Phẫu Thuật Tạo Hình Grabb & Smith’s (Bản Cập Nhật – Kevin C. Chung)

Superficial Sensory Branch of the Radial Nerve
Radial sensory nerve entrapment in the distal forearm, also known as Wartenberg Syndrome (WS) or
cheiralgia paresthetica, presents with altered sensation and/or pain in the dorsal radial hand, a positive
Tinel sign at the site of compression, and provocation of symptoms with ulnar deviation, wrist flexion, or
resisted pronation. It is uncommon with a reported incidence of 0.003%, but it may be underdiagnosed. 45
The nerve can be compressed internally by local fascia or more distally and externally by a tight watch or
bracelet. Electrodiagnostic testing is not necessary if there is a high degree of suspicion and no proximal
symptoms. Ultrasound may demonstrate altered nerve diameter or intraneural masses.
The differential diagnosis of distal radial forearm pain is large, including de Quervain tenosynovitis,
thumb carpometacarpal osteoarthritis, lateral antebrachial cutaneous neuritis, intersection syndrome, and
proximal nerve compression. 46 Dorsal-radial wrist/hand pain that responds to a nerve block will reliably
respond to surgical decompression. WS mimics de Quervain tenosynovitis but does not improve with a
steroid injection to the first dorsal extensor compartment, a clue to the diagnosis.
Nonoperative treatments are immobilization with a short thumb spica splint, therapeutic ultrasound or
iontophoresis, nerve gliding exercises, or local steroid injections. Conservative therapy has been found to
have efficacy of 37% in a small patient sample at 28 months. 47 Surgical treatment is indicated for
worsening symptoms or signs of no improvement after a reasonable course of nonoperative treatment. A
longitudinal incision is made at the point of maximal tenderness along the radial forearm where the
nerve emerges from beneath fascia. Fascia is divided, and the nerve is gently freed from surrounding
tissue using tissue scissors and minimal manipulation. In 32 patients who underwent surgical release of
the radial sensory nerve, 86% experienced good to excellent outcomes. 47
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Conclusion
Upper extremity pain and dysfunction related to nerve compression is likely to be more common than
has been historically recognized. Compression of the median nerve at the wrist and ulnar nerve at the
elbow and wrist have been the most commonly recognized, but that does not mean that they are the only
nerves that can be compressed. Success has been reported following decompression of multiple motor
and cutaneous nerves, and surgeons should include this category of disorders in evaluation of the upper
extremity. Hand surgery is applied anatomy.
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Questions
1. True or false: The AIN is a pure motor nerve.
a. True
b. False
2. A construction worker develops intermittent severe pain in his both carpal tunnels with activities
involving sustained pronation of the forearms, associated with awakening with his whole hands
numb at night. Over a 10-year period, he has his carpal tunnels released three times on each side.
After each operation, he seems to have brief relief of his symptoms but as soon as he goes back to
work driving a bulldozer, fully pronated all day long, his wrists hurt, and he is dropping things. He
is sent to you by the insurance company for you to perform his seventh carpal tunnel release. Which
of the following would be included in successful treatment?
a. More physical therapy, splinting, NSAIDs
b. Repeat bilateral carpal tunnel surgery, with internal neurolysis
c. Psychiatric evaluation for depression
d. Urine test to assess for drug-seeking behavior
e. Release of the proximal median nerve
3. Which of the following anatomic structures is associated with cubital tunnel syndrome?
a. Ligament of Struthers
b. Arcade of Struthers
c. Arcade of Frohse
d. Fascia of Osborne
4. A medical student is injured during an orthopedic case when a heavy drill falls onto the middle of
her arm along the radial shaft. She has a large bruise in the midforearm that resolves, but weeks later
she has persistent pain in the radial wrist, particularly with combined thumb adduction and ulnar
deviation of the wrist. There is no tenderness or swelling at the radial styloid. She has no response to
NSAIDs, or steroid injection into the tendon sheath at the wrist. A thumb spica splint helps to
prevent the pain but is very uncomfortable to wear and makes it hard for her to perform her duties
on the orthopedic service. What would the next step be?
a. Physical therapy for strengthening exercises
b. Surgical release of her first dorsal extensor compartment
c. Cognitive behavioral therapy for disproportionate pain
d. Blocking of the superficial sensory branch of the radial nerve with local anesthesia
5. A 50-year-old hospital administrator develops swine flu, followed by severe shoulder pain. On
recovery, several weeks later, he notes difficulty pulling his zipper up and buttoning his shirt. On
exam, he is noted to have no active flexion of this thumb IP joint and index finger DIP joint. What is
the diagnosis?
a. Neuralgic amyotrophy (Parsonage Turner syndrome)
b. PMNE
c. Lou Gehrig disease (amyotrophic lateral sclerosis)
d. Flexor tendon ruptures of the FPL and FDP IF
e. Stenosing tenosynovitis of the thumb and index finger
1. Answer: b. Although there are literally hundreds of descriptions of the AIN as a “pure motor
nerve” in medical literature, it is not a pure motor nerve. The AIN is a motor nerve to the FPL, FDP
IF, and PQ, and terminates in a large sensory nerve to the volar wrist bones. Compression of the AIN
branch of the median nerve at the elbow can cause referred pain in the volar wrist/distal volar
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forearm. Neurectomy of the sensory branch of the AIN is performed to denervate the wrist, useful
for painful wrist conditions that are not reconstructable.
2. Answer: e. Recurrent or persistent CTSs are rare following carpal tunnel release if the diagnosis is
correct and the surgery was performed with proper technique. Wrist pain with sustained pronation
in this example is explained by pressure on the sensory branch of the AIN by the deep fascia of the
ulnar origin of the pronator teres muscle. Failed carpal tunnel surgery can represent anatomic
variation, technical error, excessive scar formation, malingering, somatization, or failure to
appreciate a more proximal site of compression that causes very similar symptoms. Electrodiagnostic
studies are often ordered to assess patients for PMNE but are rarely helpful.
3. Answer: d. Also referred to as the ligament of Osborne, these fascial fibers connect the two heads
of the FCU muscle just distal to the interval between the medial epicondyle and the tip of the
olecranon, and can flatten the ulnar nerve within the cubital tunnel. The Ligament of Struthers is an
anatomic variant that connects the humerus to the medial epicondyle and can cause proximal
median nerve compression. The arcade of Frohse is the proximal fascial arch of the supinator, which
lies superficial to the PIN in the radial tunnel. The arcade of Struthers is a vascular leash that crosses
the median nerve in the upper arm.
4. Answer: d. Wartenberg syndrome is a focal neuritis of the superficial sensory branch of the radial
nerve, often associated with local trauma. The radial sensory nerve exits between the extensor carpi
radialis longus and the brachioradialis as it travels from deep to superficial, and it is particularly
vulnerable to blunt trauma along the distal radial shaft, where scar tissue can tether the nerve. The
pain from Wartenberg syndrome mimics the pain from de Quervain tenosynovitis.
5. Answer: a. This is a classic history for neuralgic amyotrophy (Parsonage Turner syndrome): severe
pain following an inciting event such as viral illness, followed by paresis of the upper extremity.
PMNE can cause an AIN palsy if there is blunt trauma to or sustained pressure on the proximal
medial forearm for several hours. ALS is a fatal motor neuron disease that can present as hand
weakness and cramping pain, with muscle twitching and difficulty swallowing. Spontaneous tendon
ruptures are rare, but can happen after fluoroquinolone treatment, but tend to be larger tendons,
such as the Achilles tendon. Trigger fingers tend to be painful at the site of the stenosing
tenosynovitis, and active muscle contraction can be demonstrated even if the tendons are locked.
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References
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findings. J Hand Surg Am. 2010;35(4):668-677.
Rempel, D, Dahlin, L, Lundborg, G. Pathophysiology of nerve compression syndromes: response of peripheral nerves to loading. J Bone Jt
Surg Am. 1999;81:1600-1610.This broadly quoted article provides an excellent review of nerve anatomy, experimental models of compression, and the
effects of compression on the nerve in the acute, short term, and long term. The effects of vibration on nerves, the effect of gliding on the ability of the
nerve to glide, and the effects of joint position on extraneural pressure were also measured. The authors concluded that even short periods of nerve
compression can have widespread negative effects on structure and function of the nerve.
Mackinnon, SE. Pathophysiology of nerve compression. Hand Clin. 2002;18(2):231-241.
Brand, PW, Hollister, AM. Clinical Mechanics of the Hand. 3rd ed. St Louis, MO: Mosby; 1999:17-20.
Cheng, CJ, Mackinnon-Patterson, B, Beck, J, Mackinnon, SE. Scratch collapse test for evaluation of carpal and cubital tunnel syndrome. J
Hand Surg. 2008;33(9):1518-1524.The authors present a new provocative maneuver, the scratch-collapse test, to provide the surgeon with a rapid, cost-
effective, reproducible, objective test for the presence of nerve compression. The study prospectively compared the scratch-collapse test to a Tinel test and
a flexion/compression test and found it to be the most sensitive of the three at both the carpal and cubital tunnels.
Shen, L, Masih, S, Patel, DB, Matcuk, GR Jr. MR anatomy and pathology of the ulnar nerve involving the cubital tunnel and Guyon’s canal.
Clin Imag. 2016;40(2):263-274.
Chang, KV, Wu, WT, Han, DS, Ozcakar, L. Ulnar nerve cross-sectional area for the diagnosis of cubital tunnel syndrome: a meta-analysis of
ultrasonographic measurements. Arch Phys Med Rehabil. 2018;99(4):743-757.
Farooq, MU, Martin, JHW, Andary, MT. Unusual presentation of hereditary neuropathy with liability to pressure palsies. J Brachial Plexus
Periph Nerve Inj. 2008;3(1):2.
Brinkely, DM, Hepper, CT. Heart in hand: structural cardiac abnormalities that manifest as acute dysvascularity of the hand. J Hand Surg.
