Operative Technique in Plastic Surgery – Kevin C.Chung

characterized by contralateral bulging and ipsilateral forehead recession.
■ Metopic synostosis leads to trigonocephaly, which is characterized by a
narrow, triangle-shaped forehead, superolateral orbital depression, and
hypotelorism.
■ Bicoronal synostosis leads to brachycephaly, which is characterized by
decreased AP diameter and increased biparietal width and height.
■ Multisuture synostosis typically involving the coronal, lambdoid, and
metopic sutures can cause kleeblattschädel or cloverleaf deformity.
■ Craniosynostosis may also have neurologic, psychiatric, and cognitive
implications.3
■ There is increasing evidence that patients with craniosynostosis have a high
incidence of elevated intracranial pressure (ICP).4–6
■ Earlier surgical intervention in craniosynostosis has been shown to be
associated with improved neurocognitive outcomes7 and may be mediated by
preventing ICP elevation.6
FIG 2 • 3D CT scans of the same female infant with
right unicoronal synostosis.
■ Hydrocephalus is more common in patients with syndromic craniosynostosis.
Within the syndromic cohort, Crouzon syndrome patients tend to have the

highest incidence of hydrocephalus.
■ Craniosynostosis is associated with a higher incidence of speech/language,
behavioral, and neurocognitive developmental delays.3,8
PATIENT HISTORY AND PHYSICAL FINDINGS
■ Patients will typically present with a history of abnormal head shape during
infancy (FIG 1A,B).
■ Physical exam is the mainstay of diagnosis for single-suture nonsyndromic
craniosynostosis.
■ On exam, patients with single-suture craniosynostosis will have the
characteristic skull shapes as described in natural history.
■ Physical exam should also focus on delineating underlying syndromic
etiology, which includes assessing for abnormal facial features and limb
anomalies.
■ Clinical symptoms like headache and visual changes, with papilledema on
fundoscopic examination, are signs of increased ICP, a possible sequela of
craniosynostosis.
IMAGING
■ Although physical exam is often sufficient for diagnosis, imaging with either
plain radiographs or 3D computed tomography may be required in borderline
or complex cases in order to accurately characterize the anatomy and aid in
preoperative planning.
■ Plain radiographs may be useful if the pretest probability of craniosynostosis
(based on history and physical exam) is low.
■ 3D computed tomography is useful for accurately identifying the suture(s)
involved and characterizing the bony deformity but can also be used to
evaluate the brain parenchyma and other soft tissues (FIG 2).
■ In infants with suspected syndromic craniosynostosis, genetic testing for the
most common genes (FGFR and TWIST) can be performed.
■ Detection of optic nerve pathology and elevated ICP may also be possible
through the use of visual evoked potential (VEP) testing or retinal imaging
with optical coherence tomography (OCT).9,10
DIFFERENTIAL DIAGNOSIS
■ Positional plagiocephaly
■ Congenital torticollis

■ Craniosynostosis
SURGICAL MANAGEMENT
■ Craniosynostosis is managed surgically through a variety of different
techniques.
■ The goals of surgery are twofold:
■ Functional: to prevent intracranial hypertension from damaging the
developing brain
■ Aesthetic: to normalize the patient’s appearance
FIG 1 • Female infant with right unicoronal synostosis at
1.5 months of age.
■ The optimal timing of surgical intervention is an area of controversy.
■ Operating earlier may be associated with improved neurocognitive outcomes
but has increased perioperative risks as well as an increased risk for needing
additional surgery later in childhood.
■ Operating later may be associated with worse neurocognitive outcomes but
has reduced perioperative risks and better long-term aesthetic outcomes.
■ Traditionally, strip suturectomy was the mainstay of treatment, but current
approaches include posterior calvarial remodeling (CVR), fronto-orbital
advancement (FOA), posterior vault distraction osteogenesis (PVDO), and,
most recently, fronto-orbital distraction osteogenesis.

■ Distraction osteogenesis is the process through which slow and gradual
expansion of osteotomized bone leads to new endogenous bone formation.
■ It has been used to lengthen mandibles as well as expand the posterior and
anterior cranial vault.
■ It reduces the need for autologous bone grafts and aids in the expansion of
the overlying soft tissues.11
■ Compared to traditional cranial vault remodeling, distraction osteogenesis has
multiple benefits, including the following:
■ Perioperative: less invasive surgery, shorter surgical time, decreased blood
loss, shorter ICU and hospital length of stay12
■ Physiologic: preserved bone vascularity, improved quality of bony
regenerate, no implantation of permanent hardware in a growing skull
■ Minimizes dead space within the head, thereby minimizing the risk of a deep
space infection
■ Outcomes: possible to make postoperative adjustments (depending on type of
distractor utilized), increased magnitude of movement, increased volume
expansion, gradual soft tissue envelope expansion, and decreased relapse13,14
Preoperative Planning
■ 3D head CT scans should be reviewed.
■ The plastic surgeon and neurosurgeon should communicate regarding the
surgical approach.
■ The surgeon should be familiar with cranial distraction devices.
Positioning
■ The patient is placed supine on the operating room table.
■ General anesthesia is induced, and the head and neck are shaved, prepped, and
draped in a sterile fashion.
■ A curvilinear coronal incision is made with a marking pen and infiltrated with
local anesthesia containing epinephrine.
Approach
■ For both metopic and unicoronal synostosis, the approach for fronto-orbital
distraction osteogenesis is the same as the approach utilized for conventional
FOA.
■ The curvilinear coronal incision is opened to the subgaleal plane, and

