirm the
diagnosis.
Management
The majority of these patients have a painful neuropathic
condition. Sensory loss is not clinically
important.
In this
circumstance, the goal is to eliminate
the patient's pain
problem. The initial approach is almost always conservative.
This entails
watchful
waiting
because many
patients
achieve an acceptable pain control over the course of time.
The patient is referred to a physiotherapist
and undergoes
therapy and other physical modalities of treatment. Often,
this alone will control the pain syndrome to an acceptable
level. Many of these patients have already gone to a pain
clinic and been given various medications. If not, a course of
tricyclic
agents
is worthwhile.
I usually
begin
with
amitriptyline
(Elavil) 25 mg at night (10 mg in geriatric
patients) and ask the patients to increase this to 50 mg per
night after 3 weeks, if required. It is stressed to the patient
that a 6- to 8-week trial of tricyclics is needed before they
can be abandoned for not providing significant pain relief.
An alternative to amitriptyline
is the use of newer-genera-
tion
serotonin-selective
inhibitors,
such as sertraline
(Zoloft). Other medications that are occasionally beneficial
include
anticonvulsant
agents such as carbamazepine
(Tegretol), phenytoin (Dilantin), and gabapentin (Neurontin)
as well as newer-generation
nonsteroidal anti-inflamma-
tory drugs, such as ketorolac (Toradol). Narcotic medica-
tions should be avoided and discouraged in these situations.
In many of these patients, the presence of a neuroma
along the sural nerve at or adjacent to the injury site is clin-
ically obvious (see Case#1). In other patients, this is not so
clear cut and a series of nerve blocks (as already discussed)
is extremely helpful in determining
whether a peripheral
trigger source of pain is present, and more importantly
if it
may respond to a surgical peripheral nerve procedure (see
Case#2). Occasionally, a series of nerve blocks will achieve
sufficient pain control on their own to obviate the need for
surgery.
For those patients with an obvious painful neuroma, and
others with a painful nerve injury not responding to conser-
vative treatment, especially where a nerve block has been
successful in ameliorating pain, a peripheral nerve surgical
procedure is warranted. There are three general procedures
available for painful cutaneous nerve injury
conditions:
neurolysis, nerve repair (grafting), and neurectomy. Neurol-
ysis carries the benefit of no loss of sensory function (if, in
fact, this is retained postinjury).
It appears to achieve rea-
sonable results where the nerve is primarily entrapped and
not injured.12 However, the results of neurolysis have been
poor for long-term
pain control of lower extremity
cuta-
neous nerve injuries.10Nerve grafting has some theoretical
merit, in that regenerating axons can be directed away from
the zone of nerve injury and scar.15However, patients have
been reported who then develop a neuroma within the su-
ture line, resulting in an equally intractable
recurrence of
pain. to Also, grafting
requires
harvesting
of a donor nerve
and this has obvious drawbacks. The most reliable proce-
dure remains a neurectomy. The patient must accept the
trade-off:
loss of sensory function
for probable relief of

972
Peripheral Nerve: Lumbosacral Plexus
pain. The sural nerve does not supply sensation to a critical
area so that the sensory deficit is well tolerated.
Mypersonal procedure of choice for painful sural nerve
injury is a neurectomy. The principle is that one is operat-
ing or doing surgery on a painful neuroma. Thus I recom-
mend wide excision of the damaged nerve. The proximal
stump is placed well away from the zone of injury. prefer-
ablydeep within healthysubcutaneoustissue or muscle.IS
The proximal stump is also coagulated.lo and depending
on circumstances. I consider burying it within muscle or
even 'adjacent to bone.IS However,there is no absolute
guarantee against reformation of a painful neuroma. The
regenerative capacity of a peripheral nerve is quite great
and. despite all means. the axons from the proximal nerve
stump may regenerate. A variable percentage of patients
may require a second or even a third operation on the
painful neuroma.
Finally. there are a minority of patients with a painful
sural nerve injury whose main pain generator is not in the
periphery but is more central. These patients essentially
have a deafferentation
pain syndrome. As a rule, these
patients will not benefit from a peripheral procedure and
require a central procedure
such as dorsal column stimula-
tor for effective pain control.
.
Case #1 : Sural Nerve Neuroma
A 45-year-old male with human immunodeficiencyvirus
(HIV)-associated
painful peripheral
neuropathy had previ-
ously undergone
sural nerve biopsy. He had a zone ofsen-
sory loss. corresponding
to the usual distribution of the
sural nerve. A year post-biopsy.
he developed onset ofse-
vere sharp and stabbing
pain along the scar. with a trigger
point and palpable subcutaneous
mass proximal to the inci-
sion (Fig. 132-7A). The pain was intractable to medications,
including tricyclic agents that were partially effectiveforhis
generalized
painful peripheral
neuropathy.
At surgery.an
end stump neuroma
was observed
(Fig. 132-78). Theneu-
roma and a generous length of sural nerve proximaltoit
were
removed
(Fig. 132-7C).
The remaining
sural nerve
stump was coagulated
and buried deep to fascia proximalto
the incision. The patient
had immediate
pain relief. which
has been maintained
over a follow-up of 9 months to date,
A-C
Figure 132-7
Operative photomicrographs
from Case #1. (A) The instrument
points to the trigger point and palpable subcutaneous mass2cm
proximal to the prior sural nerve biopsy incision. (8) Deep to this. in subcutaneous
tissue. an end stump neuroma was discovered and (e) resected,
alongwitha considerablelengthofproximalsuralnerve.