2010;35(12):2101-2103.
Mckee, DE, Lalonde, DH, Thoma, A, Dickson, L. Achieving the optimal epinephrine effect in wide awake hand surgery using local
anesthesia without a tourniquet. Hand. 2015;10(4):613-615.
Lalonde, DH, Bell, M, Benoit, P, et al. A multicenter prospective study of 3,110 consecutive cases of elective epinephrine use in the fingers
and hand: the Dalhousie project clinical phase. J Hand Surg Am. 2005;30(5):1061-1067.This prospective study demonstrated the safety of using
local anesthesia containing epinephrine in the hand and fingers. A brief review of the origin of the fallacy that epinephrine causes digital necrosis is
provided. This study provides compelling evidence that negates decades of medical school teaching and reminds us to be lifelong students, constantly
questioning dogma.
Hefermehl, LJ, Largo, RA, Hermanns, T, et al. Lateral temperature spread of monopolar, bipolar and ultrasonic instruments for robot-
assisted laparoscopic surgery. BJU Int. 2014;114(2):245-252.
Stanek, JJ, Renslow, MA, Kalliainen, LK. The effect of an educational program on opioid prescription patterns in hand surgery: a quality
improvement program. J Hand Surg. 2015;40(2):341-346.
Kurdi, MS, Theerth, KA, Deva, RS. Ketamine: current applications in anesthesia, pain, and critical care. Anesth Essays Res. 2014;(3):283-290.
Hustedt, JW, Chung, A, Bohl, DD, et al. Comparison of postoperative complications associated with anesthetic choice for surgery of the
hand. J Hand Surg. 2017;42(1):1-8.
Dale, AM, Harris-Adamson, C, Rempel, D, et al. Prevalence and incidence of carpal tunnel syndrome in US working populations: pooled
analysis of six prospective studies. Scand J Work Environ Health. 2013;39(5):495-505.
American Academy of Orthopaedic Surgeons. Management of Carpal Tunnel Syndrome: Evidence-Based Clinical Practice Guideline.
Published February 29, 2016. Accessed August 1, 2018.This high-quality evidence-based clinical practice guideline
represents state of the art in diagnosis and treatment of CTS at the time of its production. It is prefaced by a useful summary of graded
recommendations and was endorsed by six professional organizations.
Graham, B. The value added by electrodiagnostic testing in the diagnosis of carpal tunnel syndrome. J Bone Jt Surg Am. 2008;90A:2587-
2593.The CTS-6 model estimates the probability of presence of CTS by asking about six symptoms and signs: numbness predominantly in the
distribution of the median nerve, nocturnal numbness, thenar atrophy, positive Phalen test, loss of 2PD, and positive Tinel sign. Point values are
assigned to each, and a total of 12 or higher equates with a probability of 80% that CTS is present. Electrodiagnostic tests do not add to the probability
of making the correct diagnosis.
Andersen, JH, Thomsen, JF, Overgaard, E, et al. Computer use and carpal tunnel syndrome. JAMA. 2003;289:2963-2969.
Katz, JN, Keller, RB, Simmons, BP, et al. Maine carpal tunnel study: outcomes of operative and nonoperative therapy for carpal tunnel
syndrome in a community-based cohort. J Hand Surg. 1998;23(4):697-710.
Cook, AC, Szabo, RM, Birkholz , King, EF. Early mobilization following carpal tunnel release: a prospective randomized study. J Hand Surg.
1995;20(2):228-230.
Cobb, TK, Amadio, PC. Reoperation for carpal tunnel syndrome. Hand Clin. 1996;12:313-323.
Luria, S, Waitayawinyu, T, Trumble, T. Endoscopic revision of carpal tunnel release. Plast Reconstr Surg. 2008;121(6):2029-2034.
Hagert, E. Clinical diagnosis and wide-awake surgical treatment of proximal median nerve entrapment at the elbow: a prospective study.
Hand. 2013;8:41-46.The author reviews the history of diagnosis and treatment of PMNE and presents her treatment paradigm. Rather than using a
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large incision, she proposes releasing the lacertus fibrosus with a small proximal forearm incision under local anesthesia. In a prospective study, 44
patients underwent surgery. At the 6-month point, significant improvements were seen in the quick DASH, work DASH, and activity DASH. visual
analog scale scores of minimal numbness, almost pain, and high satisfaction were also found.
Casey, PJ, Moed, BR. Fractures of the forearm complicated by palsy of the anterior interosseous nerve caused by a constrictive dressing: a
report of four cases. J Bone Jt Surg Am. 1997;79A:122-124.
Chi, Y, Harness, NG. Anterior interosseous nerve syndrome. J Hand Surg. 2010;35(12):2078-2080.
Parsonage, MJ, Turner, JWA. Neuralgic amyotrophy: the shoulder-girdle syndrome. Lancet. 1948;1:973-978.
Kiloh, LG, Nevin, S. Isolated neuritis of the anterior interosseous nerve. BMJ. 1952;1:850-851.
Garrett, JP, Cole, DW, Ruch, DS. Measurement of intraoperative nerve conduction velocities during anterior interosseous nerve
decompression. Am J Orthop. 2007;36(12):675-677.
Mystakidou, K, Parpa, E, Tsilika, E, et al. Comparison of pain quality descriptors in cancer patients with nociceptive and neuropathic pain. In
Vivo. 2007;21:93-98.
Rowland, LP, Shneider, NA. Amyotrophic lateral sclerosis. N Engl J Med. 2001;344(22):1688-1700.
Padua, L, Aprile, I, Caliandro, P, et al. Natural history of ulnar entrapment at elbow. Clin Neurophysiol. 2002;113(12):1980-1984.
Chimenti, PC, Hammert, WC. Ulnar neuropathy at the elbow: an evidence-based algorithm. Hand Clin. 2013;29:435-442.
Malay, S; SUN Study Group ; Chung, KC. The minimal clinically important difference after simple decompression for ulnar neuropathy at
the elbow. J Hand Surg Am. 2013;38(4):652-659.
Jariwala, A, Bansal, N, Nicol, GM, et al. Outcome analysis of cubital tunnel decompression. Scott Med J. 2015;60(3):136-140.
Bachoura, A, Jacoby, SM. Ulnar tunnel syndrome. Orthop Clin North Am. 2012;43:467-474.
Mondelli, M, Ginanneschi, F, Rossi, A. Evidence of improvement in distal conduction of ulnar nerve sensory fibers after carpal tunnel
release. Neurosurgery. 2009;65(4):696-700.
Kaiser, R, Houšťava, L, Brzezny, R, Haninec, P. The results of ulnar nerve decompression in Guyon’s canal syndrome. Acta Chir Orthop
Traumatol Cech. 2012;79(3):243-248.
Shah, A, Jebson, PJL. Current treatment of radial nerve palsy following fracture of the humeral shaft. J Hand Surg. 2008;33(8):1433-1434.
Moradi, A, Ebrahimzadeh, MH, Jupiter, JB. Radial tunnel syndrome, diagnostic and treatment dilemma. Arch Bone Jt Surg. 2015;3(3):156-162.
Calfee, RP, Patel, A, DaSilva, MF, Akelman, E. Management of lateral epicondylitis: current concepts. J Am Acad Orthop Surg. 2008;16(1):19-
29.
Sigamoney, KV, Rashid, A, Ng, CY. Management of atraumatic posterior interosseous nerve palsy. J Hand Surg. 2017;42(10):826-830.
Spinner, M. The arcade of Frohse and its relationship to posterior interosseous nerve paralysis. J Bone Jt Surg Br. 1968;50B:809-812.
Dang, AC, Rodner, CM. Unusual compression neuropathies of the forearm. Part 1: radial nerve. J Hand Surg. 2009;34(10):1906-1914.
Ponnappan, RK, Khan, M, Matzon, JL, et al. Clinical differentiation of upper extremity pain etiologies. J Am Acad Orthop Surg. 2015;23(8):492-
500.
Dellon, AL, Mackinnon, SE. Radial sensory nerve entrapment in the forearm. J Hand Surg Am. 1986;11(2):199-205.
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C H A P T E R 7 1
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Principles and Applications of Nerve Transfers
Gwendolyn Hoben and Alison K. Snyder-Warwick
Key Points
Nerve transfers are an evidence-based, reliable, and effective reconstructive tool for both motor and
sensory deficits.
Major indications for nerve transfer include
Proximal nerve stump not available (i.e., congenital etiology, root avulsion, hypoplasia,
intracranial)
Distance to target is prohibitive to recovery (i.e., proximal nerve injury of the upper extremity or
late presentation following injury)
The timeline of muscle atrophy must still be respected with nerve transfers; plan transfers to consider
distance of transfer to target and time from injury.
Donor nerves should be strong, redundant/expendable, modality matched (motor to motor, sensory
to sensory), close to target, and preferably synergistic.
Sensory nerve transfers and tetraplegia transfers (upper motor neuron injury) are exceptions to the
timeline used for motor reinnervation.
When performing a nerve transfer, follow the mantra, Donor distal, recipient proximal to guide
dissection and transection.
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Why Nerve Transfers?
History
Nerve transfers arose from the natural evolution of inadequate treatment options for patients with nerve
injury. Although Ballance published a description of side-to-end nerve transfer of the spinal accessory
nerve to the injured facial nerve in 1903, the concept of nerve transfers was accelerated by the injuries
seen in World War I. World War I resulted in increased numbers of challenging nerve injuries,
particularly gunshot wounds, for which management was inadequate. A German neurophysiologist, self-
taught neurosurgeon, and translational neuroscientist, Otfrid Foerster, pushed the envelope of
management for his patients with nerve injuries in the quest to achieve better outcomes. He performed
three types of nerve transfers 1 :
End-to-end (he called copulation)
End-to-side (he called inoculation) with the inclusion of reverse end-to-side transfers, which we today
call supercharge
Partial nerve transfers of up to 30% of the donor nerve diameter (he called Abspaltung), analogous to
today’s fascicular transfers
Foerster reported on over 15 nerve transfers in 1929, emphasized the importance of postoperative
rehabilitation and follow-up, and described neural plasticity. Although many of his techniques were
forgotten or abandoned for decades, the roots of the recent paradigm shift to nerve transfers for nerve
injury management, which has witnessed exponential growth, lie in Foerster’s work in the early 1900s.