subperiosteal elevation of the anterior cranial and periorbital soft tissues is
performed. The authors prefer a subperiosteal approach to the anterior cranial
vault and base, but there is a paucity of data comparing this approach to the
subgaleal approach.
T E C H N I Q U E S
■ Unicoronal Synostosis Fronto-Orbital Distraction
Osteogenesis
Bone Cuts
■ Perform a unilateral coronal suturectomy, 2 to 4 mm wide, with an ultrasonic
scalpel (TECH FIG 1A,B).
■ Place bur holes along the lines of anticipated osteotomies, making sure to
place one bur hole at the base of the fused coronal suture in the pterional
region, a so-called pterional window through which osteotomies of the
greater wing of the sphenoid and the lateral orbital wall will later be made.
■ Limit dural dissection to directly underlying the planned osteotomy, thus
keeping the majority of the dura attached to the overlying frontal bone.
■ Use the ultrasonic scalpel to perform all cuts similar to a typical FOA. Bone
cuts include (TECH FIG 1B–D)
■ A vertical “perforating,” or incomplete, osteotomy from the contralateral
orbit to the anterior fontanelle at the inflection point of the deformity
■ Inferior orbital cuts along the orbital roof with special care taken to retract
the brain and globe
■ Radial osteotomies along the orbital roof to unfurl the horizontally short
orbit
■ Careful osteotomies of the greater wing of the sphenoid, lateral orbital rim,
and the lateral orbital wall.
• Use malleable retractors to provide access through the “pterional
window.”
• One malleable retracts the frontal lobe, another the temporal lobe, and a
third the soft tissues of the orbit.
■ Extend cuts to the medial third of the contralateral orbit.

■ Keep the bandeau en bloc with the frontal bone.
TECH FIG 1 • A. Osteotomies for unicoronal
synostosis correction using distraction osteogenesis.
B. Radial orbital roof osteotomies and vertical
perforating osteotomies. C. Unicoronal suturectomy.
D. Frontal bone radial osteotomies.
■ Device Application
■ Rigidly fixate a uniplanar cranial vault distractor to the low to midparietal
region in the forehead.
■ Confirm an anterior and slightly inferior vector for orbital rim
overcorrection.

■ Place Gelfoam under the fixation screws to avoid dural injury during
distraction.
■ Activate the distractor to ensure completeness of the osteotomy.
■ Return distractor to its original position.
■ Place a drain under the forehead scalp flap.
■ Perform a layered scalp closure.
■ Metopic Synostosis Fronto-Orbital Distraction
Osteogenesis
Bone Cuts
■ Following subperiosteal elevation of the forehead soft tissues performed
with conventional FOA, perform a narrow (5 mm) metopic suturectomy with
a Hudson brace and ultrasonic scalpel under direct visualization (TECH FIG
2A).
■ Make the pterional windows bilaterally, which permits limited dissection of
the frontal and temporal lobes under the osteotomy sites.
■ Dissect the dura directly underlying the osteotomy, keeping a portion of the
dura attached to the overlying frontal bone.
■ Use the ultrasonic scalpel to make all cuts typical of a conventional FOAR,
including coronally oriented osteotomies posterior to the coronal sutures at
the transition between “normal” occiput and “abnormal” forehead (TECH
FIG 2B–E).
■ Do not separate the frontal bandeau from the frontal bone.
■ Make the sphenoid wing and orbital roof osteotomies through the pterional
window.
■ Make additional radial osteotomies along the orbital roof and frontal bones
to allow for gradual remodeling and flexing of bone during the activation
phase of distraction.
■ Fill in bone gaps, as necessary, with particulate bone grafts.
Rigid Fixation and Device Application
■ Place the dura on stretch in the region of the metopic suture and place an
interpositional bone graft (approximately 2 × 1 cm) at the nasofrontal
junction.

■ Fixate bone graft to the nasal bones and bilateral frontal bones in a slightly
advanced position.
■ No additional advancement of the nasofrontal region is meant to occur
during distraction, and thus, the nasofrontal region should be placed in its
final anteroposterior position.
TECH FIG 2 • A. Osteotomies for metopic synostosis
correction using distraction osteogenesis. Markings for
the site of metopic suturectomy (B) and pterional
window (C). D,E. Coronally oriented osteotomies and
an interpositional bone graft are placed.
■ Rigidly fixate the uniplanar cranial vault distractors to the midparietal region

in the forehead with an anteroposterior vector, ensuring translocation of the
forehead and orbital rims to their proper location.
■ Importantly, the vector of distraction should not narrow the forehead;
instead, distractors should be parallel to one another in the sagittal plane
(TECH FIG 3).
■ Place Gelfoam under the fixation screws to avoid dural injury during
distraction.
■ Activate the distractor to ensure completeness of osteotomy.
■ Return the distractor to its original position.
■ Fill in bone gaps, as necessary, with particulate bone grafts.
■ Place a drain under the forehead scalp flap.
■ Perform a layered scalp closure.
TECH FIG 3 • When fixating distractors for correction
of metopic synostosis, confirm that the vector of
distraction does not narrow the forehead. Distractors
should be parallel to one another in the sagittal plane,
as seen in this bird’s-eye view of a postoperative 3D
CT scan.

PEARLS AND PITFALLS
Ultrasonic
scalpel
■ Perform cuts with an ultrasonic scalpel for increased precision and
safety.
Osteotomy
■ Always activate the distractor prior to closure to ensure completeness
of osteotomies.
Bandeau
■ Unlike traditional FOAR, do not separate the frontal bandeau from the
frontal bone for either metopic or unicoronal fronto-orbital distraction.
Gelfoam
■ Placement of Gelfoam under the fixation screws avoids injury to the
underlying dura during the activation phase of distraction.
Dural
dissection
■ Limit dural dissection to directly underneath the osteotomy, thereby
maintaining vascularity of the bone flaps.
POSTOPERATIVE CARE
■ Start distraction on the second postoperative day at a rate of 1 mm/day.
■ For both metopic and unicoronal synostosis, the end point of activation is a
slight overcorrection of the deformity, as optimal growth of the frontal region
is not likely to occur.
■ The consolidation phase ranges from 8 to 12 weeks.
OUTCOMES
■ Fronto-orbital distraction is in its infancy, and though short-term data exist,
there is a paucity of data relating to long-term outcomes (FIGS 3 and 4).
■ Choi et al.15 first described one-piece FOA with distraction for coronal
craniosynostosis in 2009 and found that compared to the traditional approach,
anterior vault distraction was less invasive and resulted in satisfactory
correction.
■ In 2010, Choi et al.16 demonstrated that anterior vault distraction results in
greater correction of the skull base angulation seen in unicoronal synostosis.
■ Taylor et al. compared a cohort of six unicoronal synostosis patients
undergoing fronto-orbital distraction to a cohort of six unicoronal synostosis
patients undergoing conventional FOAR.12