. Case # 2: Sural Nerve Entrapment
132
Sural Nerve
973
A54-year-old female developed spontaneous onset of poste-
riorright knee pain 8 years prior to assessment at peripheral
nerve clinic. The pain was sharp, severe, and radiated from
just above the knee crease to the midcalf level in the poste-
rior midline. There was no numbness or paresthesias. Knee
x-rays,investigation for Baker'scyst, and three separate knee
arthroscopies were negative and unhelpful.Physicaland neu-
rologicalexams were normal. other than an area of tender-
nessand trigger point just above the knee crease,where per-
cussion resulted in radiating pain without paresthesia into
the midcalf. A right sural nerve conduction study demon-
strated slightly prolonged latency and decreased amplitude,
but this was comparable to the left sural nerve (uninvolved
leg).Overa month, she underwent three separate blocksinto
the trigger point, using Marcaine. Each produced complete
resolution of pain over 24 hours and -50% decrease of
pain over an intermediate (weeks) duration. This degree of
pain relief persisted for 6 months after the last block, then
pain gradually worsened. When seen 9 and 12 months after
the last block, she felt that her right leg pain was-70%of the
preblocklevel.Atrial of amitryptyline over 2 further months
was unsuccessful. and the patient was relyingon Tylenol#3
for pain control. She opted for surgical exploration of the
sural nerve, which was performed 15 months after the initial
patient evaluation. The procedure was performed using local
anesthesia, with a transverse incision along the knee crease
(Fig.132-8). After incising fascia, the lesser saphenous vein
was identified. Adjacent to this, a small medial sural nerve
was found compressed by a tight band of fascialtissue, which
was exactly deep to her trigger point. Palpation ofthe nerve
and pressure on the band reproduced the patient's pain.The
band was released, and the nerve was excised over a gener-
ous length. Pathology revealed nerve fasciclessplayed by fi-
brous scar.The patient has discontinued Tylenol#3 and has
had>
75%decrease of her pain syndrome over 3 months.
Herneurological exam including sensation in sural nerve dis-
tribution remains normal.
References
1.
Midroni G, Bilbao JM. Normal anatomy
of peripheral
(sural) nerve. In:
Biopsy
Diagnosis
of Peripheral
Neuropathy.
Boston:
Butterworth-
Heinemann:
1995:13-33
2.
Dyck PJ, Giannini
C, Lais A. Pathologic
alterations
of nerves. In: Dyck
PJ, Thomas
PK. eds.
Peripheral
Neuropathy.
Philadelphia:
WB
Saunders;
1993:514-595
3.
Nunley JA. Donor nerves for grafting.
In: Gelberman
RH.ed. Operative
Nerve
Repair
and
Reconstruction.
Philadelphia:
JB Lippincott;
1991 :545-552
4.
Midha
R. Management
of femoral,
saphenous,
and sural nerve
in-
juries.
Perspectives
in Neurological
Surgery 1998;9:67-81
5.
Coert JH. Dellon AL. Clinical
implications
of the surgical
anatomy
of
the sural nerve. Plast Reconstr Surg 1994;94:850-855
6.
Ortiguela
ME. Wood
MB. Cahill
DR. Anatomy
of the
sural
nerve
complex.J
Hand Surg Am 1987;12:1119-1123
7.
Phillips
LH, Morgan
RF.Anomolous
origin of the sural nerve in a pa-
tient with tibial-common
peroneal
nerve anastamosis.
Muscle Nerve
1993:16:414-417
Figure 132-8
From Case#2, the transverse incisioninthe posterior
knee crease and site of medial sural nerve entrapment
by a fascial
band (X)are outlined.
. Conclusion: Sural Nerve Injuries
Sural nerve injuries often produce a severe pain syndrome.
usually refractory to conservative management. The diagno-
sis is often clinically obvious with the appropriate history
and may be aided by the presence of a palpable neuroma
and sensory alteration in the nerve distribution. The posi-
tive response to a series of nerve blocks will help ascertain
the diagnosis in uncertain cases. When a peripheral source
of pain can be documented. then wide neurectomy of the
injured sural nerve or neuroma is often successful in con-
trolling the patient's pain problem.
8.
de Moura W, Gilbert A. Surgical anatomy
of the sural nerve. J Reconstr
Microsurg
1984;1 :31-39
9.
Smith BE, Litchy WJ. Sural mononeuropathy:
a clinical
and electro-
physiological
study [abstract].
NeuroI1989;39(SI
):296
10.
Kline DG. Hudson
AR. Nerve Injuries:
Operative
Results from Major
Nerve Injuries,
Entrapments,
and Tumors.
Philadelphia:
WB Saun-
ders: 1995
11.
Myerson M. Quill GE. Late complications
of fractures
of the calcaneus.
J Bone Joint Surg Am 1993:75:331-341
12.
Pringle
RM. Protheroe
K. Mukherjee
SK. Entrapment
neuropathy
of
the sural nerve. J Bone Joint Surg Br 1974;56B:465-468
13.
Colbert
DS, Cunningham
F. Mackey D. Sural nerve entrapment:
case
report.
Ir MedJ 1975:68:544
14.
Nakano
KK. Entrapment
neuropathy
from
Baker's
cyst.
JAMA
1978:239:135
15.
Mackinnon
SE. Dellon AL.Surgery of the Peripheral
Nerve. New York:
Thieme: 1988

133
Intercostal Nerve
Andrew D. Fine
.
Anatomy
.
Function
.
Neurosurgical Considerations
.
Surgical Technique
Incision and Dissection
.
Outcomes
.
Anatomy
As the spinal nerves exit the intervertebral foramina, they
divide into dorsal rami, which innervate the paraspinous
musculature, and ventral rami. The intercostal nerves repre-
sent the anterior rami of the first 11 spinal nerves of the
thorax. These nerves run laterally and around the thoracic
cavity in the costal groove of their respective ribs. The
nerves run in parallel with the intercostal arteries and veins
at each level, with the veins being superior to the arteries
and the arteries lying superior to the nerves. The anterior
ramus of the twelfth spinal nerve projects forth in the ab-
dominal wall as the subcostal nerve.
Each intercostal nerve lies within an intercostal space
formed by the parietal pleura internally and the intercostal
membrane externally. As the nerve moves laterally, it lies
deep first to the subcostal muscles and then to the innen-
nost intercostal muscle. Externally, as the nerve moves
laterally the intercostal membrane becomes the internal in-
tercostal muscle (Fig.133-1). The first six intercostal nerves
run their course as already described. The seventh, eighth,
and ninth intercostal nerves leave the anterior end of the
intercostal space by passing deep to the costal cartilages
and continue forward in the plane superior to the transver-
sus abdominis muscle. The tenth and eleventh intercostal
nerves pass directly into the abdominal wall because their
corresponding ribs are floating.
The intercostal nerves each have several main branches.
Asthe intercostal nerve originates as the anterior ramus of
the spinal nerve, it immediately gives off two branches,
the gray and white rami communicantes. These branches
974
convey unmyelinated
and myelinated fibers, respectively,to
and from the sympathetic ganglion related to theirgivenin-
tercostal space. The gray ramus typically joins the inter-
costal nerve medial to the point at which the whiteramus
leaves it.
As the intercostal nerve continues around in its costal
groove, it gives off a collateral
branch, which continues in
the same plane but runs inferior to the main branch onthe
upper
border
of the
next
lower
rib. A communicating
branch on the intercostal
nerve below may join this branch.
Continuing laterally, the intercostal nerve givesoffalat-
eral cutaneous branch and then an anterior cutaneous
branch. The lateral cutaneous
branch originates at the pos-
terior axillary line and moves superficially becoming subcu-
taneous
near the midaxillary
line. At this point it splitsinto
anterior
and posterior
branches.
The anterior cutaneous
branch
of the intercostal
nerve enters
the subcutaneous
space near the midline
and splits into medial and lateral
branches.
Numerous muscular branches are given off throughout
the course of the intercostal
nerve and the collateral nerve.
In addition,
many sensory
pleural and peritoneal branches
are given off at their respective levels.
Several branches
specific to certain levels are worthyof
note. The first intercostal
nerve is connected to the brachial
plexus by its equivalent of the lateral cutaneous nerve.
Additionally,the first intercostal nerve has no anteriorcuta-
neous branch owing to its short length. The secondinter-
costal nerve is connected
to the medial cutaneous nerveby
its lateral cutaneous
branch, in this case called the intercos-
tobrachial
nerve.1.2