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An Open Door
Nerve transfers have gained popularity due to the shortcomings of previous nerve injury management
options. Before nerve transfers, options included primary nerve repair or nerve grafting. Although these
options are ideal and preferred for some nerve injuries, multiple clinical scenarios, such as proximal
nerve injuries, injuries located distant from their target muscle, and injuries in which no proximal nerve
stump is available (e.g., root avulsion, trauma), to name a few, are not amenable to direct repair or nerve
grafting. To fulfill this clinical management gap, nerve transfers have come into existence and gained
acceptance. Nerve transfers differ substantially from nerve autografts (Table 71.1). Nerve transfers have
the distinct advantage to provide neural reconstruction in close proximity to the end target muscle,
thereby eliminating the need to reenter the zone of injury and promoting faster recovery, which equates
to improved functional outcome. Because nerve injuries occur in all body regions, nerve transfers, too, are
not limited to any one anatomic area, but may be performed throughout the body.
TABLE 71.1
Nerve Grafts Versus Nerve Transfers
Advantages
Disadvantages
Nerve grafts
Reconstruct like with like
Little to no motor reeducation
Spontaneous, emotional movement (for face)
Requires donor site
May be long
Involves coaptations
Recovery may be less robust
Nerve transfers
Closer to target
Avoid additional coaptations
Avoid potential graft harvest from distant site
May be stronger axonal input
Can be use when proximal nerve stump not available
Avoid need to reenter zone of injury
Require motor reeducation
May involve unwanted movements
Movement may not be spontaneous
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Basic Principles
The Injured Nerve
Once the decision has been made that a nerve transfer is appropriate, in the case of traumatic proximal
injuries, the proximal injury may still be addressed. There are two critical reasons for this: pain control
and sensory reconstruction. An unrepaired major nerve injury may result in neuroma formation and
potentially debilitating neuropathic pain. Depending on the length of the nerve gap and other
reconstructive needs, use of nerve autografts, venous conduits, or acellular nerve allografts are reasonable
options to provide a regenerative pathway and prevent neuroma formation. Muscles will atrophy if not
reinnervated within 12 to 18 months, but the time frame for sensory regeneration is longer, but not well
known. The prognosis for sensory recovery likely declines over time due to mechanisms less well
understood than the atrophy of the neuromuscular junction in motor nerves; however, sensory nerve
transfers have been successful 20 years after injury and at significant distance to the target.
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Indications for Nerve Transfer
Nerve transfers have enabled robust functional recovery in challenging circumstances. Distance and time
from injury are the main barriers to functional reconstruction. Nerve transfers enable rapid and successful
reinnervation, even when patients present late. They also enable reconstruction when no proximal stump
of the injured nerve is available, when a large zone of injury exists, or when the exact location of injury is
unknown. Successful reconstructions, like with tendon transfer, require supple joints and careful donor
planning. The indications for nerve transfer include
Injury distant from target
Proximal nerve stump not available (e.g., intracranial VII, avulsed brachial plexus root)
Large zone of injury
Segmental or multiple nerve injuries
Unknown location of nerve injury
Partial nerve injuries
Zone of injury adjacent to critical structures
Prolonged time from injury
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Donor and Recipient Nerve Selection
Similar to tendon transfers, the donor nerve should be selected based on specific characteristics.
The criteria for donor nerve selection are as follows:
Functioning or recovering donor
Redundant function (expendable)
Synergistic movement
Similar power
Proximity to target muscle
Reconstruct motor with motor and sensory with sensory
A logical requirement is that the donor nerve be intact and uninjured. There are instances, however,
when a recovering nerve may be utilized. In devastating multinerve injuries or cervical spinal cord
injuries, it may be reasonable to use a recovering nerve closer to the injury site to transfer to a nerve more
distally to reduce the regeneration distance. In the case of tetraplegia, the zone of injury can include lower
motor neuron injuries that will recover, and those nerves could be transferred because donor nerves are
scarce and may be utilized for a more critical hand function. Clearly, the donor should also be redundant,
to avoid functional sacrifice. In contrast to tendon transfers, there are often multiple nerve fascicles going
to a single muscle, and transfer of a single fascicle may still retain donor function. Modality specificity
(i.e., reconstructing motor with motor and sensory with sensory) is important for improved outcomes. It
is intuitive to attempt to match the axonal number in the donor nerve to that of the recipient, similar to
the way donor tendons should match the power and excursion of the recipient. There is strong evidence,
however, that a definable minimum number of axons will lead to equivalent functional reinnervation.
Animal studies indicate regeneration of only 12% to 30% of the native axons leads to motor function
equivalent to preinjury function. 2 Schreiber et al. compared outcomes and donor-recipient axon matches
in nerve transfers for elbow flexion and found a minimum donor to recipient ratio of 0.7 predictive of
good function. 3 Terzis et al. found that donor nerves with over 74% the number of axons in the target
nerve led to improved outcomes in cross-facial nerve grafts for facial palsy. 4 In contrast, several
examinations of the number of intercostal nerves transferred to the musculocutaneous nerve did not
show improving function with additional nerves transferred. Rather, transfers representing roughly two-
thirds the number of axons of the musculocutaneous nerve fared no better than those representing one-
third the axon number. 5 Maximizing function and reducing donor burden is an ongoing area of research.
Motor retraining must also be considered when choosing the donor nerve. For example, in patients with
injury to the musculocutaneous nerve and loss of elbow flexion, described transfers use either a flexor
digitorum superficialis (FDS) branch or a fascicle of flexor carpi ulnaris (FCU) to transfer to the biceps.
Considering that the biceps is a supinating muscle and that the median nerve controls pronation, this
coaptation is antagonistic and retraining is easier with an ulnar fascicle from the FCU. While preferred,
this advantage should not limit reconstruction. In pan-plexus injuries, unrelated donors are often the only
option and can be successful. For example, during initial retraining following intercostal nerve transfers
to the biceps, the patient must learn to inhale to initiate elbow flexion. Over time, however, full voluntary
control is possible irrespective of breathing patterns. Excellent cortical plasticity in children often enables
motor reeducation of the transferred nerve without learned tricks. Indeed, transfers from the phrenic
nerve to the brachial plexus in the setting of birth-related brachial plexus palsy have very good outcomes
despite completely disparate prior functions.
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Nerve Transfer Coaptations
The general tenants of nerve repair apply to nerve transfers. The coaptation should be tension-free; the
donor nerve should be dissected as far distally as possible to maximize length, and the recipient nerve
must be divided as proximally as reasonable. We use the mantra, donor distal, recipient proximal. It may be
intuitive to place the repair distal on the recipient nerve to shorten the distance to the target, but a repair
with excessive tension risks poor outcomes. The extremity should be able to move through full range of
motion without tension on the coaptation.
Another critical consideration is whether the coaptation should be end-to-end (ETE) or end-to-side (ETS).
In ETE repairs, both the recipient and donor nerves are divided and coapted, such that neither the
recipient nor donor nerve is left in continuity. When the donor nerve is left in continuity and the recipient
end is coapted into the side of the donor nerve, these are classically considered ETS or terminolateral
coaptations (Figure 71.1). The most significant advantage of ETS is that donor morbidity is minimized. In
this technique, an epineurial window is cut in the donor nerve to facilitate regeneration into the recipient
nerve. Many animal studies have confirmed that lateral sprouting from the donor nerve repopulates the
recipient nerve without donor morbidity. 6,7 Use of ETS has been studied clinically in facial nerve
reconstruction; an intact hypoglossal donor nerve significantly reduces tongue atrophy with excellent
facial nerve function. 8 In the upper extremity, there are case reports of M3 elbow function after coapting
an avulsed musculocutaneous nerve to the intact median nerve and of reasonable outcomes following
digital nerve ETS repairs. ETS is useful when donor nerves are scarce. For this reason, ETS transfers have
been increasingly used to reconstruct birth-related brachial plexus injuries.
FIGURE 71.1 Types of nerve transfer coaptations. Neural coaptation for nerve transfers may be performed via end-to-end
(ETE, left), end-to-side (ETS, center), or reverse ETS or supercharge (right) techniques. Both donor and recipient nerves are
transected for ETE transfers. Donor nerves remain intact for ETS transfers, and recipient nerves remain in continuity in reverse
ETS, or supercharge, transfers.
In contrast, reverse ETS or supercharge ETS indicates leaving the recipient nerve intact and coapting the
proximal end of the donor nerve to the side of the recipient nerve (see Figure 71.1). This technique is
particularly advantageous when a large mixed motor and sensory nerve is injured proximally and
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repaired; preserving continuity of the nerve may allow for sensory regeneration over months to years,
whereas the transfer allows motor reinnervation prior to loss of motor endplates. For example, proximal
ulnar nerve injuries have a poor prognosis for intrinsic muscle function because the time for regeneration
is over 18 months. Sacrifice of the anterior interosseous nerve (AIN) end into the side of the deep ulnar
motor branch achieves more rapid intrinsic muscle reinnervation while allowing for sensory regeneration
to proceed distally in the ulnar nerve. These reverse or supercharge ETS repairs show augmented
regeneration into the recipient nerve in animal models 9 and improved regeneration in clinical
application. 10 Current research is examining side-to-side coaptations to harness the advantages of both
ETS and reverse/supercharge ETS. 11 A supercharge transfer is useful in the scenario of partial nerve
injuries. For example, in a partial ulnar injury where electrodiagnostic studies indicate axons in continuity
to muscles, but severely reduced in number, the nerve transfer can serve to augment the number of axons
supplying those critical muscles and promote a greater functional outcome without sacrificing the axons
still in continuity.