■ All 12 patients completed therapy without complications and with Whitaker I
scores.
■ The fronto-orbital distraction group had statistically shorter duration of
surgery and length of hospital stay.
■ The conventional FOAR group was significantly more likely to develop
new-onset postoperative strabismus.
■ However, Fearon et al.17 performed a similar comparison between
conventional FOA and fronto-orbital distraction in syndromic craniosynostosis
patients and found that distraction did not have significant advantages in terms
of complication rates, reoperation rates, and anthropometric measurements.
■ Anterior vault distraction has also been described for the treatment of
multisuture craniosynostosis. Taylor et al. described the placement of two
coronal distractors and one sagittal distractor in an effort to expand the cranial
vault while limiting surgical invasiveness.18
■ The nondevascularizing nature of fronto-orbital distraction has been
hypothesized to have a positive impact on growth, but this has yet to be
comprehensively studied.
■ Long-term studies are needed to assess the outcomes of fronto-orbital
distraction vs the outcomes of conventional FOAR.
COMPLICATIONS
■ Dural and brain injury may be masked because bone flaps remain in place.
■ Dural bleeding may be more difficult to control due to the presence of bone
flaps.
■ Incomplete osteotomy
■ Transcutaneous position of distractors predisposes to superficial “pin-site”
infections, which are typically treated with local wound care and antibiotics.
■ Device failure:
■ Screw thread failure
■ Baseplate failure
■ Failure at the interface of bone and hardware
■ External distractor arm failure

FIG 3 • A. Postoperative periorbital aesthetics. B,C. At
age 26 months, 21 months after surgical correction.

FIG 4 • Girl with metopic synostosis. Preoperative
photographs (A–C) and CT scans (D–F) at 8 months of
age. Postoperative photographs (G–I) and 3D CT scans
(J–L) at 25 months of age (17 months postoperatively).

REFERENCES
1. Lee HQ, Hutson JM, Wray AC, et al. Changing epidemiology of
nonsyndromic craniosynostosis and revisiting the risk factors. J Craniofac
Surg. 2012;23(5):1245-1251.
2. Cohen MM. Etiopathogenesis of craniosynostosis. Neurosurg Clin N Am.
1991;2(3):507-513.
3. Becker DB, Petersen JD, Kane AA, et al. Speech, cognitive, and behavioral
outcomes in nonsyndromic craniosynostosis. Plast Reconstr Surg.
2005;116(2):400-407.
4. Gault DT, Renier D, Marchac D, Jones BM. Intracranial pressure and
intracranial volume in children with craniosynostosis. Plast Reconstr Surg.
1992;90(3):377-381.
5. Renier D, Sainte-Rose C, Marchac D, Hirsch JF. Intracranial pressure in
craniostenosis. J Neurosurg. 1982;57(3):370-377.
6. Wall SA, Thomas GPL, Johnson D, et al. The preoperative incidence of raised
intracranial pressure in nonsyndromic sagittal craniosynostosis is
underestimated in the literature. J Neurosurg Pediatr. 2014;14(6):674-681.
7. Hashim PW, Patel A, Yang JF, et al. The effects of whole-vault cranioplasty
versus strip craniectomy on long-term neuropsychological outcomes in sagittal
craniosynostosis. Plast Reconstr Surg. 2014;134(3):491-501.
8. Speltz ML, Kapp-Simon KA, Cunningham M, et al. Single-suture
craniosynostosis: a review of neurobehavioral research and theory. J Pediatr
Psychol. 2004;29(8):651-668.
9. Liasis A, Thompson DA, Hayward R, Nischal KK. Sustained raised
intracranial pressure implicated only by pattern reversal visual evoked
potentials after cranial vault expansion surgery. Pediatr Neurosurg.
2003;39(2):75-80.
10. York DH, Pulliam MW, Rosenfeld JG, Watts C. Relationship between visual
evoked potentials and intracranial pressure. J Neurosurg. 1981;55(6):909-916.
11. McCarthy JG, Stelnicki EJ, Mehrara BJ, Longaker MT. Distraction
osteogenesis of the craniofacial skeleton. Plast Reconstr Surg.
2001;107(7):1812-1827.
12. Tahiri Y, Swanson JW, Taylor JA. Distraction osteogenesis versus
conventional fronto-orbital advancement for the treatment of unilateral coronal
synostosis: a comparison of perioperative morbidity and short-term outcomes.
J Craniofac Surg. 2015;26(6):1904-1908.
13. Swanson JW, Samra F, Bauder A, et al. An algorithm for managing

syndromic craniosynostosis using posterior vault distraction osteogenesis.
Plast Reconstr Surg. 2016;137(5):829e-841e.
14. Derderian CA, Wink JD, McGrath JL, et al. Volumetric changes in cranial
vault expansion: comparison of fronto-orbital advancement and posterior
cranial vault distraction osteogenesis. Plast Reconstr Surg. 2015;135(6):1665-
1672.
15. Choi JW, Koh KS, Hong JP, et al. One-piece frontoorbital advancement with
distraction but without a supraorbital bar for coronal craniosynostosis. J Plast
Reconstr Aesthet Surg. 2009;62(9):
1166-1173.
16. Choi JW, Ra YS, Hong SH, et al. Use of distraction osteogenesis to change
endocranial morphology in unilateral coronal craniosynostosis patients. Plast
Reconstr Surg. 2010;126(3):995-1004.
17. Fearon JA, Varkarakis GM, Kolar J. A comparative study of anterior cranial
vault distraction versus remodeling. J Craniofac Surg. 2014;25(4):1159-1163.
18. Mitchell BT, Swanson JW, Taylor JA. A new, single-stage, distraction-
mediated, cranial vault expansion technique for the multisuture deformity. J
Craniofac Surg. 2015;26(6):1923-1925.