133
IntercosalNerve
975
Figure133-1
Course and branches of midthoracic intercostal nerves.2
. Function
The first six intercostal
nerves supply the intercostal
muscles of each intercostal space as well as the levatores
costarum and serratus posterior muscles. In addition, they
supply sensation to the skin and parietal pleura of each of
their respective intercostal spaces. The second intercostal
nerve also supplies sensation to the axilla and superior me-
dial portion of the arm via the intercostobrachial nerve.
The seventh through eleventh intercostal nerves supply
the anterior muscles of the abdomen including the trans-
versus abdominis, rectus abdominis, internal obliques, and
external obliques. These nerves also supply sensation to the
skin and parietal peritoneum at their respective levels.1.2
.
Neurosurgical Considerations
The intercostal nerves usually come to the attention of neu-
rosurgeons in patients with chronic pain in the distribution
of these nerves or as a resource for reinnervating damaged
peripheral nerves. Chronic pain patients, if appropriately
selected, do well with lesioning procedures, such as dorsal
rhizotomies and dorsal root ganglionectomies
discussed
elsewhere in this volume.3.4Intercostal nerves may also be
used as a substitute for sural nerves in cable grafting in-
jured peripheral nerves. Additionally, intercostal nerves
have been used in several neurotization
procedures for
reinervating the brachial plexus, phrenic nerve, and lum-
bosacral plexus.s-7 Byfar the most widely studied of these
procedures is neurotization of the brachial plexus to restore
elbow fIexion.s
In patients with brachial plexus injuries who are not
good candidates for nerve grafts, such as those with avul-
sion trauma,
nerve transposition
may be considered.
Friedman reports a success rate of -50% in restoring
greater
than
antigravity
elbow
flexion
strength
in
patients
with preoperatively
flaccid upper extremities
secondary
to brachial plexus avulsion injuries. This is
done by transposing intercostal nerves to the musculocu-
taneous nerve thus reinnervating
the biceps brachialis
muscle.9

J
976
Peripheral Nerve: Other Nerves
. SurgicalTechnique
Incision and Dissection
Toperform the intercostal nerve transposition the patient is
first prepped from spine to sternum and jaw to inferior
costal margin on the side of the injury. After prepping, the
patient is rolled back to the prone position. The proximal
\
A
brachial plexus is first explored through a standard supra-
clavicular approach, checking for any intact nerve roots.If
no intact nerve roots are found. then an incision in thedel-
topectoral
groove is made from the clavicle to the pectoralis
major muscle. This plane is deepened
and the pectoralis is
divided near its insertion into the humerus (Fig. 133-2).
Next the pectoralis
minor is divided from the conjoined lig-
ament. At this point the median nerve should be identified
.
....-
B
Figure133-2
Neurotization of biceps brachia lis using intercostal
nerves. (A) An incision is made in the deltopectoral
groove. (8) The deltopectoral
groove is dissected and the pectoralis major is divided just proximal to its insertion
into the humerus.

133
Intercostal Nerve
977
~
-r
--
(
\
--~
(
(
\
,.,,,
{
f
I
II
f t
(
-- - -'
Figure 133-2 (Continued)
(C) The musculocutaneous
nerve is identified and (D) the transposed
intercostal nerves (dissected from a thoracic inci-
sion made just below the tip ofthe scapula) are then anastomosed
to it.9
approximately 2 in. below the coracoid process. The median
nerve is traced proximally to the lateral cord to find the
musculocutaneous nerve. The musculocutaneous nerve is
then explored to assure that it was not damaged in the orig-
inal avulsion injury.8-tO
Once the musculocutaneous nerve is isolated. the patient
is rolled into a straight lateral position. An incision is made
from the lateral border of the paraspinous muscles to the
midaxillary line just inferior to the inferior border of the
scapula. This incision is taken down through the latissimus
dorsi and serratus anterior muscles. The third through fifth
intercostal nerves are then dissected from the costal groove
-
in the inferior margin of their respective ribs as far proximal
and distal as possible. The lateral cutaneous branch of the
intercostal nerve may be identified at its takeoff just proxi-
mal to the posterior axillary line. It should be noted that the
lateral cutaneous branch might be larger than the continua-
tion of the intercostal nerve proper.
Next.a tunnel iscreated from the lateral incision to the an-
terior incision. Once the distance to the musculocutaneous
nerve is measured and a satisfactory length of intercostal
nerve has been dissected. the intercostal nerves are divided
distally and tunneled to the anterior incision. The lateral
wound is then irrigated and closed. Chest tubes may be
L
(
....
J
I
\
,.,,,
\
/
...
D

978
PeripheralNerve:Other Nerves
.
Outcomes
necessary if the pleura has been violated. After closure the
patient is again rolled back into the prone position.The mus-
culocutaneous nerve is then incised as close as possible to
the coracobrachialis muscle without putting undue tension
on the transposed intercostal nerves. The three intercostal
nerves are then sutured to the end of the transected muscu-
locutaneous nerve by 10-0 nylon. The wound is copiously
irrigated and then closed. After 6 weeks of immobilization,
passiverange-of-motion physicaltherapy may begin.8-lo
References
1.
Snell RS. Clinical Anatomy
for Medical Students.
3rd ed. Boston: Little,
Brown; 1981:63-71
2.
Netter FH.Atlas of Human Anatomy. Summit.
N]: CIBAGeigy Corpora-
tion: 1989:237-241
3.
Young RF. Dorsal
rhizotomy
and
dorsal
root
ganglionectomy.
In:
Youman's
Neurological
Surgery.
3rd ed. Philadelphia:
WB Saunders;
1990:4026-4035
4,
Brechner
VL. Management
of pain by conduction
anesthesia
tech-
niques. In: Youman's
Neurological
Surgery. 3rd ed. Philadelphia:
WB
Saunders:
1990:4007-4025
5.
Fodstad
H. Electrophrenic
respiration
after
intercostal
to phrenic
nerve anastomosis
on a patient
with anterior
spinal artery syndrome:
technical
case report. Neurosurgery
1996;38:420
6.
Krieger A].Gropper MR. Adler RJ.Electrophrenic
respiration
after inter-
costal to phrenic
nerve anastomosis
in a patient
with anterior
spinal
artery syndrome:
technical case report. Neurosurgery
1994:35:760-763
7.
Zhao S. Beuerman
RW, Kline 00.
Neurotization
of motor
nerves
in-
nervating
the
lower
extremity
by utilizing
the
lower
intercostal
nerves.]
Reconstr Microsurg
1997;13:39-45
Ifsuccessful, patients first note a return of biceps brachialis
function -8 months after surgery. Initially, the muscleac-
tion is not under voluntary control, with contractions com-
ing during coughing, but with training and observedmotor
nerve plasticity, patients can gain voluntary control,full
range of motion, and the ability to hold the arm steadily
flexed through the respiratory cycle,IO-13
8.
Yoeman P.Traction
injuries
of the brachial
plexus. In: Surgical Disor-
ders
of the
Peripheral
Nerves.
Baltimore:
Williams
and Wilkins:
1977:184-190
9.
Friedman
AH. Surgical
management
of peripheral
nerve injury and
entrapment.
Neurosurg
Clin N Am 1991 :2:165-174
10.
Friedman
AH. Nunley ]A, Goldner
RD. Nerve transposition
for the
restoration
of elbow
flexion
following
brachial
plexus avulsion in-
juries.]
Neurosurg
1990;72:59
11.
Malessy
M], Thorner
RT. Evaluation
of intercostal
to musculocuta-
neous nerve transfer
in reconstructive
brachial plexus surgery. J Neu.
rosurg 1998:88:266-271
12.
Malessy
M], van-der-Kamp
W, Thorner
RT,van-Dijk JG. Cortical ex-
citability
of the biceps
muscle
after intercostal
to musculocutaneous
nerve transfer.
Neurosurgery
1998;42:787-794
13.
Narakas AD, Hentz YR. Neurotization
in brachial plexus injuries: indi-
cation and results. Clin Orthop
1988:237:43-56