Confusion exists regarding terminology related to nerve coaptations. As summarized by Dellon et al.,
describing nerve coaptations in the direction of axonal regeneration may improve clarity. 12 An ETS
repair, then, would indicate that the donor nerve is transected and repaired to the side of the injured
recipient nerve, which is in actuality a reverse ETS, or supercharge transfer. The term ETS, however, is
often used to describe all terminolateral repairs. The classic ETS repair in which the transected end of the
recipient nerve is coapted to the side of the donor nerve is in actuality a side-to-end repair. Although we
are not able to settle the inconsistencies in terminology reported in the literature, it is important to take
detailed note of the scenarios described.
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Babysitter Procedures
Babysitter nerve transfers are used to temporarily maintain recipient muscles and may challenge the
standard modality matching in donor and recipient nerve selection. This chapter focuses on transfers
designed to restore volitional motor control or normal sensation. In these scenarios, the transfers are
modality matched: motor to motor and sensory to sensory, and permanent. In scenarios requiring
regeneration over very long distances, however, such as cross-facial nerve grafts or extensive brachial
plexus grafting, or in cases of delayed treatment, preserving recipient muscle motor endplates is critical to
successful eventual regeneration. As first coined in 1984 by Terzis, the first stage of a babysitter procedure
for facial palsy involves coapting cross-face nerve grafts to the functional, contralateral facial nerve
branches (the distal graft ends were left free). On the injured side of the face, 40% of the hypoglossal
nerve is transferred to the critical branches of the nonfunctional facial nerve. In the second stage, 8 to
12 months later, the free ends of the cross-face grafts are connected to the distal stumps of the injured
facial nerve and the mini hypoglossal nerve transfer is left intact. The intervening hypoglossal transfer
preserved the facial mimetic muscle motor endplates, while regeneration proceeded through the cross-
facial grafts. 13 Since then, variants on this procedure have evolved, including use of noncritical sensory
nerves to maintain muscle mass or to improve axonal regeneration in long nerve grafts. Animal studies
have shown that both sensory and motor nerves can be utilized to preserve muscle mass. 14,15 In the
scenario of long nerve grafts, sensory nerve transfers are considered to maintain or improve the pathway.
For example, Placheta et al. showed that sensory nerve coaptations into the side of long cross-face grafts
in rats increased the number of regenerating motor axons and resulted in improved functional outcomes.
16
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Applications
Face
Motor
Nerve transfers for reconstruction of facial expression may be performed if conditions are favorable for
reinnervation of the native mimetic muscle. Facial muscle differs from skeletal muscle and is thought to
have a longer reinnervation window, considered to be up to 12 to 24 months after injury. Each branch of
the facial nerve should be assessed for function. Reconstruction may be performed for a specific
movement, or more globally for tone or multiple movements. Two of the most integral movements for
facial function are eye closure and smile, and these movements should be the focus of reconstruction. The
masseteric nerve is likely the most commonly used donor nerve for transfer given its proximity within
the ipsilateral cheek, its robust axonal supply, 17,18 and reliable location. 19,20 The advantages of the
masseteric nerve include
Robust axonal supply
Ability to be transferred without a graft
Reliable location
Low donor site morbidity
Postoperatively, there is the challenge of motor reeducation. Use of the masseteric nerve typically results
in less spontaneous and emotional movement, although in adults who have had smile movement
powered by the masseteric nerve, 85% achieve the ability to smile without biting, with smile spontaneity
occurring routinely in 59%. 21 Transfer of the masseteric nerve to the buccal branch of the facial nerve is
commonly used for smile reconstruction (Figure 71.2). Reconstruction with the masseteric nerve does not
typically reconstruct facial tone well. 22 Use of the hypoglossal nerve has yielded greater results with
respect to resting tone. Other donor nerves for transfers to reestablish facial expression include
The deep temporal nerve 23
The platysma motor nerve (for lower lip depression) 24
C7
The phrenic nerve
The spinal accessory nerve
The mylohyoid, suprascapular, and long thoracic nerves have been suggested (based on cadaveric
studies).
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FIGURE 71.2 Masseteric to buccal nerve transfer. The distal end of the buccal branch of the facial nerve can be tunneled
through the parotid parenchyma, if needed, to allow direct coaptation without the need for an interposition graft. The masseteric
nerve is located on the deep surface of the masseter muscle at a point 3 cm anterior to the tragus and 1 cm inferior to the
inferior border of the zygomatic arch. Both nerves are shown here before transection for an end-to-end repair.
Differential innervation of separate facial movements can decrease unnatural mass movements or
unwanted synkinetic movements. Available nerve sources should be inventoried, and the reconstructive
plan should be tailored to individual patient needs and preferences.
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Sensory
Concomitant facial paralysis with increased corneal exposure and corneal anesthesia is devastating for
corneal health and ultimately leads to ulceration, scarring, and vision loss. Regardless of facial
movement, corneal anesthesia can be reconstructed with functional regional sensory nerves. The
contralateral supraorbital and supratrochlear nerves are frequently used donors. 25,26 These nerves can be
transferred directly or via a nerve graft. After interfascicular dissection of the distal nerve end, fascicles
are tunneled in the subtenon plane and grouped three or four locations around the limbus (Figure 71.3).
The fascicles are secured and regeneration occurs into the stromal and subbasal layers of the cornea. 27
Preliminary results from patients undergoing a modified technique for corneal neurotization have been
promising—most patients regained normal sensation, with all patients achieving protective sensation. 26
FIGURE 71.3 Corneal neurotization. Corneal anesthesia can be managed by transfer of the contralateral supraorbital or
supratrochlear nerve via a sural nerve graft to the cornea. A. The nerve graft is tunnelled subcutaneously in the glabellar region
via upper lid incisions. B. Intraneural fascicular dissection allows placement of the sural fascicles at three locations adjacent to
the limbus. C. Fascicles are tunnelled in the subtenon layer and dunked into the cornea.
Facial sensory deficits may be reconstructed in a similar manner. Formal sensory mapping confirms
functionally intact, nearby nerves that may be used as donors. Branches of the trigeminal nerve can be
transferred directly or with a nerve graft to reinnervate important sensory distributions of the face. 28
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Upper Extremity Nerve Transfers
Commonly used upper extremity nerve transfers are listed in Table 71.2.
TABLE 71.2
Common Upper Extremity Nerve Transfers
Recipient Nerves and Muscle Targets
Donor Nerves
Suprascapular nerve (C5, 6)
Supraspinatus
Infraspinatus
Spinal accessory (XI)
Dorsal scapular (C3, 4, 5)
Axillary
Deltoid (C5, 6)
Radial branch to triceps (C6, 7, 8)
Medial pectoral
Musculocutaneous
Biceps (C5, 6)
Brachialis (C5, 6)
Ulnar branch to FCU (C7, 8, T1)
Median branch to FDS/FCR (C6, 7, 8, T1)
Thoracodorsal (C6, 7, 8)
Medial pectoral (C8, T1)
Radial
EPL, EDC (C7, 8)
ECRB (C6, 7, 8)
Ulnar branch to FCU (C7, 8, T1)
Median branch to FDS/FCR (C6, 7, 8, T1)
Ulnar
Intrinsics (C8, T1)
Median branch to pronator quadratus (C7, 8, T1)
Median
FPL (C7, 8, T1)
FDP (C7, 8, T1)
Thenars (C6, 7, 8, T1)
Ulnar branch to FCU (C7, 8, T1)
Radial branch to ECRB (C6, 7, 8)
Musculocutaneous branch to brachialis (C5, 6)
Ulnar to 3rd lumbrical (C8, T1)
Ulnar to abductor digiti minimi (C8, T1)
Radial to EDQ/ECU (C7, 8)
ECRB, extensor carpi radialis brevis; EDC, extensor digitorum communis; EDQ/ECU, extensor digiti quinti/extensor carpi ulnaris; FCU, flexor
carpi ulnaris; FDS/FCR, flexor digitorum superficialis/flexor carpi radialis.
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Suprascapular
The suprascapular nerve innervates the supraspinatus and infraspinatus muscles, thus providing
shoulder stability and external rotation. A stable shoulder is important for function more distally in the
upper extremity. Transfer of the spinal accessory to the suprascapular can be done either through an
anterior or posterior approach. The anterior approach combines well with a cervical approach to the
brachial plexus. A posterior approach is used to release the suprascapular notch, but does require lateral
or prone positioning. In larger patients, this dissection can be quite deep and lighted retractors are
necessary. The spinal accessory nerve has multiple branches, and the most robust branch should be used
for transfer with care to preserve branches for trapezius function. Transfer of the rhomboid nerve to
suprascapular has also been described. 29
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Axillary
Deltoid function is the most important deficit with axillary nerve injury. A branch of the radial nerve to
the triceps is facile for this transfer, and this procedure is commonly referred to as the Leechavengvong or
Somsak procedure. There are three main nerves to triceps: branches to the medial, lateral, and long heads
of the muscle. Originally, the branch to the long head of the triceps was favored, but others have argued
in favor of the medial branch because it has a longer extramuscular course. This transfer is best done in
prone position and can be combined with a spinal accessory to suprascapular nerve transfer. The medial
pectoral nerve is another donor. A metaanalysis of grafting versus nerve transfer outcomes for isolated
axillary injuries showed no significant differences between the two techniques, and most patients achieve
M4 or better shoulder abduction. 30
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Musculocutaneous
Restoration of elbow flexion is a priority in upper trunk injuries as there may be reasonably intact wrist
and hand function. There are several options depending on available donors. Transfer of an FCU branch
of the ulnar nerve to the motor nerve to biceps, referred to as an Oberlin transfer, is one of the most
commonly used and reliable nerve transfers, providing both elbow flexion and supination. 31 An FDS or
flexor carpi radialis (FCR) branch of the median nerve can also be transferred to the biceps. The double
fascicular transfer, as described by Mackinnon et al., reinnervates two elbow flexors: it combines the
Oberlin transfer with transfer of the median FDS/FCR branch to brachialis. 32 This transfer carries a
theoretical risk of eliminating both major wrist flexors. In a retrospective review, Carlsen et al. showed
that the single versus double nerve transfer resulted in similar elbow flexion strength and disabilities of
arm, shoulder, and hand (DASH) scores; the only significant difference was that the double nerve transfer
resulted in grip strength 63% of the contralateral side whereas the single nerve transfer resulted in 43%
return of grip strength. 33 Other donor options include the thoracodorsal and medial pectoral nerve. In the
scenario of complete plexus avulsion injuries, the distal spinal accessory or intercostal nerves can be used
with an interpositional nerve graft.