3
CHAPTER
Posterior Cranial Vault
Expansion
Alexander Y. Lin
DEFINITION
■ Posterior plagiocephaly, or flattening of the posterior skull, can be the result
of deformational (positional) forces or of fused sutures (lambdoid
craniosynostosis) (FIGS 1 and 2):
■ This distinction is critical, as deformational plagiocephaly can be improved
nonsurgically with repositioning or orthotics, whereas craniosynostosis
requires surgical repair.1
■ Surgical repair is necessary for craniosynostotic posterior plagiocephaly,
which can be corrected with posterior cranial vault expansion.
■ In craniosynostosis, some early presentations (before 3 and 4 months of age)
may be improved with strip synostectomy and postoperative helmeting,2 and
other presentations may be candidates for posterior distraction osteogenesis,
particularly syndromic patients without adequate bone stock.3
■ Posterior cranial vault remodeling is the set of plastic surgery techniques to
perform open repair in one stage, by designing full-thickness cranial bone
grafts that are neurosurgically elevated and rebuilding the posterior cranial
vault with these grafts via fixation (usually resorbable sutures or plates in
infants, although nonresorbable hardware can be considered in older patients).

FIG 1 • Aerial view of infant’s skull showing calvarial
bones (paired frontals, paired parietals, single occipital)
and sutures (metopic, paired coronals, sagittal, paired
lambdoids).
ANATOMY
■ The normal infant growing skull has five major bones separated by growth
sutures: the metopic suture separates the two frontal bones, which posteriorly
border the bilateral coronal sutures that adjoin the two parietal bones separated
by the sagittal suture at the midline, which forms the lambda where it meets the
bilateral lambdoid sutures that posteriorly define the occipital (FIGURE 1).
■ Craniosynostotic posterior plagiocephaly is usually due to nonsyndromic
lambdoid craniosynostosis (unilateral or bilateral) or multisutural syndromic
craniosynostosis:
■ The resultant head shape is usually brachycephalic (short in the
anteroposterior dimension), with unilateral disease leading to asymmetric
posterior flattening (FIG 2B) and bilateral disease leading to bilateral

posterior flattening.4
■ Cranial index (CI) is defined by cranial width divided by cranial
anteroposterior length and is a relative index to help categorize scaphocephaly
(CI less than 0.76) vs brachycephaly (CI greater than 0.86):
■ Cranial vault asymmetry (CVA) is the difference of the two diagonals from
frontozygomatic suture to contralateral occipital prominence (normal less than
4 mm).
■ Cranial vault asymmetry index (CVAI) is CVA divided by the longer diagonal
(normal less than 3.5).
■ These measurements help assess the preoperative severity and postoperative
outcomes (FIG 3).5
■ The midline sagittal sinus ends posteriorly at the torcula, located at the
occipital protuberance or inion, and then branches laterally along the superior
nuchal line to the bilateral transverse sinuses, which emit emissary veins below
the asterion and posterior to mastoid process, to become the bilateral sigmoid
sinuses:
■ In addition to the venous anatomy, occipital muscles insert at the occipital
protuberance and superior nuchal line, which can also cause bleeding when
stripped (FIG 4).6
PATHOGENESIS
■ Craniosynostosis may be due to genetic or developmental etiologies. Growth
of bone is perpendicular from the direction of the suture; therefore, suture
fusion prevents perpendicular growth, leading to parallel compensatory growth
along the line of the suture:
■ Consequently, in unilateral lambdoid craniosynostosis, compensatory bossing
occurs along the line of the suture, enlarging the ipsilateral mastoid and
contralateral parietal regions, resulting in a trapezoidal head shape from
bird’s-eye view (see FIG 2B).4
FIG 2 • Aerial view of two forms of right posterior
flattening: right posterior deformational forces (A) vs
right unilateral lambdoid craniosynostosis (B).

■ Deformational skull changes occur with a high prevalence because the infant
skull is malleable to allow rapid brain growth (FIG 2A):
■ The “back-to-sleep” supine sleeping campaign has reduced sudden infant
death syndrome (SIDS)7 but has resulted in a higher number of infants with
deformational plagiocephaly.
■ In the setting of craniosynostosis, simultaneous deformational forces, from
infant sleeping position, may unpredictably affect the craniosynostosis head
shape pattern.
NATURAL HISTORY
■ Craniosynostosis occurs about 1 in 2000 live births.
■ The ranges in distribution of fused sutures are8–10
■ Sagittal (40%–57%)
■ Metopic (10%–21.5%)
■ Coronal (15%–30%)
■ Lambdoid (1%)
■ Multisutural (13%)
PATIENT HISTORY AND PHYSICAL FINDINGS
■ Head shape problems manifest early in infancy; rapid infant brain growth
leads to rapid exaggeration of the abnormal vectors of growth.
■ History should include questions about preferred sleeping position, head tilt
related to torticollis, complete closure of eyes when asleep to infer supraorbital
rim abnormalities, and neurological symptoms that may suggest elevated
intracranial pressure (ICP).7

FIG 3 • Schematic of cranial width, cranial AP length,
and cranial diagonals.

FIG 4 • Posterior skull anatomy showing cranial
landmarks and underlying venous sinuses.
■ For posterior plagiocephaly, the physical exam must distinguish the common
deformational plagiocephaly, from the rare lambdoid craniosynostosis.
■ Both can present with unilateral posterior flattening, but deformation causes a
parallelogram-shaped head with ipsilateral forehead protrusion and
contralateral occipital compensation.
■ In lambdoid craniosynostosis, a trapezoidal shape occurs, with ipsilateral
mastoid and contralateral parietal bossing, as well as ipsilateral
posteroinferior movement of the ear, skull base, and foramen magnum (see
FIG 2).4
IMAGING
■ When diagnosis is equivocal, or multisutural craniosynostosis is suspected, CT