134
Surgical Management of Ilioinguinal
Neuralgia
Harsimran S. Brara
.
Anatomy and Pathogenesis
.
Indications
.
Approaches
Neuralgia of the ilioinguinal nerve usually results from in-
jury or irritation of the nerve as it courses through the
lower aspect of the anterior abdominal wall. Most cases of
ilioinguinal neuralgia occur in the postoperative setting.
Isolated cases have been reported in association with a
spinal tumor, retroperitoneal
abscess, blunt abdominal
trauma, and other more rare causes.1-3Essentialneuralgia is
becoming more rare with increased recognition of the mul-
tiple causes of the syndrome.
The surgical procedure most commonly associated with
ilioinguinal neuralgia is inguinal herniorrhaphy.1.2.4.5
Appen-
dectomy, nephrectomy,
and any procedure utilizing the
Pfannenstiel incision to gain surgical exposure can be com-
plicated by the development of ilioinguinal neuralgia.G.?
There are case reports and small clinical series of ilioin-
guinal neuralgia following iliac crest bone-graft harvests3
and as a complication
of needle bladder suspension
procedures.s Mesh inguinodynia
may represent a new
clinical syndrome with its own diagnostic and therapeutic
implications.9
Surgical intervention is reserved for refractory cases of il-
ioinguinal neuralgia. In patients for whom oral antidepres-
sant drug therapy, percutaneous anesthetic or steroid injec-
tions, and behavioral therapy have failed and the diagnosis
is assured, two surgical approaches need to be considered.
Ilioinguinal nerve groin exploration and retroperitoneal
neurectomy are surgical treatment options with known effi-
cacy in this setting.10Asurgical plan can be developed after
considering the anatomical and pathogenetic factors of each
individual case.
.
Anatomyand Pathogenesis
Ilioinguinal neuralgia most commonly results from irrita-
tion or entrapment
of the ilioinguinal nerve as it travels
through the anterior abdominal wall. A detailed under-
standing of the course of the nerve and its relationship to
muscular, bony, and visceral structures allows for a logical
and thorough differential diagnosis of ilioinguinal entrap-
ment syndromes (II).
The ventral primary divisions of L1and a variable propor-
tion contribution from T12 constitute the origin of the il-
ioinguinal nerve (Fig. 134-1). The nerve emerges from the
lateral upper border of the psoas muscle and crosses over
the anterior aspect of the quadratus lumborum and iliacus
muscles to reach the iliac crest, where it penetrates and
supplies muscular innervation to the transversus abdominis
and the internal oblique (Fig. 134-2). Acutaneous branch to
the anterolateral flank can be of substantial proportions in
cases where the iliohypogastric nerve is small and a large
contribution to the ilioinguinal nerve is derived from T12.
Importantly, the nerve does not innervate or penetrate the
external oblique muscle. Rather, it travels in the plane
between the internal and external oblique muscles to run
below the spermatic cord or round ligament. It emerges
from the superficial inguinal ring lateral to the spermatic
cord to provide sensory supply to the skin of the proximal
and medial thigh, root of the penis and upper scrotum, or
mons pubis and labium majus (Fig.134-2).
Anentrapment neuropathy encountered in the postopera-
tive setting is most commonly seen, with the reactivescar-re-
lated pathogenesis. The patient's immediate postoperative
pain evolves into a groin and medial thigh pain that is asso-
ciated with a sensory change. The patient may complain of
a dull visceral ache emanating from the iliaca and radiating
to the groin that is worse with any straining of the abdomi-
nal musculature.1.11Climbing stairs is characteristically diffi-
cult for patients with ilioinguinal neuralgia. Forwardflexion
and internal rotation of the hip are manuevers that patients
learn to find some measure of relief. The patients are most
comfortable lying on the affected side with their hips flexed
so as to diminish the stretch on the lower abdominal mus-
cles. The nerve is most commonly tethered near the ante-
rior superior iliac spine at the point where it staircases
through the muscle and fascia of the transversus abdominis
and the internal oblique.
979

980
PeripheralNerve:Other Nerves
D
C1
A
Figure 134-1
(A) Course and branches of midtho-
racic
intercostal
nerves.
(B) Lumbosacral
plexus.
schematic view.
B

134
SurgicalManagement of IlioinguinalNeuralgia
981
Direct surgical ligature is less commonly an etiologic
factor but if it is indeed the cause of the neuralgia. the
symptoms are less insidious in their onset and less re-
lieved by postural maneuvers that the typical patient de-
rives relief from a tethering
mechanism.lo Laparoscopic
herniorrhaphy held the promise of completely abolishing
the 1-2% rate of postherniorrhaphy
ilioinguinal neuralgia
due to the nature of the anatomical approach. Byremain-
ing entirely preperitoneal
and providing a tension-free
mesh repair of the anterior abdominal wall. the ilioin-
guinal nerve should not be exposed to any risk of direct
surgical ligature. A recent clinical series evaluating the
treatment
modalities
for mesh inguinodynia found an
equal incidence of postoperative
neuralgia with laparo-
scopic and open inguinal herniorrhaphy.9
On examination a Tinel's sign may be present and pres-
sure applied to the anterior abdomen near the anterior su-
perior iliac spine may reproduce or intensify the patient's
discomfort. The patient may be most comfortable lying on
the affected side with the hips flexed. Sensory testing may
demonstrate pinprick hypoesthesia or hyperesthesia. The
pattern of sensory loss may not be useful diagnostically
Figure 134-2
Anatomical relationships in the inguinal region. Note
the retroperitoneal
course on the ilioinguinal nerve.
because of the significant common areas of innervation in
the inguinal region. Medial thigh or lateral hip sensory
change can be diagnostically corroborative in localizing the
impingement syndrome
.
Indications
A patient must be accurately diagnosed with ilioinguinal
neuralgia and treated conservatively before surgical options
can be seriously considered. Percutaneous local anesthetic
injections or steroid injections can be helpful in diagnosis
and therapy of inguinal neuralgia.I,G,IO,nElectromyographic
(EMG)and nerve conduction data are corroborative but are
generally not necessary to arrive at an accurate diagnosis.
Medical treatment of neuropathic pain can be quite satis-
factory in mild cases and a trial of phenytoin. carba-
mazepine. or gabapentin may result in enduring pain relief.
A groin exploration is generally the first line of surgical
treatment. Exceptions to this general principle are patients
with a clear retroperitoneal cause for the irritation of the
ilioinguinal nerve.