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Radial
Elbow extension can be restored via transfer of the nerve branch to FCU to the medial triceps. In the
hand, radial nerve function can be restored via median donors—branches to FCR and FDS, and motor
branch to pronator quadratus—transferred to posterior interosseous nerve (PIN) and extensor carpi
radialis brevis (ECRB) branches (Figure 71.4). Nerve transfer to the PIN is the only method of achieving
individual finger extension. If biceps function is intact, the PIN fascicle to supinator should be excluded
to maximize reinnervation of the more critical extensors. Although outcome studies are limited, Garcia
Lopez et al. reported on six patients who achieved M4 for wrist extension and extensor pollicis longus
(EPL) function; two-thirds also achieved M4 metacarpophalangeal extension. 34 The musculocutaneous
branch to brachialis is another possible donor. To restore radial hand sensation, lateral antebrachial
cutaneous nerve (LABC) to radial sensory can be used. However, because of nerve territory overlap in the
hand, the transfer should only be used when necessary.
FIGURE 71.4 Median to radial nerve transfers in the forearm. After proximal radial nerve injuries, transfers from the median
nerve can restore wrist extension and independent finger extension. A branch to the flexor carpi radialis (FCR), sometimes with
the palmaris longus (PL) branch as shown here, is transferred to the posterior interosseous nerve (PIN), and a flexor digitorum
superficialis (FDS) nerve branch is transferred to the extensor carpi radialis brevis (ECRB). For sensory reconstruction, the
radial sensory nerve is transferred end-to-side (ETS) in the sensory portion of the median nerve. A concomitant pronator teres
(PT) to ECRB tendon transfer is included as an internal splint.
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Ulnar
High ulnar injuries are challenging due to the long distance to the target, the ulnar intrinsic muscles.
Transfer of the median AIN branch of pronator quadratus to the motor branch of the ulnar nerve
addresses this issue and is likely one of the most commonly used transfers (Figure 71.5). In the presence
of an intact pronator teres, there is no donor deficit. Given the challenge of intrinsic recovery, even when
the ulnar nerve is in continuity, this transfer may be used in an ETS fashion. Davidge et al. showed that
ulnar supercharge transfers in the setting of traumatic injuries, severe compression, and traction injuries
resulted in M3 or better intrinsic function in 70% of patients. 10 For sensory reconstruction, the median
branch to the third webspace can be transferred. The median palmar cutaneous is another possible donor,
as is the LABC; however, this transfer usually requires a very lengthy incision, but is of high utility when
the median nerve is also damaged. Comparison of grafting versus motor and sensory transfers in
proximal ulnar nerve injuries showed significantly improved functional outcomes: 80% were at least M3
in the nerve transfer, versus 22% with grafting. Interestingly, sensory outcomes were not significantly
different with only 30% to 40% of patients reaching S3 or better at 2 years of follow-up. 35
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FIGURE 71.5 Anterior interosseous nerve (AIN) transfer to the ulnar deep motor nerve. The terminal AIN to the pronator
quadratus can be transferred to the deep motor branch of the ulnar nerve for intrinsic muscle reinnervation. Care must be taken
to coapt the AIN to the motor portion of the ulnar nerve and not the sensory region.
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Median
The most significant motor deficits in high median nerve injury are flexor pollicis longus (FPL) and flexor
digitorum profundus. An ulnar FDS branch, radial branch to ECRB, or musculocutaneous branch to
brachialis can be transferred to the AIN branch. Before reinnervation, FPL may lengthen due to
unopposed EPL pull and become less effective, thus interphalangeal extension blocking can be a helpful
adjunct during reinnervation. The median recurrent motor branch can be restored through an ulnar
motor branch to the third lumbrical, nerve to abductor digiti quinti, or a radial PIN branch to extensor
digiti quinti and extensor carpi ulnaris. Restoration of sensory function is also crucial in median injuries.
Although time is not equal to sensation loss, sensory recovery from grafts in proximal median injuries is
typically no better than S3. Transfer of the sensory digital nerve of the 4th webspace end-to-end to the
sensory component of the median nerve can be used to restore sensation in the median distribution of the
hand. In turn, sensation to the 4th webspace can be returned by coapting the distal end of the 4th
webspace sensory branch to the side of the ulnar digital nerve of the small finger.
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Flail Arm
In the scenario of a flail arm, there may be no available branches of the brachial plexus for transfer. In
these scenarios, donor nerves from the trunk must be judiciously transferred for critical functions.
Intercostal (IC) nerve or nerve to rectus transferred to the musculocutaneous nerve, either directly or with
an interposition nerve graft, can be used to restore elbow flexion or elbow extension. Given the long
distance, this transfer must be done relatively soon after injury. Most publications on IC nerve transfer
report transfer of two to four nerves, although up to seven have been reported anecdotally. Kovachevich
et al. determined that the number of complications increased significantly when four or more ICs were
transferred. 36 It is critical to assess whether the patient has had ipsilateral rib fractures or any respiratory
impairment preoperatively, such as phrenic palsy. Prior trauma will increase scarring and has been found
to increase the risk of nonviable nerves based on intraoperative stimulation. 36 The risk of iatrogenic
pneumothorax in this dissection is 9%. 36 The presence of phrenic palsy has been associated with
increased risk of respiratory compromise; however, long-term assessment of patients with combined
phrenic and intercostal nerve transfers showed no impact on respiratory function compared to phrenic
transfer alone. 37
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Birth-Related Brachial Plexus Palsy
The standard in birth-related brachial plexus palsies (BRBPP) is excision of the neuroma and grafting the
intact roots. Distal nerve transfers, however, have several advantages:
Avoid morbidity of neuroma dissection
Avoid graft donor site morbidity
Reduce distance to target muscle (especially advantageous in late presentations)Moreover, transfers
are possible in the scenario of multiple root avulsions when there are minimal donors for grafting.
The spinal accessory to suprascapular nerve transfer (Figure 71.6) was accepted early, because the
spinal accessory nerve is in the field of the standard cervical approach to the plexus. In a large
retrospective study, Tse et al. showed no significant differences in outcomes from grafting C5 to
suprascapular versus the spinal accessory transfer. They noted, however, that the transfer was more
commonly performed in more severe injuries. 38
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FIGURE 71.6 Spinal accessory nerve to suprascapular nerve transfer for shoulder external rotation. The spinal accessory
nerve is in close proximity to the suprascapular nerve. Branches to the superior trapezius muscle can be left intact to minimize
donor morbidity. The suprascapular ligament can be divided to decompress the nerve with a posterior surgical approach.
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More distal transfers such as the Oberlin transfer and radial to axillary transfers for shoulder abduction
have also been utilized in BRBPP. For the Oberlin transfer, retrospective studies have shown elbow
flexion outcomes were similar to grafting at 1 to 2 years follow-up. 39 Chang et al., however, found
improved supination with the transfer versus grafting (100 versus 19 degrees), whereas grafting resulted
in greater pronation (30 versus 0 degrees). 39 The triple transfer of spinal accessory to suprascapular,
Oberlin transfer, and radial to axillary shows improved supination and shoulder external rotation
compared to grafting. 40,41 Perhaps of greater importance, their group found no donor morbidity with the
transfers. Operative time was significantly reduced from more than 8 hours for plexus exploration and
grafting to an average of less than 3 hours for the triple transfer, and there was a concomitant drop in
length of hospital stay. 40,41 Although there have been no prospective trials of nerve transfers as primary
interventions, these results are promising.
The elephant in the room with these studies is the role of neuroma excision and grafting in sensory
outcomes. Assessments of adults with grafted BRBPP show minimal evidence of chronic pain and
remarkably good sensory function, whereas unoperated BRBPP have more mixed outcomes with some
reports of chronic pain. 42 Sole utilization of distal transfers for motor function leaves the possibility of
sensory recovery through the neuroma, but in cases of severe injury, such as avulsions, lack of proximal
reconstruction could prevent sensory recovery. Effects on development of chronic pain are unknown.
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Lower Extremity Nerve Transfers
Given the greater regeneration lengths needed in the lower extremity and the excellent outcomes of lower
extremity prosthetics, nerve transfers in the lower extremity have not progressed with same rapidity as
those in the upper extremity.
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Femoral
The femoral nerve most critically supplies the quadriceps and is responsible for knee extension.