scan without contrast, with three-dimensional (3D) reconstructions (FIG 5),
will elucidate each cranial suture.11
■ For syndromic patients, additional studies such as MRI with contrast may be
necessary to rule out anomalous brain anatomy and vasculature that may affect
the surgical approach or require additional neurosurgical procedures.11–13
DIFFERENTIAL DIAGNOSIS
■ Posterior deformational plagiocephaly
■ Lambdoid craniosynostosis (isolated)
■ Lambdoid craniosynostosis (multisutural)
SURGICAL MANAGEMENT
■ The timing of surgery depends on the presenting symptoms but preferably
before 12 months of age to take advantage of the osteogenic potential of the
dura, which dissipates by about 2 years of age.14 In addition, frontofacial
asymmetries are more likely to automatically improve with growth, if
craniosynostosis surgery is performed before 12 months of age.15
FIG 5 • Posterior coronal view of 3D CT scan of infant
with right unilateral lambdoid craniosynostosis, who

also has a right shunt. Note the ipsilateral mastoid and
contralateral parietal expansion, in line with the
synostosed suture.
■ Signs and symptoms of elevated intracranial pressure, especially in
syndromic multisutural patients, may necessitate cranial vault expansion
before 3 months of age.12
■ Patients older than 12 months of age have begun to lose their dural
osteogenic potential and will not heal bone gaps in the reconstruction. They
will need bone grafts to augment the structural reconstruction.14
■ The main objective of surgery is to expand the cranial vault volume from a
posterior approach, as well as to normalize the head shape and appearance of
the posterior skull.
■ The main steps of the operation are:
■ Open approach to the posterior cranium usually via bilateral coronal incisions
■ Design craniotomies that allow volume expansion and reshaping of the
posterior skull
■ Neurosurgical elevation of the bone grafts
■ Rearrangement and fixation of the cranial grafts to reconstruct the posterior
vault
■ Potential bone grafting of bone gaps
■ Closure with possible soft tissue expansion techniques
Preoperative Planning
■ Given that the major morbidity and mortality risk in craniosynostosis surgery
is blood loss due to the infant’s small total blood volume, and the bleeding
nature of extensive cranial osteotomies required for cranial vault
reconstruction,16 it is imperative that prior to surgery, blood bank and
anesthesia are aware and prepared.
■ Institutional blood conservation protocols may include preoperative
medications such erythropoietin, intraoperative medications such as
tranexamic acid, resuscitation protocols that include required ratios of fresh
frozen plasma (FFP) to avoid dilutional coagulopathy, cell salvage blood
recycling for autotransfusion, arterial line monitoring, and multiple lines for
emergent resuscitation if necessary.
■ Neurosurgical team needs to be aware of the plan, including any anomalous

brain anatomy, and standard neurosurgical precautions such as air embolism
monitoring and end-tidal CO2 monitoring.16
FIG 6 • Prone positioning on a well-padded horseshoe
with foam protecting the periorbital regions, with
bilateral coronal incision markings above the hairline
that extend postauricularly.
■ Preoperative imaging can be viewed in rotatable three-dimensional imagery, or
even 3D-printed, for visualization and surgical planning.
Positioning
■ For posterior cranial vault remodeling, prone positioning over a well-padded
horseshoe headrest gives full exposure to the occiput and low craniotomies
while allowing endotracheal tube management and monitoring of the globes to
avoid pressure.
■ Additional foam may be used to protect the periorbital bony prominences
from pressure injury (FIG 6).
■ Alternatively, a modified prone sphinx position may be used, requiring
padding including neck rest, to gain access to both the anterior and posterior
cranial vaults.17
Approach
■ Bilateral coronal incision is usually preferred for full access to the entire

cranium. Rarely, a shorter scalp incision may be used for a limited approach to
a specific portion of the skull.
■ Previous skull incisions (such as previous cranial vault remodeling or shunt
surgery) need to be recognized and incorporated into the incision, to avoid
compromising scalp blood supply.
■ Unilateral lambdoid synostosis with ipsilateral flattening can be approached
with one or more large posterior cranial grafts that are turned 180 degrees or
transposed front to back, to reverse the positions of the flattened side and the
bossed side, improving overall symmetry.
■ Bilateral and unilateral flattening can be approached with a vertex bandeau
transposed to an occipital bandeau. A Marchac forehead template, preferably
from the more protuberant occipitoparietal region, can recreate a new occiput.
■ Barrel-stave technique and radial outfracturing can widen the cranial base and
contour the above bone grafts to customize the reconstruction to fit the patient.
T E C H N I Q U E S
■ Bilateral Coronal Exposure of Posterior Cranium
Markings
■ Bilateral coronal incision is drawn from ear to ear crossing the skull vertex,
keeping it above the hairline and extending it into the inconspicuous
postauricular region if further exposure is necessary.
■ Incorporate previous surgical scars or avoid them with adequate distance.
■ Avoid critical structures such as shunt hardware or significant bony gaps
seen on preoperative imaging.
■ Plan for the possibility of future return via the same coronal incision,
especially in the setting of a syndromic patient who may require multiple-
staged future repairs.
■ Typically, portions of the incision are zigzagged to break up the linear scar
into a less noticeable future scar pattern.
■ Hair may be shaved in full, or only over the planned incision, depending on
parents’ and surgeons’ preferences (see FIG 6).
Incision and Exposure

■ Incorporate techniques to decrease scalp blood loss during the duration of
the surgery.
■ Prior to incision, local anesthetic containing epinephrine appropriately dosed
should be used for vasoconstriction.
■ The incision itself can be made with scalpel or fine-needle point
electrocautery on a low cut setting.
■ Focused bipolar electrocautery, or direct pressure with Raney clips or
temporary stay sutures, can be used to reduce scalp edge bleeding with
minimal effect on hair follicles.
■ The posterior skull can be exposed directly via subperiosteal elevation of the
posterior scalp flap, or staged with an initial subgaleal posterior scalp flap,
followed by elevation of the pericranial flap.
■ The subgaleal plane is relatively bloodless; the subperiosteal plane is
permeated with vascularized channels and muscular attachments, requiring
diligent hemostasis using electrocautery, bone wax, and hemostatic agents
such as thrombin or fibrin.
■ The anterior scalp flap may need to be elevated to the coronal sutures to free
the tension near the ear, allowing the posterior scalp flap to fully deglove and
expose the posterior cranium.
■ The amount of bone exposure depends on the technique used for posterior
cranial vault reconstruction.
■ Usually, the temporalis muscle will need to be elevated subperiosteally out
of its temporal fossa, preferably remaining mostly attached to the frontal
scalp in order to reposition the temporalis muscle automatically when the
frontal scalp is returned during closure.
■ Typically, the posterior scalp flap needs to be exposed to the level of the
inion, where the occipital muscles insert.
■ Both the insertions of the temporalis muscle and the occipital muscles may
have significant bleeding when elevated and require vigilant hemostasis.
■ Bone Transposition
■ Unilateral lambdoid synostosis generally leads to bilateral deformities.
Unilateral flattening is usually associated with contralateral bossing to some
degree.
■ Two types of bone transposition can be used together or separately to