982
Peripheral Nerve: Other Nerves
. Approaches
An ilioinguinal neurectomy accomplished via groin explo-
ration is the first-line treatment for the ilioinguinal neural-
gia syndrome (Table 134- t). A 6 to 8 cm oblique incision
from the anterior superior iliacspine to the pubic tubercle is
taken through the skin and subcutaneous tissues to expose
the external oblique fascia. The external oblique fascia is
opened to expose the underlying distal branches of the il-
ioinguinal nerve. There are usually two major distal
branches of the nerve that can be followed proximally to a
point deep and medial to the anterior superior iliac spine.
Transection of the nerve deep to the anterior superior iliac
spine will relieve any inguinal causes of ilioinguinal neural-
gia and is certainly the procedure of choice in the postin-
guinal herniorrhaphy setting. More distal transections of the
nerve in the groin may not accomplish the desired effect.
In cases where the ilioinguinal neuralgia originates from
entrapment of the retroperitoneal segment of the nerve, a
retroperitoneal neurectomy is appropriate (Table 134- t).
Ilioinguinal neuralgia following a retroperitoneal inflamma-
tory or infectious process and failure of a groin neurectomy
are the principal indications for a retroperitoneal
ilioin-
guinal neurectomy.I.7.IOThe patient is positioned supine
with a sandbag placed underneath the ipsilateral gluteal re-
gion so as to maximize the interval between the lower
costal margin and the iliac crest (Fig. 134-3). A4 cm inci-
sion is created just inferior to the twelfth rib in the midaxil-
lary line.The incision is taken through the external oblique,
internal oblique, and transversus abdominis muscles to ex-
pose the peritoneum.
The peritoneum
is then
swept
forward with blunt disection to expose the psoas and quad-
ratus lumborum muscles. At the lateral margin of the upper
aspect of the psoas muscle, the ilioinguinal nerve emerges
and curves over the quadratus lumborum toward the lateral
abdominal wall and the anterior superior iliac spine. The
genitofemoral nerve emerges lower and from the anterior
aspect of the psoas muscle to run inferiorly and bifurcate
Table134-1
Selectionof SurgicalApproach
IlioinguinalNerve
GroinExploration
Retroperitoneal
Neuroectomy
Postinguinal herniorrhaphy
Post-pfannensteil
incision
Post-blunt
abdominal
trauma
Post-Pott's
disease
Post-intra-abdominal
abscess
Failed prior groin exploration
References
1.
Starling JR, Hanns BA.Diagnosis
and treatment
of genitofemoral
and
ilioinguinal
neuralgia. WorldJ Surg 1989:13:586-591
2.
Kopell HP. Thompson
WA, Postel AH. Entrapment
neuropathy
ofthe
ilioinguinal
nerve. N EnglJ Med 1962:266:16-19
3.
Smith SE. Delee JC, Rarnamurthy
S. Ilioinguinal
neuralgia
following
iliac-bone
grafting.J
Bone Joint Surg Am 1984;66:1306-1308
4.
lichenstein
Il. Shulman
AG. Amid PK. Montllor
MM. Cause and pre-
vention
of postherniouhaphy
neuralgia:
a proposed
protocol
for
treatment.
AmJ Surg 1988;155:786-790
5.
Seid AS. Amos E. Entrapment
neuropathy
in laparoscopic
hemiouha-
phy. Surg Endosc 1994:8:1050-1053
6.
Sippo WC, Burghardt
A. Gomez AC. Nerve entrapment
after Pfannen-
steil incision. AmJ Obstet GynecoI1987;157:420-421
into genital and femoral brances just lateral to the iliac
vessels.
A4 to 5 cm segment of the most proximal portionofthe
ilioinguinal nerve is resected after anatomical localization.
Thetwo-sectionedends are burried intothe availablesur-
rounding musculature. Wound closure is accomplishedby
anatomical reapproximation of the fascial layers oftheab-
dominal wall. Any violation of the peritoneum shouldbe
detected and repaired.
Figure 134-3
Surgical positioning and incision for retoperitoneal
neurectomy.
7.
Stulz P,PfeifferKM.Peripheral nerve injuries resulting fromcommon
surgical procedures in the lower portion of the abdomen. ArchSurg
1982;117:324-327
8.
Monga
M, Ghoneim
GM. Ilioinguinal
nerve
entrapment
following
needle bladder
suspension
procedures.
Urology 1994:44:447-450
9.
Heise CP,Starling JR. Mesh inguinodynia:
a new clinical syndrome af-
ter inguinal
herniorrhaphy?
J Am Coil Surg. 1998:187:514-518
10. Hahn l. Clinical findings and results of operative treatment in ilioin-
guinal
nerve entrapment
syndrome.
Br J Obstet
GynaecoI1989;96:
1080-1083
11.
Starling
JR, Harms
BA. Schroeder
ME. Eichman
Pl. Diagnosis and
treatment
of genitofemoral
and ilioinguinal
entrapment
neuralgia.
Surgery
1987:
102:581-586

135
Surgical Management of Genitofemoral
Neuralgia
Harsimran S. Brara
.
Anatomy and Pathogenesis
.
Surgical Technique
Anesthesia and Positioning
Incision and Dissection
Closure
Persistent pain and paresthesias in the inguinal region may
result from ilioinguinal or genitofemoral neuralgia.1.2Gen-
itofemoral neuralgia is rarer and has far fewer reported
cases in the world literature. Initially described by Magee
in 1942, the syndrome
is classically felt to result as a
complication of a suppurative
process in the retroperi-
toneum, most commonly a ruptured appendix.!
Gen-
itofemoral neuralgia can occur after open or laparoscopic
inguinal herniorrhaphy.3-s
Characteristically,
the
patient
suffering
from gen-
itofemoral neuralgia has been in chronic pain with near
constant
pain and paresthesias
in the inguinal region.
Hyperesthesia of the skin of the genitalia and upper me-
dial thigh is seen in the typical case. The pain is accentu-
ated
by hyperextension
of the hip and by walking.
Patients derive relief from flexion of the hip or resting in
recumbency.3.4
The major differential diagnosis of genitofemoral neu-
ralgia is ilioinguinal nerve entrapment.4 Although, both
fall under the rubric of inguinal neuralgia, it is important
to differentiate
the two for therapeutic
purposes. Both
nerves innervate areas of the groin with similar distribu-
tions, but sensory change in the upper medial thigh from
nerve endings traversing the femoral triangle of Scarpa
should be seen only in genitofemoral neuralgia. The sen-
sory change at the hip sometimes seen in ilioinguinal neu-
ralgia should not be seen in genitofemoral neuragia. A
Tinel's sign can sometimes be elicited by percussion of the
lower abdomen near the anterior superior iliac spine in il-
ioinguinal neuralgia
but is almost never seen in gen-
itofemoral neuralgia. Genitofemoral neuralgia may impair
the cremasteric reflex.
Localor specific lumbar blocks used as part of a multidis-
ciplinary conservative approach to the patient are very
helpful diagnostically. Nerve conduction and electromyo-
graphic (EMG)studies can sometimes provide useful diag-
nostic information.6
l
.
AnatomyandPathogenesis
The genitofemoral nerve is principally a sensory nerve with
a small motor component that the supplies the cremaster
muscle. The nerve arises from the first and second lumbar
roots of the lumbar plexus (Fig.135-1). The nerve descends
obliquely and pierces the fascia investing the psoas muscle
ventrally, near its medial border at the level of the third or
fourth lumbar vertebra (Fig. 135-2). It then descends sub-
peritoneally on the psoas muscle and crosses below the
ureter.
The nerve generally divides into two branches at a vari-
able level well above the inguinal ligament (Fig. 135-2). In
males, the genital branch (external spermatic) enters the in-
guinal canal at the deep inguinal ring and supplies the cre-
master muscle and the scrotal skin. In women, the genital
branch accompanies the round ligament through the deep
inguinal ring and conveys sensory information from the
mons pubis and labium majus. The femoral branch (lum-
boinguinal) descends lateral to the external iliac artery and
passes anterior to the deep circumflex iliac artery and deep
to the inguinal ligament to assume a lateral position within
the femoral sheath. Byexiting the femoral sheath and pierc-
ing the fascia lata, the femoral branch is able to conveysen-
sory information from the upper part of the femoral triangle.
The syndrome of genitofemoral neuralgia results from
nerve entrapment
that is most often due to scarring and
tethering of the nerve in a postsurgical or posttraumatic
setting.3 The syndrome is classically seen in association
with suppurative processes of the retroperitoneum. Fiveof
the seven cases described by Magee in his original descrip-
tion of the syndrome developed the signs and symptoms
after appendectomy, one patient has a psoas abscess, and
one patient has Pott's disease.! In a larger and more con-
temporary series, nine of 13 patients with genitofemoral
neuralgia
had developed
the syndrome after inguinal
herniorrhaphy.3
983