Unfortunately, this nerve can be injured in common procedures such as total hip arthroplasty. The
anterior branch of the obturator, supplying the gracilis, adductor longus, and adductor brevis, can serve
as a donor to the femoral branches to rectus femoris and vastus medialis. The rectus femoris provides a
straight pull for knee extension whereas the medial pull of the vastus medialis balances the lateral pull of
the tensor fascia latae, innervated by the superior gluteal nerve. A case series of two patients
demonstrated Medical Research Council (MRC) 4 knee extension and hip flexion, and both patients
regained the ability to ambulate normally. 43
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Tibial
Tibial nerve function is a critical decision point for lower extremity amputation. Loss of protective
sensation to the plantar foot is linked to failure of limb salvage. The predominant motor role of the tibial
nerve is plantar flexion. In proximal tibial nerve injuries, there are multiple redundant femoral branches
to the quadriceps muscles that can be used as donors. Branches to the vastus medialis and vastus lateralis
can be transferred to the tibial branches of the gastrocnemius to return plantar flexion. This transfer is
challenging as the donor and recipient are a significant distance apart. With sufficient neurolysis of the
medial gastrocnemius branch, an ETE coaptation can be made with the donor; however, a nerve graft is
necessary to connect the vastus lateralis to the lateral gastrocnemius. In two published cases, patients
attained MRC 3/3 + gastrocnemius strength. 44 Sensation can be restored with a saphenous to tibial nerve
transfer, but the distance between these nerves requires an interposition graft. Transfer of the deep
peroneal for plantar sensation has also been successful. 45
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Peroneal
The peroneal branch of the sciatic nerve is unusually superficial and may be involved in knee dislocations
and tibial fractures. Peroneal nerve deficits result in foot drop. The tibial nerve branches to flexor
digitorum longus or flexor hallucis longus can be used as donors to the anterior tibialis to restore
extension. Few case series have been published and they vary in reported outcomes: MRC 4 or better
outcomes ranged from 9% to 78%. 46,47 In a case series of 11 patients with average follow-up of 18 months,
Giufre et al. reported only one MRC 4 result, notably in a 15-year-old. The remainder of the patients
ranged in age from 18 to 59 years, and only three of these reached MRC 3 extension. 46 However, 7 of the
11 no longer required an ankle-foot orthotic. In contrast, Ferris et al. reported seven of nine patients
achieving MRC 4 ankle extension by 8 to 26 months postoperatively, with an average follow-up of
30.8 months. 47 Patient age, time from injury, and length of follow-up likely contribute to the discrepancy
in outcomes; more studies are necessary before this transfer comes into common use.
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Postoperative Care
Postoperative care is important to obtaining successful outcomes after nerve transfer. The surgical
dressing frequently includes a splint or bulky soft dressing that is removed at postoperative day 2 or 3.
Patients begin working with a therapist who is knowledgeable about motor retraining ideally
preoperatively and then beginning at 3 to 4 weeks postoperatively to begin contractions of donor nerve
muscles. For sensory transfers, sensory input to the newly reinnervated region is critical for cortical
relearning. Cortical remapping is essential for successful outcomes in both motor and sensory nerve
transfers.
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Questions
1. A 12-year-old boy presents after falling out of a tree with a right radial nerve avulsion injury
proximal to the elbow. The patient is otherwise healthy, is right hand dominant, and enjoys sports
and playing the piano. Following an initial washout, the patient returns for definitive reconstruction
3 weeks later. What procedure will give him the best independent finger function?
a. Sural nerve grafting to the radial nerve
b. FCR to extensor digitorum communis tendon transfer
c. FDS III to extensor digitorum communis III, IV, and V and FDS IV to extensor indicis pollicis
tendon transfer
d. Median branch to FCR nerve transfer to posterior interosseous nerve
2. A 32-year-old man presents 6 months after a motorcycle accident. He complains of being unable to
button his shirt, generalized hand weakness, and weak elbow flexion. An electromyography (EMG)
is performed and shows normal motor units in the deltoid and biceps, and there are fibrillations and
motor unit potentials in the FCU and the first dorsal interosseous. What intervention will best
improve his hand function?
a. Transfer of the anterior interosseous branch to pronator quadratus end-to-end to the ulnar
motor branch
b. Transfer of the anterior interosseous branch to pronator quadratus end-to-side (supercharge) to
the ulnar motor branch
c. End-to-end Oberlin transfer of the ulnar fascicle to FCU to the musculocutaneous branch to
biceps
d. Continued observation
3. Twelve months after a knee dislocation injury in a basketball game, a 67-year-old man seeks care
for his foot drop. He has reduced sensation along the lateral calf and no anterior tibialis function.
What is the most appropriate intervention?
a. Posterior tibial tendon transfer to the anterior tibialis tendon
b. Superficial peroneal nerve decompression
c. Transfer of the tibial branch to flexor hallucis longus to the deep peroneal branch to tibialis
anterior
d. Transfer of the femoral branch to vastus medialis to the deep peroneal branch to tibialis
anterior
4. A 3-month-old boy presents with a left flail arm and history of shoulder dystocia. At birth, he had
a left Horner syndrome that has improved significantly. On examination he has a complete flail arm.
Which of the following is correct?
a. Excision of the neuroma and nerve root grafting will likely result in near normal function.
b. The child should be reassessed at 9 months of age with the cookie test before determining if an
intervention is necessary.
c. Transfer of the spinal accessory nerve to the suprascapular, intercostal transfer to
musculocutaneous, and contralateral C7 transfer for posterior cord will result in the best
outcomes.
d. Transfer of the spinal accessory nerve to the suprascapular, Oberlin transfer and radial branch
to triceps to axillary nerve will result in the best outcomes.
5. A 15-year-old boy presents for evaluation of facial palsy 10 months after resection of a vascular
malformation in the brainstem. The patient’s facial movement has been unchanged since surgery. On
examination, the patient has unilateral complete facial paralysis, and EMG evaluation show no
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evidence of motor unit potentials on that side of the face. What is the best technique to reconstruct
dynamic smile in this patient?
a. Segmental sural nerve graft within the ipsilateral buccal branch of the facial nerve
b. Ipsilateral masseteric nerve transfer to the buccal branch
c. Cross-facial sural nerve graft from the contralateral buccal branch to the affected buccal
branch
d. Free functional muscle transfer to the affected face with neurotization via a cross-facial nerve
graft
1. Answer: d. In this scenario, the proximal stump of the radial nerve is not available for grafting
because it is avulsed. Tendon transfers will result in adequate finger extension, but independent
motion will be impossible. The nerve transfer to the PIN will allow for independent finger extension.
2. Answer: b. The patient’s complaint and EMG are consistent with a pan-plexus injury. However,
the presence of motor unit potentials indicates that there is still continuity in the plexus, as is
common in traction injuries associated with motorcycle accidents. The generalized hand weakness
and weak pinch is indicative of intrinsic loss. Transfer of the anterior interosseous branch to pronator
quadratus to the ulnar motor branch has the greatest likelihood of improving hand function given
that the injury is quite proximal. As there is still continuity, an end-to-side transfer is most
appropriate.
3. Answer: a. This patient has a foot drop from an injury to the common peroneal from a knee
dislocation. At 12 months after injury and given his age, the best outcome is likely with tendon
transfer. Although common peroneal decompression may improve recovery, especially sensory
regeneration, the likelihood of regeneration in an older patient that long after injury is very low.
4. Answer: c. This infant likely has a complete avulsion injury of C5-T1, and thus there are likely no
nerve roots available proximally for grafting. Additionally in the scenario of a flail arm and Horner
syndrome, it is recommended that surgery be done prior to 6 months of age. Extraplexal transfers are
likely the best option, bearing in mind what proximal donors are available. The Oberlin transfer and
triceps to axillary transfer can only be done when C7, C8, and T1 are intact.
5. Answer: b. This patient is 10 months out from injury with no clinical or electrodiagnostic evidence
of potential for motor recovery. Given the time from injury, the patient’s native mimetic musculature
is still amenable to reinnervation; therefore free functional muscle transfer is not required. Cross-
facial nerve grafting would prolong time to reinnervation, potentially precluding reinnervation
within the critical window. A proximal nerve stump is not available; therefore segmental grafting is
not possible. Direct transfer of the masseteric nerve to the affected buccal branch provides the most
rapid and robust reinnervation for smile.
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References
Gohritz, A, Dellon, LA, Guggenheim, M, et al. Otfrid Foerster (1873–1941)—self-taught neurosurgeon and innovator of reconstructive
peripheral nerve surgery. J Reconstr Microsurg. 2013;29(1):33-43.
Gordon, T, Yang, JF, Ayer, K, et al. Recovery potential of muscle after partial denervation: a comparison between rats and humans. Brain Res
Bull. 1993;30(3-4):477-482.
Schreiber, JJ, Byun, DJ, Khair, MM, et al. Optimal axon counts for brachial plexus nerve transfers to restore elbow flexion. Plast Reconstr Surg.
2015;135(1):135e-141e.
Terzis, JK, Wang, W, Zhao, Y. Effect of axonal load on the functional and aesthetic outcomes of the cross-facial nerve graft procedure for
facial reanimation. Plast Reconstr Surg. 2009;124(5):1499-1512.
Leland, HA, Azadgoli, B, Gould, DJ, Seruya, M. Investigation into the optimal number of intercostal nerve transfers for musculocutaneous
nerve reinnervation: a systematic review. Hand (NY). 2017;13(6):621-626. doi:10.1177/1558944717744280.
Viterbo, F, Amr, AH, Stipp, EJ, Reis, FJ. End-to-side neurorrhaphy: past, present, and future. Plast Reconstr Surg. 2009;124(6 suppl):e351-358.
Cederna, PS, Kalliainen, LK, Urbanchek, MG, et al. “Donor” muscle structure and function after end-to-side neurorrhaphy. Plast Reconstr
Surg. 2001;107(3):789-796.
Slattery, WH, Cassis, AM, Wilkinson, EP, et al. Side-to-end hypoglossal to facial anastomosis with transposition of the intratemporal facial
nerve. Otol Neurotol. 2014;35(3):509-513.
Farber, SJ, Glaus, SW, Moore, AM, Hunter, DA, Mackinnon, SE, Johnson, PJ. Supercharge nerve transfer to enhance motor recovery: a
laboratory study. J Hand Surg Am. 2013;38(3):466-477.
Davidge, KM, Yee, A, Moore, AM, Mackinnon, SE. The supercharge end-to-side anterior interosseous-to-ulnar motor nerve transfer for
restoring intrinsic function: clinical experience. Plast Reconstr Surg. 2015;136(3):344e-352e.The supercharge technique can be used in scenarios
wherein native regeneration is anticipated or some quantity of native axons remain intact. This article reviews the efficacy of supercharge transfers of
the AIN branch to pronator quadratus to the ulnar motor branch in injuries ranging from sharp proximal transection to neuritis and chronic
radiculopathies. The authors found that there was no donor deficit and over 70% of patients achieved MRC over 3 versus 15% preoperatively. The
authors carefully parse out the contributions of the supercharge by assessing the time course of recovery versus what would be expected based on the
level of the lesion.