rebalance these asymmetries: inverse (turning 180 degrees or upside down)
transpositions or anterior-to-posterior (AP) transpositions.
Inverse Transpositions
■ Inverse transpositions reverse the positions of the flattened synostotic side
with the contralateral bossing, to improve lateral symmetry (TECH FIG 1).
■ The anterior-most coronal marking should be at the limit of the posterior
asymmetry, where the parietal bones become more symmetric. Markings
should be designed so that the lateral edges of the bone graft segments reach
this anterior coronal line and contain both the bossed portion and flattened
portion to reverse.
■ The posteroinferior osteotomy, or those between bone segments, should
parallel the anterior coronal marking to allow the inverted segment to fit.
■ More than one bone segment may be needed for neurosurgical reasons
(avoiding venous sinuses) or to add more curvature posteriorly by combining
inverse transpositions with AP transpositions.18

TECH FIG 1 • Inverse transpositions rotate each bone
segment upside-down 180 degrees (inverting bone 1
and bone 2), to balance the protrusive and flattened
sides. In this example, this is used in conjunction with
AP transposition (switching AP positions of 1 and 2).

Anteroposterior Transpositions
■ AP transpositions reverse the positions of the more curved vertex segment,
with the flatter occipital segment, to transfer more normal curvature to the
flattened occipital region (TECH FIG 2).
■ Similar to inverse transpositions, the transverse osteotomy markings should
go up to a portion of the parietal bone that is fairly symmetric.
■ The transverse osteotomies should be fairly parallel so that the transposed
pieces can align for bony fixation.
■ Multiple segments can be used in this fashion, with the logical extreme
equivalent to a single vertex thin segment to transpose as an occipital
bandeau.
■ As in the occipital bandeau technique described below, breaking up of the
bone graft may be necessary to recontour and better fit the donor defect.
TECH FIG 2 • AP transposition of segments A (vertex)

and B (occipital). In this example, bone segment B is
further osteotomized into multiple grafts to better fill
the donor defect.
■ Occipital Bandeau
■ Severe brachycephaly may not have any bone segments curved enough to
structurally support an expanded occiput, which undergoes pressure from a
contracting posterior scalp flap and sleeping positions.
■ In this scenario, an occipital bandeau can be harvested from the coronal
curvature at the vertex and transposed to form the new structural occipital
base.15
■ The bandeau is marked as a 2-cm strip near the vertex where the calvarial
curvature is most normal, extending from squamosal suture to squamosal
suture.
■ The bilateral asterion regions must be approached with great care during the
bone elevation due to the underlying venous plexuses.
■ A stairstep can be incorporated near the squamosal sutures to allow further
posterior displacement of the transposed bandeau (TECH FIG 3A).
■ If the bandeau still has significant asymmetry, it can be inverted to transpose
the left and right sides.
■ An age-appropriate Marchac forehead template can be used, preferable from
the more protuberant occipitoparietal region, to recreate a new central occiput
by fixating it to the transposed bandeau (TECH FIG 3B).
■ The transposed bandeau delineates the posterior extent of the reconstructed
cranium.
■ Tongue-and-groove contact with the base using temporary fixation (such as
surgical clamps) can assist to estimate the amount of space left to fill with
bone grafts, before permanent fixation of bandeau.
■ 1After elevating the bandeau and posterior cranium bone grafts, the bandeau
and Marchac grafts are fixed in place. Remaining areas are filled in with
customized bone grafts contoured to fill in the defects (TECH FIG 3C).

TECH FIG 3 • A. Occipital bandeau harvested from
the vertex and neoocciput harvested with Marchac
template from the side with more parietal prominence.
B. Neoocciput and bandeau fixated to create new
posterior extent of the cranium. C. Remaining bone
segments can be recontoured as bone grafts to fill in
the donor defect.
■ Barrel Staves, Contouring, and Bone Grafting
■ Barrel staves can be used in a variety of ways to contour the bony skeleton,

depending on the morphological requirements.
■ Barrel staves can be marked in multiple patterns, including linear and
radial and infractured or outfractured to recontour the skull base or the
large bone pieces.
■ Osteotomies are made with power instruments (Midas Rex, reciprocating
saw) or bone scissors and contoured with Tessier bone benders that can
better control greenstick fracturing and contouring.
■ Other osteotomies include lateral wedges to allow downfracture of
remaining vertex to improve turricephaly (TECH FIG 4A).12
■ In the less frequent scenario of disease mostly limited to one side, a bone
graft containing the depression and radial cuts with outfracture contouring
can improve the defect (TECH FIG 4B).
■ For the occipital skull base, vertical barrel staves allow outfracturing and
widening of the base, to better approximate the expanded occiput (TECH
FIG 4C).
■ Plating systems can be used to maintain the expanded barrel staves and
reduce relapse of the expansion.17
■ Bone defects can be minimized with split or full calvarial bone pieces, inner
table particulate bone grafts, bone allograft, or other bone autografts (TECH
FIG 4D).
■ Bone graft pieces may be fixated with hardware or sutures and particulate
bone graft with plates or topical fibrin glue sealant.