984
PeripheralNerve:Other Nerves
Figure 135-1
Schematic view of the lumbar plexus.
The syndrome ofgenitofemoral neuralgia is unlikeilioin-
guinal neuralgia in that a groin exploration and proximal
neurectomy within the groin wound are far less likelytobe
successful. The only real surgical option for genitofemoral
neuralgia is the retroperitoneal neurectomy.3.4
.
Surgical Technique
Anesthesia and Positioning
General anesthesia is administered and the patient isposi-
tioned supineon the operatingtablewithasandbagplaced
under the hip ofthe operativeside.Thispositioningopens
the interval between the lower costal margin and the iliac
crest (Fig.135-3).
Incision and Dissection
The incision is made from the lateral aspect of the rectus
sheath to the anterior axillary line at a level slightlyrostral
to the umbilicus. The external oblique and internal oblique
muscles are divided to provide access to the tranversusab-
dominis. which is divided in line with its fibers to expose
Figure 135-2
Retroperitoneal course of the genitofemoral nerve. Note the inguinal relationships ofthe genitofemoral nerve.

135
SurgicalManagement of Genitofemoral Neuralgia
985
Figure 135-3
Positioning for retroperitoneal neurectomy.
References
1. Magee RK. Genitofemoral
causalgia (a new syndrome).
Can Med
AssocJ 1942;46:326
2.
Lyon EK.Genitofemoral causalgia. Can Med AssocJ 1945;53:213
3.
Harms BA. DeHaas DR.Starling JR.Diagnosis and management of gen-
itofemoral neuralgia. Arch Surg 1984;339-341
4.
Starling JR.Harms BA. Diagnosis and treatment of genitofemoral and
ilioinguinal
entrapment
neuralgia. World J Surg 1989;13:586-591
the transversalis fascia. Division of this fascia allows for
entry into the retroperitoneum. The peritoneum and preperi-
toneal fat are swept anteriorly with blunt dissection to
expose the psoas and quadratus lumborum muscle. The
ureter is identified and safeguarded.
The genitofemoral nerve is seen exiting from the sub-
stance of the psoas muscle at its medial border at approxi-
mately the level of the third or fourth lumbar vertebra. The
course of the nerve into the pelvis in an oblique fashion to
divide into its two main branches at a variable level usually
above the level of the inguinal ligament. Once the nerve has
been unequivocally identified and dissected over a 5 to 6
cm span, it should be divided with electocautery,
the
stumps buried in muscle, and the resected segment submit-
ted for pathological examination.
Closure
Wound closure is then accomplished in layers by first clos-
ing any violation of the peritoneal lining that may have
occurred. The fascial layers of the transversus abdominis,
internal oblique, and external oblique muscles are then
closed with a running absorbable suture.
Patients can generally be discharged on the second post-
operative day once they have normalized their diets and
activity.
5.
Seid AS.Amos E. Entrapment neuropathy in laparoscopic herniorrha-
phy. Surg Endosc 1994;8:1050-1053
6.
laha RK. Rao S. Pidgeon CN, Dujovny
M. Genitofemoral
neuralgia.
Surg Neuro11977:8:280-283

136
Lateral Femoral Cutaneous Nerve
and Intercostal Nerve
Andrew D. Fine and Wesley Faunce III
.
NeuroJogical Evaluation
. Anatomy
.
Surgical Technique
Incision and Dissection
Meralgia paresthetica is a clinical pain syndrome caused by
entrapment,
compression, or neurinoma
of the lateral
femoral cutaneous
nerve (LFCN). Conservative
nonoperative
management is successful in relieving symptoms in the ma-
jority of cases. However the surgical treatment of refractory
cases is reported to be highly successful.
First described clinically in 1878 by Martin Bernhardt,
Vladimir Roth coined the term meralgia paresthetica from
the Greek words for thigh (meros) and pain (algos) in his
1895 publication.I.2 Patients present with signs and symp-
toms including burning pain, crawling sensations of the
skin, and numbness
of the anterolateral
thigh. Though
considered a disease of adulthood, children do rarely get
meralgia paresthetica. In up to 50%of children with mer-
algia paresthetica it is bilateral.3 Hip extension and light
cutaneous stimulation of the thigh exacerbate the symp-
toms, and patients
may have an area of hair loss due
to rubbing the thigh.4 Electromyography (EMG) and so-
matosensory
evoked
potentials
(SSEPs) may support
the diagnosis.s-7 In addition 10 mLof local anesthesia at
the site of tenderness should relieve the pain. The differ-
ential
diagnosis
includes
lumbar
radiculopathy
and
femoral neuropathy. Lumbar radiculopathy
may include
motor symptoms and deep tendon reflex changes. EMG
may be useful for both femoral neuropathy and lumbar
radiculopathy.
Causes of the condition are numerous. Afew of those re-
ported include retroperitoneal tumors, tumor metastasis to
the iliac crest, tumor involving the psoas, surgical position-
ing, rapid weight loss, seat-belt
injury, open or laparo-
scopic hernia repair. diabetes, sports trauma, transfemoral
angiography, and tumor involving the lumbar vertebral
bodies.8-16Studies of adult and fetal cadavers suggest the
formation of pseudoganglia with aging as a result of erect
human posture and chronic irritation of the nerve. This
may playa role in the pathogenesis of idiopathic meralgia
paresthetica.17
986
.
Neurological Evaluation
In the series published by Williams and Trzil,277 patients
with meralgia paresthetica were treated medically.2Over
90%success was reported. The protocol in that seriesin-
cluded removal of any compressive garments, application
of ice for 30 minutes three times a day, nonsteroidal anti-
inflammatory drugs (NSAlDs)for 7 to 10 days, and elimi-
nation of exacerbating physical activity for 2 weeks.
Following this period, 50%of patients required no further
treatment. Ofthe other half, most responded to injection
of local anesthesia
and corticosteroids
at the site of
point tenderness.
This was repeated
intermittently for
symptomatic
relief. Surgery was recommended for 24
patients whose pain became disabling and refractorytoin-
jection.
They report
95% success with sectioning the
nerve.2 Other noninvasive techniques are described with
similar success.U8
. Anatomy
TheLFCNarises fromthe secondand third ventralramLlt
passes posterior to the psoas muscle, then at the lateral
border emerges to run anterior to the iliacus. It continues
a caudal course to the pelvic floor supplying the parietal
peritoneum of the iliac fossa.Toexit the pelvisthe LFCN
commonly passes beneath or through the inguinalliga-
ment medial to the anterior
superior
iliac spine and
through or anterior to the sartorius muscle (Fig. 136-1).
Its course as it exits the pelvis is variable. Variationssited
include passing several centimeters posterior to the ante-
rior superioriliacspine or as farmedialas the lateralmar-
gin of the femoral nerve. The variations are not relatedto
gender.17.19 The LFCN may leave the pelvis as up to four in-
dividual branches, or most typically, as a single nerve.20As