Wan, H, Zhang, L, Li, D, et al. Hypoglossal-facial nerve “side”-to-side neurorrhaphy for persistent incomplete facial palsy. J Neurosurg.
2014;120(1):263-272.
Dellon, AL, Ferreira, MC, Williams, EH, Rosson, GD. Which end is up? Terminology for terminolateral (end-to-side) nerve repair: a review. J
Reconstr Microsurg. 2010;26(5):295-301.
Terzis, JK, Tzafetta, K. The “babysitter” procedure: minihypoglossal to facial nerve transfer and cross-facial nerve grafting. Plast Reconstr
Surg. 2009;123(3):865-876.
Bain, JR, Veltri, KL, Chamberlain, D, Fahnestock, M. Improved functional recovery of denervated skeletal muscle after temporary sensory
nerve innervation. Neuroscience. 2001;103(2):503-510.
Zhang, F, Lineaweaver, WC, Ustüner, T, et al. Comparison of muscle mass preservation in denervated muscle and transplanted muscle flaps
after motor and sensory reinnervation and neurotization. Plast Reconstr Surg. 1997;99(3):803-814.
Placheta, E, Wood, MD, Lafontaine, C, et al. Enhancement of facial nerve motoneuron regeneration through cross-face nerve grafts by adding
end-to-side sensory axons. Plast Reconstr Surg. 2015;135(2):460-471.
Snyder-Warwick, AK, Fattah, AY, et al. The degree of facial movement following microvascular muscle transfer in pediatric facial
reanimation depends on donor motor nerve axonal density. Plast Reconstr Surg. 2015;135(2):370e-381e.
Coombs, CJ, Ek, EW, Wu, T, et al. Masseteric-facial nerve coaptation–an alternative technique for facial nerve reinnervation. J Plast Reconstr
Aesthet Surg. 2009;62(12):1580-1588.The masseteric nerve provides a reliable and strong neurotization source for free functional gracilis transfer to
the face for dynamic smile reconstruction. In this study, histomorphometric data obtained from masseteric nerve biopsies at the time of gracilis transfer
showed an average of 1542 myelinated axons. Based on these data, direct masseteric to buccal branch or facial nerve trunk transfers for facial
reanimation were performed in three patients. Outcomes demonstrated improved symmetry at rest and with animation, as well as the possibility for
spontaneous expression. No donor morbidity resulted from masseteric nerve use.
Borschel, GH, Kawamura, DH, Kasukurthi, R, et al. The motor nerve to the masseter muscle: an anatomic and histomorphometric study to
facilitate its use in facial reanimation. J Reconstr Aesthet Surg. 2012;65(3):363-366.This article describes the anatomic landmarks for location of the
masseteric nerve. In this cadaver study, the masseteric nerve was consistently located 3.16 cm anterior to the tragus, 1.08 cm inferior to the inferior
border of the zygomatic arch, and 1.48 cm deep to the SMAS. The masseteric nerve makes a 50-degree angle with the zygomatic arch and travels
1.33 cm inferior to the arch before branching. The masseteric nerve has an average of 2775 myelinated fibers.
Mundschenk, MB, Sachanandani, NS, Borschel, GH, et al. Motor nerve to the masseter: a pediatric anatomic study and the “3:1 rule”Motor
nerve to the masseter: a pediatric anatomic study and the “3:1 rule”Motor nerve to the masseter: a pediatric anatomic study and the “3:1
rule”. J Plast Reconstr Aesthet Surg. 2018;71(1):54-56.
Manktelow, RT, Tomat, LR, Zuker, RM, Chang, M. Smile reconstruction in adults with free muscle transfer innervated by the masseter motor
nerve: effectiveness and cerebral adaptation. Plast Reconstr Surg. 2006;118(4):885-899.
Chen, G, Wang, W, Wang, W, et al. Symmetry restoration at rest after masseter-to-facial nerve transfer: is it as efficient as smile reanimation?
Plast Reconstr Surg. 2017;140(4):793-801.
Mahan, MA, Sivakumar, W, Weingarten, D, Brown, JM. Deep temporal nerve transfer for facial reanimation: anatomic dissections and
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surgical case report. Oper Neurosurgery (Hagerstown, Md). 2017.
Rodriguez-Lorenzo, A, Jensson, D, Weninger, WJ, Schmid, M, Meng, S, Tzou, CH. Platysma motor nerve transfer for restoring marginal
mandibular nerve function. Plast Reconstr Surg Glob Open. 2016;4(12):e1164.
Terzis, JK, Dryer, MM, Bodner, BI. Corneal neurotization: a novel solution to neurotrophic keratopathy. Plast Reconstr Surg. 2009;123(1):112-
120.
Elbaz, U, Bains, R, Zuker, RM, et al. Restoration of corneal sensation with regional nerve transfers and nerve grafts: a new approach to a
difficult problem. JAMA Ophthalmol. 2014;132(11):1289-1295.Corneal neurotization is a fascinating application of nerve transfers for restoring
corneal sensation and preventing blindness resulting from corneal ulcerations and or perforations. This study reviews the outcomes from four corneal
neurotization procedures secondary to acquired corneal anesthesia in children. All four patients achieved meaningful corneal sensation using
supratrochlear donor nerves and a nerve graft to directly neurotize the cornea.
Fung, SSM, Catapano, J, Elbaz, U, et al. In vivo confocal microscopy reveals corneal reinnervation after treatment of neurotrophic
keratopathy with corneal neurotization. Cornea. 2018;37(1):109-112.
Koshima, I, Narushima, M, Mihara, M, et al. Cross-face nerve transfer for established trigeminal branch II palsy. Ann Plast Surg.
2009;63(6):621-623.
Goubier, JN, Teboul, F. Rhomboid nerve transfer to the suprascapular nerve for shoulder reanimation in brachial plexus palsy: a clinical
report. Hand Surg Rehabil. 2016;35(5):363-366.
Koshy, JC, Agrawal, NA, Seruya, M. Nerve transfer versus interpositional nerve graft reconstruction for posttraumatic, isolated axillary
nerve injuries: a systematic review. Plast Reconstr Surg. 2017;140(5):953-960.
Oberlin, C, Béal, D, Leechavengvongs, S, et al. Nerve transfer to biceps muscle using a part of ulnar nerve for C5-C6 avulsion of the brachial
plexus: anatomical study and report of four cases. J Hand Surg Am. 1994;19(2):232-237.
Mackinnon, SE, Novak, CB, Myckatyn, TM, Tung, TH. Results of reinnervation of the biceps and brachialis muscles with a double fascicular
transfer for elbow flexion. J Hand Surg Am. 2005;30(5):978-985.
Carlsen, BT, Kircher, MF, Spinner, RJ, et al. Comparison of single versus double nerve transfers for elbow flexion after brachial plexus injury.
Plast Reconstr Surg. 2011;127(1):269-276.
García-López, A, Navarro, R, Martinez, F, Rojas, A. Nerve transfers from branches to the flexor carpi radialis and pronator teres to
reconstruct the radial nerve. J Hand Surg Am. 2014;39(1):50-56.
Flores, LP. Comparative study of nerve grafting versus distal nerve transfer for treatment of proximal injuries of the ulnar nerve. J Reconstr
Microsurg. 2015;31(9):647-653.
Kovachevich, R, Kircher, MF, Wood, CM, et al. Complications of intercostal nerve transfer for brachial plexus reconstruction. J Hand Surg
Am. 2010;35(12):1995-2000.
Zheng, MX, Xu, WD, Qiu, YQ, et al. Phrenic nerve transfer for elbow flexion and intercostal nerve transfer for elbow extension. J Hand Surg
Am. 2010;35(8):1304-1309.
Tse, R, Marcus, JR, Curtis, CG, et al. Suprascapular nerve reconstruction in obstetrical brachial plexus palsy: spinal accessory nerve transfer
versus C5 root grafting. Plast Reconstr Surg. 2011;127(6):2391-2396.
Chang, KWC, Wilson, TJ, Popadich, M, et al. Oberlin transfer compared with nerve grafting for improving early supination in neonatal
brachial plexus palsy. J Neurosurg Pediatr. 2018;21(2):178-184.
Ladak, A, Morhart, M, O’Grady, K, et al. Distal nerve transfers are effective in treating patients with upper trunk obstetrical brachial plexus
injuries: an early experience. Plast Reconstr Surg. 2013;132(6):985e-992e.
O’Grady, KM, Power, HA, Olson, JL, et al. Comparing the efficacy of triple nerve transfers with nerve graft reconstruction in upper trunk
obstetric brachial plexus injury. Plast Reconstr Surg. 2017;140(4):747-756.Reconstruction of birth related brachial plexus palsies has evolved
significantly over the last several decades. The incorporation of distal nerve transfers into the armamentarium for treating these injuries brings several
advantages: reduced operative time, reduced hospital stay, and equivalent to improved outcomes. This article reviews an approach to upper trunk
injuries utilizing three different nerve transfers: spinal accessory to suprascapular, radial branch to triceps transfer to axillary, and ulnar branch to
FCU transfer to musculocutaneous.
Anand, P, Birch, R. Restoration of sensory function and lack of long-term chronic pain syndromes after brachial plexus injury in human
neonates. Brain. 2002;125(Pt 1):
 113-122.
Tung, TH, Chao, A, Moore, AM. Obturator nerve transfer for femoral nerve reconstruction: anatomic study and clinical application. Plast
Reconstr Surg. 2012;130(5):1066-1074.
Moore, AM, Krauss, EM, Parikh, RP, et al. Femoral nerve transfers for restoring tibial nerve function: an anatomical study and clinical
correlation: a report of 2 cases. J Neurosurg. 2018;129(4):1024-1033.