TECH FIG 4 • A. For syndromic associated
turricephaly, lateral wedge osteotomies can allow
downfracture to lower the vertex; note skull base
vertical barrel staves to widen occiput. B. For
unilateral disease with minimal contralateral changes,

a unilateral bone graft with radial barrel staves allows
direct recontouring. C. Vertical barrel staves at skull
base can be contoured with Tessier bone benders,
along with contouring of bone segments. D. An
example of occipital bandeau with neoocciput and
bone grafts incompletely fill the donor defect; shaded
areas indicate where additional bone grafting is
needed.
■ Bony Fixation and Soft Tissue Expansion for
Closure
■ Bone fixation is usually performed with resorbable plating systems and
resorbable sturdy sutures (2-0 polydioxanone).
■ Approximated bones can be temporarily held in place with surgical clamps
and the plate with another clamp.
■ Holes can be drilled (for the plating system or sutures) and then plated or
sutured before removing the surgical clamps.
■ Bone grafts can also be wired temporarily, to aid in plate or suture fixation.
In an older patient, nonresorbable titanium hardware can be used.
■ Scalp may need to be expanded with transverse galeal scoring to allow AP
lengthening.
■ Each transverse score should be at least 1 to 2 cm from the previous one, to
avoid injury to the blood supply.
■ Scoring may be performed with unipolar electrocautery on cutting, and
blunt spreading can be used to widen the galeal score.
■ Avoid large blood vessels during scoring by interrupting the transverse
score where there are visible blood vessels.
■ Both anterior and posterior scalp flaps may need galeal scoring to achieve
soft tissue closure without undue tension on the bone reconstruction.
■ Prior to final closure, check for final hemostasis.
■ The anesthesia team should perform a Valsalva maneuver to detect dural
tears and cerebrospinal fluid (CSF) leaks.
■ The bilateral temporalis muscles need to be resuspended to prevent temporal
hollowing.

■ If they are significantly attached to the anterior scalp flap, they may not
need significant resuspension. They can be sutured to each other or to
resorbable plates.
■ Closure over a scalp drain may be performed through a stab incision away
from the coronal incision, remaining above the hairline.
■ The strength layer is the galea, which should be approximated with
interrupted slow-resorbable sutures (such as 3-0 polyglactin or 3-0
poliglecaprone).
■ Revision surgery may lack a clear galeal plane, and in that scenario, the
scarred layers including the dermis should be included for strength.
■ The skin can be approximated with running resorbable suture (such as 4-0
plain gut or 5-0 chromic gut).
■ For some closures, temporary stay sutures to hold the incision together
may be needed and then removed after the above layers closed.
■ The incision is dressed with antibiotic ointment and petroleum gauze,
followed by rolled gauze and tube gauze covering the entire head with a
window for the face.
■ Excess rolled gauze under the chin should be checked or cut to prevent
constriction.
PEARLS AND PITFALLS
Hemostasis
■ Vigilant blood loss monitoring and communication among all
members of the team is critical: blood bank, anesthesia, plastic
surgery, neurosurgery, and the ICU.
■ Blood bank needs to have adequate matched blood products
including FFP, to avoid dilutional coagulopathies in the setting of
significant transfusion.
■ Care teams need to attentively assess vitals, labs, urine output, and
drain output in the immediate postoperative period.
Exposure
■ Plan scalp incisions carefully, especially in syndromic patients who
may need staged future surgeries for the anterior cranium.
■ Preoperative imaging is especially important in syndromic patients
with anomalous bone, brain, and vasculature; imaging determines the
safe inferior extent of posterior osteotomies while avoiding
underlying venous structures.

■ Areas of fused and open sutures may have adherent periosteum and
dura, requiring careful navigation to avoid injury.
■ Irrigate periosteal flaps during surgery to avoid desiccation.
Bone
■ The posterior cranium has significant venous sinuses and emissaries
that require caution during elevation to avoid air embolism and
bleeding.
■ Temporary wide and flat surgical clamps can hold together multiple
bone grafts and resorbable plates, while drilling and fixation take
place.
■ Malleable retractors protect the dura during drilling, bone suturing,
and affixing hardware.
■ For additional bone, calvarial grafts can be split with thin
osteotomes; particulate bone can be harvested from the inner table
with a low-speed drill.
Closure
■ Prior to closure, establish hemostasis; perform Valsalva to examine
for CSF leak; complete counts; and irrigate.
■ The drain may be left unsutured because it will be removed prior to
discharge.
■ Some cases will have no drain to avoid negative suction near the
dura.
■ Airway and globe protection during and after these extended prone
position cases is especially important during and immediately after
surgery.
POSTOPERATIVE CARE
■ Overnight monitoring in the intensive care unit (ICU) includes vitals, arterial
line, urine output, drain output, serial blood count, and coagulation assays, for
possible further transfusions. Neurosurgical monitoring includes neurological
checks and serum sodium.
■ Transfer to floor on postoperative day (POD) 1. Dressings and drain removed
on POD 2 or POD 3 before going home with daily dressing changes. Patients
who are very active or prone to injury may benefit from a helmet for additional
postoperative protection.
OUTCOMES
■ Nonsyndromic posterior flattening has good long-term outcomes in terms of
bone healing, relapse, and revision rate:
■ Lambdoid craniosynostosis has very low reported revision rates.13,15
■ Syndromic patients with anomalous bone growth are more likely to require