136
LateralFemoralCutaneousand IntercostalNerves
987
Figure 136-1
Regional anatomy and course of the lateral femoral cutaneous nerve.
it enters the thigh it divides into the anterior and posterior
branches. The posterior branch emerges first from the fas-
cia lata then divides and supplies the skin on the lateral
leg from the greater trochanter
superiorly to midthigh.
The anterior branch reaches the subcutaneous tissues -10
cm distal to the anterior superior iliac spine and supplies
the skin of the anterior and lateral thigh to the knee inferi-
orly.At the knee it contributes to the patellar plexus along
with terminal
cutaneous
branches of the femoral and
saphenous nerves. A large anatomical human cadaveric
study revealed five common variations. The nerve may en-
ter the thigh posterior to the anterior superior iliac spine
in 4%,within the substance of the inguinal ligament in
27%,and ensheathed in the tendinous origin of the sarto-
rius muscle in 23%.These three patterns were felt to be at
greater risk of mechanical injury. Twenty-six percent ex-
ited the pelvis medial to the tendon of the sartorius mus-
cle and lateral to the thick fascia of the iliopsoas muscle
beneath the inguinal ligament. and 20%further medial in
the loose connective tissue overlying the iliopsoas fascia.21
These findings
are consistent
with
other
anatomical
reports.19
.
SurgicalTechnique
Incision
and Dissection
The patient is positioned supine under general anesthesia.
An area including the umbilicus superiorly to the midthigh
inferiorly, and the tensor fascia lata laterally to the pubic
symphysis
medially
is included
in the
sterile
field
(Fig.136-2).
Exposure of the LFCNoutside the pelvis is achieved with
a 3 cm incision parallel to and 1 to 2 cm below the lateral
margin of the inguinal ligament. The incision is carried to
the fascia lata overlying the sartorius muscle, which is then
incised parallel to the inguinal ligament. The nerve is found
medial to the anterior superior iliacspine. Asalready stated,
this may be highly variable ranging 4 cm lateral to the ante-
rior superior iliac spine to 6 cm medial.
The decision to perform nerve transection verses neu-
rolysis has been addressed
in numerous
reports.1.13.22
Some authors support neurolysis. stating philosophically
that this is a nerve entrapment syndrome and decompres-
sion should be adequate. Also, there is the potential of

988
Peripheral Nerve: Other Nerves
p
Figure 136-2
Exposure of the lateral femoral cutaneous nerve.
Patient is supine and the sterile field isshown. The skinincisionand
exposureofthe nerveare demonstrated.
preserved sensation. Others report a greater incidence of
postoperative
paresthesias
following
neurolysis
and
greater success long term with nerve transection.
More
extensive procedures including intrapelvic and suprain-
guinal approaches are reported.23 Even endoscopic tech-
niques are described.24 The recent literature
supports
transection over other techniques.2.22After stimulation to
assure the identified nerve has no motor contribution, a 4
cm section of nerve should be resected to ensure regener-
ation will not occur (Fig. 136-3). Also, any gross pathol-
ogy should be removed including constricting tissues and
neuromas. The nerve should be followed to its exit from
References
1.
Nahabedian
MY.Dellon AL.Meralgia paresthetica:
etiology. diagnosis.
and outcome
of surgical
decompression.
Ann Plast Surg 1995;35:
590-594
2.
Williams
PH. Trzil KP. Management
of meralgia
paresthetica
Isee
comments).J
Neurosurg
1991 ;74:76-80
3.
Edelson
R. Stevens P. Meralgia
paresthetica
in children.
J Bone Joint
Surg Am 1994;76:993-999
4.
Aranoff SM. Levy HB. Tuchman
AJ. et al. Alopecia
in meralgia
pares-
thetica.J
Am Acad DermatoI1985;12:176-178
5.
Butler IT. Johnson
EW. Kaye ZA. Normal
conduction
velocity
in the
lateral
femoral
cutaneous
nerve.
Arch Phys Med Rehabil
1974;55:
31-32
6.
Po HL. Mei SN. Meralgia
paresthetica:
the diagnostic
value
of so-
matosensory
evoked potentials. Arch Phys Med Rehabil1992:73:70-72
7.
Sarala PK. Nishihara
T. Oh SJ. Meralgia
paresthetica:
electrophysio-
logic study. Arch Phys Med Rehabil1979:60:30-31
8.
Amoiridis
G. Wohrle
J. Grunwald
I. et al. Malignant
tumour
of the
psoas:
another
cause of meralgia
paraesthetica.
Electromyogr
Clin
NeurophysioI1993;33:109-112
Rgure 136-3
The nerve istransected and followed to the inguinallig-
ament to preventtethering and neuromaformationatthe skinincision.
the pelvis such that it does not become tethered at the in-
guinalligament.
The clinical importance of the LFCNis not limitedto
treatment
of meralgia
paresthetica.
It may be selectively
blocked using a nerve stimulator for skin anesthesiaduring
a muscle biopsy and superficial
procedures.2s-27 Dibbellet
al describe
a technique
for supplying
the skin over the
ischial
tuberosity
with
sensation
in
patients
with
myelomeningocele utilizing an extended fascia lata flap.
This is important
in preventing
or healing pressure sores.28
Asimilar case is reported with 4 years' follow-upinapara-
plegic patient.29.3o
9.
Baldini
M. Raimondi
PL. Princi L. Meralgia
paraesthetica
following
weight
loss. Case report. Neurosurg
Rev 1982;5:45-47
10.
Eubanks
S. Newman
L. Goehring
L. et al. Meralgia
paresthetica: a
complication
of laparoscopic
herniorrhaphy.
Surg Laparosc Endosc
1993;3:381-385
11.
Kahn L. Neuropathies
masquerading
as an epidural complication. Can
J Anaesth
1997;44:313-316
12.
Lorei MP. Hershman
EB. Peripheral
nerve injuries
in athletes: treat-
ment and prevention.
Sports Med 1993;16:130-147
13.
Moscona
AR. Sekel R. Posttraumatic
meralgia
paresthetica:
an un-
usual presentation.
J Trauma 1978: 18:288
14.
Parsonnet V.Karasakalides A.Gielchinsky I.et al. Meralgia parestheticaaf-
ter coronary bypass surgery. J Thorac Cardiovasc Surg 1991:101:219-221
15.
Rinkel GJ.Wokke JH. Meralgia paraesthetica
as the first symptom ofa
metastatic
tumor
in
the
lumbar
spine.
Clin
Neurol
Neurosurg
1990;92:365-367
16.
Tharion
G. Bhattacharji
S. Malignant
secondary
deposit
in the iliac
crest masquerading
as meralgia
paresthetica.
Arch Phys Med Rehabil
1997:78:1010-1011