Koshima, I, Nanba, Y, Tsutsui, T, Takahashi, Y. Deep peroneal nerve transfer for established plantar sensory loss. J Reconstr Microsurg.
2003;19(7):451-454.
Giuffre, JL, Bishop, AT, Spinner, RJ, et al. Partial tibial nerve transfer to the tibialis anterior motor branch to treat peroneal nerve injury after
knee trauma. Clin Orthop Relat Res. 2012;470(3):779-790.
Ferris, S, Maciburko, SJ. Partial tibial nerve transfer to tibialis anterior for traumatic peroneal nerve palsy. Microsurgery. 2017;37(6):596-
602.Lower extremity nerve transfers are emerging techniques. Foot drop from common peroneal palsy is debilitating, and outcomes for nerve transfers
addressing this problem have had previously relatively poor results in adults. In this prospective series, tibial donors, generally branches to flexor
digitorum longus, were used for transfers to tibialis anterior. The series reports 7 of 9 patients achieving MRC better than 4.
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C H A P T E R 7 2
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Management of Brachial Plexus Injuries
Frank Fang and Kevin C. Chung
Key Points
Brachial plexus injuries are permanently disabling. Even the best results from surgical interventions
are only partially restorative of the original functional capacity.
Surgery is undertaken for closed injuries when physical examination and diagnostic modalities show
a plateau or absence of functional recovery (ideally 3–5 months post trauma).
Surgical interventions can be organized into three broad categories: proximal exploration and
reconstruction, distal nerve transfers, and biomechanical restorations.
Adult and infant brachial plexus injuries are different pathologic entities with varying strategies of
surgical intervention.
There are multiple prevailing philosophies upon management of brachial plexus injuries; rigorous
outcomes studies to produce evidence-based conclusions upon best practices are still pending.
Brachial plexus injuries occur in two general categories: adult trauma and obstetric birth trauma. Surgical
intervention for these injuries can be categorized into three basic groups—proximal explorations with
nerve transfers or nerve grafting, distal (close target) nerve transfers, and biomechanical restorations
(tendon transfers and functioning free muscle transplantations). Differing opinions exist regarding the
merits and drawbacks of these three groups and their applications. Owing to the atrophy and fibrosis of
the neuromuscular junctions that occur approximately 12 to 18 months after denervation, the time
elapsed since trauma is the most important factor to consider when determining which surgical
intervention is appropriate. The treatment course for these injuries can span a lifetime, and the technical
difficulty of many of the involved procedures is high. Permanent functional disability is certain. The
severity of the life-changing impairment depends upon the magnitude and foci of the injury. For clarity
of presentation within the scope of this chapter, we will first discuss adult brachial plexus followed by
coverage of obstetric brachial plexus palsy.
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Epidemiology
The mechanism of injury for adult brachial plexus trauma varies by region. The energy of injury differs
by the mechanism of injury. For instance, lower-speed moped-associated injuries (accounting for >90% of
brachial plexus injuries in regions such as Taiwan, Southeast Asia, and India) generally have a lower
energy than high-speed motor vehicle or motorcycle accidents (approximately 84% of cases in Europe
and North America). 1,2 Lower-energy mechanisms tend to produce postganglionic nerve ruptures
(breakages within the substance of the peripheral nerve, distal to the dorsal root ganglion) as compared
with higher-energy mechanisms which tend to produce more preganglionic root avulsions (tearing of the
rootlets of the peripheral nerve directly from the spinal cord, proximal to the dorsal root ganglion).
Gunshot wounds are typically seen in war zones and also commonly in the United States (17% of brachial
plexus injuries), and they can be subdivided into high-velocity (military rifles, hunting rifles, shotguns)
versus lower-velocity (handgun) trauma with implications upon prognosis and management. 3–5 Lastly,
sharp lacerating injuries of the brachial plexus, such as with knife attacks, account for approximately 10%
of presenting cases at a trauma center in the U.S. Despite regional variations in the mechanism of injury,
adult brachial plexus trauma mostly affects young males worldwide (>90%). 1
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Anatomy
The brachial plexus is a confluence of interconnecting nerves that reside in between where the spinal
nerves emanate from the spinal cord and ultimately course into the shoulder girdle and upper extremity
muscles. Each spinal nerve is formed from rootlets of the ventral and dorsal roots that arise from the
spinal cord and unite as the spinal nerve before exiting the dural sac of the spinal cord and running along
a groove within the bony vertebra between the anterior and posterior tubercles of the transverse
processes of C5 to T1. The dorsal root, which contributes sensory nerves only, is thicker and more
resistant to avulsion forces. To note, anatomical variations exist where a prefixed or postfixed brachial
plexus has substantive contribution to the innervation of the upper or lower trunk from a C4 or T2 spinal
nerve, respectively. These variants may cause a less severe injury deficit than expected for a given injury.
The dorsal root ganglion is generally positioned just posterior and medial to the vertebral artery, and it is
thus contained within the vertebral bony structure and not visible upon surgical exposure, unless the
spinal nerve has been avulsed distally 6 (Figure 72.1). The spinal nerves then coalesce into the upper (C5
and C6), middle (C7), and lower (C8 and T1) trunks which are contained between the anterior and middle
scalene muscles. Each trunk then splits into anterior and posterior divisions within the area deep to the
clavicle. To note, the upper trunk’s anterior and posterior divisions are also positioned very close to the
branch point of the suprascapular nerve, to give the appearance of a trifurcation of nerves near that point.
Also notable, the posterior division of lower trunk is quite small. After the divisions emerge inferior to
the clavicle, they become the lateral, posterior, and medial cords in the area deep to the pectoralis minor
(that inserts upon the useful bony landmark of the coracoid process). At the cord level, the axillary artery
is sandwiched between the three cords. From the cords arise the branches that innervate the shoulder
girdle and distal upper extremity. The axillary and radial nerve are separable at the region of the
posterior cord deep to the lateral border of the pectoralis minor. The musculocutaneous nerve can be
located at the proximal arm in the plane between the coracobrachialis and biceps brachialis. The median
and ulnar nerves are most easily found in the mid-distal arm deep to the brachial veins as they wrap
around the brachial artery (Figure 72.2).
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FIGURE 72.1 Spinal nerve and associated anatomy.
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FIGURE 72.2 Brachial plexus anatomy.
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Anatomic Classification of Brachial Plexus Injury
There are multiple systems of anatomic classification of brachial plexus injury that have been popularized
by major contributors to surgical advances in brachial plexus injury treatment. We will highlight three
classification systems: Terzis’ three-level system of root, supraclavicular postganglionic, and
infraclavicular injuries
7 ; the Alnot classification of preganglionic root, postganglionic root,
supraclavicular and retroclavicular, and infraclavicular injuries 8 ; and Chuang’s level 1 to 4 classification
separates injuries into preganglionic (root avulsion), postganglionic, pre- and retroclavicular, and
infraclavicular injuries. 9 All three classifications consider the important factors of surgical decision-
making: whether spinal root avulsion has occurred, the location of postganglionic rupture, and the
clavicle as an operative landmark and barrier (Table 72.1).
TABLE 72.1
Brachial Plexus Injury Classification Systems
Alnot
Terzis
Chuang
Preganglionic root
Preganglionic supraclavicular
Preganglionic root (level 1)
Postganglionic root
Postganglionic supraclavicular
Postganglionic spinal nerve (level 2)
Supra-/retroclavicular
–
Pre-/retroclavicular (level 3)
Infraclavicular
Infraclavicular
Infraclavicular (level 4)
Although any combination of spinal nerve rupture or avulsion is theoretically possible with adult trauma,
some common injury patterns for closed brachial plexus injury are consistent worldwide with some
variability in frequency 3 :
C5-C6: 15%
C5-C7: 20%–35%
C8-T1: 10%
C5-T1: 50%–70%
The higher frequency of upper trunk pathology with closed injuries may be related to the reflexive
terminal position established by a person when encountering impending collision to the head and neck
region. The blunt force at the shoulder region in combination with neck flexion to the contralateral side
results in sudden caudal force trajectory upon the arm with the greatest energy directed upon the upper
and middle trunks (Figure 72.2). Cephalic traction upon the arm with consequent lower trunk injury is
much more rarely encountered, and this occurrence can often be attributed to a loss of consciousness
prior to the time point of impact.
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Nerve Injury Classification
Classification systems of nerve injury delineate the range of injury from axonotmesis to neurotmesis with
progressive involvement of endoneurium, perineurium, and epineurium as injury severity increases 10
(Figure 72.3). Most closed injuries of the brachial plexus are actually mixed in nature (Mackinnon’s sixth
degree injury). Thus, during the initial period of time (typically at least 3–6 months post trauma), the
demyelinated and defunctionalized nerve is in a period where some of the injured elements that meet
criteria for Mackinnon’s first through third degrees of nerve injury severity will recover spontaneously.
Allowing time for the nerve to recover spontaneously is akin to waiting for tissue demarcation as is done
after thermal injury to the skin. However, with nerve trauma, it is unclear whether the final severity of
the injury is determined by the damage of the initial trauma or if favorable and harmful factors during
the initial period of time after trauma can affect the evolution of the final severity of the injury (such as
with burn injury).
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FIGURE 72.3 Classification of nerve injuries. A. Uninjured nerve consists of myelinated axons, surrounded by endoneurium,
grouped into fascicles surrounded by perineum. The outer layer of the nerve is epineurium. In a first-degree injury, the axons
are only demyelinated, whereas in a second-degree injury, the axons are injured and undergo degeneration. A third-degree
injury includes damage to the axons, myelin, and endoneurium. A fourth-degree injury is a complete scar block that prevents
any regeneration. A fifth-degree injury is a division of the nerve. B. The pattern of injury may vary from fascicle to fascicle along
the nerve. This mixed pattern of injury is considered a sixth-degree injury.
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