...
136
LateralFemoralCutaneousand IntercostalNerves
989
17. EdelsonJG.Nathan H. Meralgia paresthetica: an anatomical interpre-
tation. Clin Orthop
1977:255-262
18.
Kadel RE.Godbey WD, Davis BP.Conservative and chiropractic
treat-
ment of meralgia paresthetica: review and case report. JManipulative
Physiol Ther 1982:5:73-78
19.
Dibenedetto
LM, Lei Q, Gilroy AM, et al. Variations
in the inferior
pelvic pathway of the lateral femoral cutaneous nerve: implications
for laparoscopic hernia repair. Clin Anat 1996:9:232-236
20.
Surucu HS,Tanyeli E.Sargon MF, et al. An anatomic study of the lat-
eral femoral cutaneous nerve. Surg Radiol Anat 1997:19:307-310
21. Aszmann OC.Dellon ES,Dellon AL. Anatomical
course of the lateral
femoral cutaneous nerve and its susceptibility
to compression and in-
jury. Plast Reconstr Surg 1997;100:600-604
22.
van EP,Polder TW, Broere CA.Operative treatment of meralgia pares-
thetica: transection versus neurolysis. Neurosurgery 1995:37:63-65
23.
Aldrich EF,van-denHe.Suprainguinaligamentapproachfor surgical
treatment
of meralgia
paresthetica.
Technical
note. J Neurosurg
1989;70:492-494
24.
Krahenbuhl
L,Striffeler H. Baer HU, et al. Retroperitoneal endoscopic
neurectomy for nerve entrapment after hernia repair. Br J Surg 1997;
84:216-219
25.
Lang SA,Yip RW. Chang PC,et al. The femoraI3-in-1
block revisited.J
Clin Anesth 1993;5:292-296
26. Maccani RM, Wedel DJ,Melton A. et al. Femoral and lateral femoral
cutaneous
nerve block for muscle biopsies in children. Paediatr
Anaesth 1995:5:223-227
27.
Shannon J.Lang SA, Yip RW. et al. Lateral
femoral
cutaneous
nerve
block revisited: a nerve stimulator technique. Reg Anesth 1995;20;
100-104
28.
Dibbell DG, McCraw IIi, Edstrom
LE. Providing
useful and protective
sensibility
to the sitting
area
in patients
with
meningomyelocele.
Plast Reconstr Surg 1979;64:796-799
29. Louie G, Mackinnon SE.Dellon AL. et al. Medial antebrachial cuta-
neous-lateral femoral cutaneous neurotization in restoration of sen-
sation to pressure-bearing areas in a paraplegic: a four-year follow-
up. Ann Plast Surg 1987;19:572-576
30. Mackinnon SE,Dellon AL,Patterson GA.et al. Medial antebrachial cu-
taneous- lateral femoral cutaneous neurotization to provide sensa-
tion to pressure-bearing
areas in the paraplegic
patient.
Ann Plast
Surg 1985;14:541-544

137
Nerve Graft Harvesting and Repair Techniques
R.Patrick Jacob and David A. Peace
.
NerveGrafting
.
Advantages
.
Disadvantages
.
Nerve RepairTechniques
.
HarvestingNerve Grafts
. Nerve Grafting
Many peripheral nerve procedures require the harvesting
and use of nerve interposition or cable grafts to make up
gaps in the nerve. These typically result from resection of a
neuroma in continuity, or from retraction of the severed
ends of a complete neurotmetic injury. The need for a cable
graft in nerve repair is present when a nerve anastomosis is
under any tension at the suture site. Distractive forces at a
suture site will characteristically cause separation of the
proximal and distal repair sites leading to neuroma forma-
tion and impaired or absent nerve recovery.
.
Advantages
. Enables reanastomosis across gap regions or in nerves
under tension
.
Disadvantages
. Deficitsrelatedto donornerve
. Potentialforneuromaformation
.
Nerve RepairTechniques
The first step of nerve repair is to identify areas of normal
fascicular anatomy proximal and distal to the area of in-
jury. In cases of complete neurotmesis, this typically re-
quires resection of a few millimeters to centimeters
of
scarred tissue from the ends of the nerve.! Almost all
nerve repair requires magnification, either the operating
990
microscope or high-power Ioupes, for adequate visualiza-
tion of the microanatomy. If there is a nerve gap,either
because of retraction of the nerve ends or followingre-
section of a scarred neuroma in continuity, the nerve
ends should be prepared with resection of tissueback
normal patulous fasides. It is criticalto removescarred
or nonviable tissue from the nerve ends to be suturedto
prevent neuroma formation. Normally, this can be ac-
complished with direct inspection under the microscope,
but if there is any question, a frozen-section pathological
evaluation may be performed looking for normal fasicu-
lar anatomy.
Once the nerve ends have been prepared, if the repair
site is not under any tension, a primary repair canbeper-
formed. External landmarks such as epineurial vessels
and internal fascicular arrangement can serve to orient
the nerve ends (Fig. 137- 1A).2Every reasonable effort
should be made to maintain fascicular matching foren-
hanced recovery offunction (Fig. 137-18). Theepineural
repair is accomplished
by placement of simple 8-0 or
10-0 monofilament in the external epineurallayerwith
coaptation
of the nerve ends. Care should be takento
avoid driving the needle or suture through the fascicles
(Fig. 137-2A). The sutures should not be so snug that the
ends
of the
nerve
are strangulated
or overlapping
(Fig. 137-28). The object is to bring the nerve fascicles
into
dose
apposition,
not
to achieve a watertight
epineural closure.
Thefasicularrepair is idealforuse whenmultiplecable
grafts are used in larger diameter peripheral nervesto
bridge a gap (Fig.137-3A).The grafts should be ofsufficient
length to avoid tension across the repair. The individual
grafts should be oriented appropriately tojoin proximaland
distal ends of similar fascicles. Usually two or three
monofilament sutures at each end of the graft are sufficient
for proper coaptation (Fig.137-38).