surgical revisions.14,19
COMPLICATIONS
■ Major morbidity and mortality risks are due to blood loss from multiple
osteotomies in the small infant with low total blood volume.
■ Infection is uncommon. If detected, the patient requires a washout in the
operating room and antibiotics, with attempts to maintain the large bone grafts
if possible, given their valuable structure.
■ Suboptimal healing or resorption of bone grafts may lead to bone gaps that
require future cranioplasty.
■ Relapse, which is more prevalent in syndromic patients with anomalous
growth, can lead to future revisions.
REFERENCES
1. Tamber MS, Nikas D, Beier A, et al. Congress of Neurological Surgeons
systematic review and evidence-based guideline on the role of cranial molding
orthosis (helmet) therapy for patients with positional plagiocephaly.
Neurosurgery. 2016;79:E632-E633.
2. Berry-Candelario J, Ridgway EB, Grondin RT, et al. Endoscope-assisted strip
craniectomy and postoperative helmet therapy for treatment of
craniosynostosis. Neurosurg Focus. 2011;31:E5.
3. Ong J, Harshbarger RJ III, Kelley P, George T. Posterior cranial vault
distraction osteogenesis: evolution of technique. Semin Plast Surg.
2014;28:163-178.
4. Huang MH, Gruss JS, Clarren SK, et al. The differential diagnosis of posterior
plagiocephaly: true lambdoid synostosis versus positional molding. Plast
Reconstr Surg. 1996;98:765-774.
5. Rogers GF. Deformational plagiocephaly, brachycephaly, and scaphocephaly.
Part I: terminology, diagnosis, and etiopathogenesis. J Craniofac Surg.
2011;22:9-16.
6. Chen EH, Gilardino MS, Whitaker LA, Bartlett SP. Evaluation of the safety of
posterior cranial vault reconstruction. Plast Reconstr Surg. 2009;123:995-
1001.
7. Weissler EH, Sherif RD, Taub PJ. An evidence-based approach to
nonsynostotic plagiocephaly. Plast Reconstr Surg 2016;138:682e-689e.
8. Lee HQ, Hutson JM, Wray AC, et al. Changing epidemiology of
nonsyndromic craniosynostosis and revisiting the risk factors. J Craniofac

Surg. 2012;23:1245-1251.
9. Salehi A, Ott K, Skolnick GB, et al. Neosuture formation after endoscope-
assisted craniosynostosis repair. J Neurosurg Pediatr. 2016;18:196-200.
10. Heuze Y, Holmes G, Peter I, et al. Closing the gap: genetic and genomic
continuum from syndromic to nonsyndromic craniosynostoses. Curr Genet
Med Rep. 2014;2:135-145.
11. Mazzola C, Baird LC, Bauer DF, et al. Congress of Neurological Surgeons
systematic review and evidence-based guideline for the diagnosis of patients
with positional plagiocephaly: the role of imaging. Neurosurgery.
2016;79:E625-E626.
12. Jarrahy R, Kawamoto HK, Keagle J, et al. Three tenets for staged correction
of Kleeblattschadel or cloverleaf skull deformity. Plast Reconstr Surg.
2009;123:310-318.
13. Fearon JA, Dimas V, Ditthakasem K. Lambdoid craniosynostosis: the
relationship with chiari deformations and an analysis of surgical outcomes.
Plast Reconstr Surg. 2016;137:946-951.
14. Persing JA. MOC-PS(SM) CME article: management considerations in the
treatment of craniosynostosis. Plast Reconstr Surg. 2008;121:1-11.
15. Goodrich JT, Argamaso R. Lambdoid stenosis (posterior plagiocephaly) and
craniofacial asymmetry: long-term outcomes. Childs Nerv Syst. 1996;12:720-
726.
16. Stricker PA, Fiadjoe JE, Davis AR, et al. Reconstituted blood reduces blood
donor exposures in children undergoing craniofacial reconstruction surgery.
Paediatr Anaesth. 2011;21:54-61.
17. Persing JA, Delashaw JB, Jane JA, Edgerton MT. Lambdoid synostosis:
surgical considerations. Plast Reconstr Surg. 1988;81:852-860.
18. Vander Kolk CA, Carson BS. Lambdoid synostosis. Clin Plast Surg.
1994;21:575-584.
19. Gosain AK, Moore FO, Hemmy DC. The Kleeblattschadel anomaly in Apert
syndrome: intracranial anatomy, surgical correction, and subsequent cranial
vault development. Plast Reconstr Surg. 1997;100:
1796-1802.

4
CHAPTER
Posterior Cranial Vault
Distraction Osteogenesis
Richard A. Hopper and Amy Lee
DEFINITION
■ Posterior cranial vault distraction osteogenesis (PVDO) increases intracranial
volume through gradual expansion of a circumferential cranial osteotomy using
manually activated buried distraction devices.1
■ PVDO is indicated in patients with premature fusion of multiple cranial
sutures (synostosis) resulting in craniofacial dysmorphology, cephalocranial
disproportion, and the risk of increased intracranial pressure.
ANATOMY
■ The anterior fontanelle is at the junction of the coronal and sagittal sutures.
■ The pterion is an indentation at the anterior portion of the temporal bone
corresponding intracranially to the lesser wing of the sphenoid.
■ The petrous ridge is a focal elevation of the dural adhesion to the skull base at
the posterior temporal bone in line with the inferior aspect of the lambdoid
suture.
■ The sagittal venous sinus of the brain is typically located in the upper midline
but can be asymmetric in complex cases.
■ The transverse venous sinuses are usually located in the middle of the
posterior cranium but can be inferiorly displaced closer to the skull base in
syndromic cases such as Apert and Pfeiffer syndromes.
■ The confluence of the sagittal and transverse sinuses is the torcula.
PATHOGENESIS
■ Brachy-turricephaly describes a cranial shape with restricted growth in the
anteroposterior direction (brachy = short) with compensatory growth in the

superior direction (turri = tower).
■ The development of brachycephaly typically results from premature fusion of
one or more of the posterior cranial sutures (lambdoid and sagittal) in
association with fusion of one or more of the anterior coronal sutures.
■ The associated turricephaly results from compensatory vertical expansion of
the developing brain through overexpansion and bone effacement in the
squamosal and frontozygomatic sutures as well as the anterior and posterior
fontanelles.
■ Primary skull base anomalies in the pterion and petrous ridges of syndromic
cases exacerbate this deformity.
■ Most PVDO procedures are performed on patients with brachy-turricephaly
associated with FGFR2 mutations such as Crouzon, Apert, and Pfeiffer
syndromes.
■ Complex multiple suture synostoses such as the kleeblattschädel deformity or
Mercedes pattern (sagittal and bilateral lambdoid) synostosis can also benefit
from PVDO.
NATURAL HISTORY
■ Without surgical treatment through cranial release or expansion, the brachy-
turricephaly deformity is progressive in the first years of life.
■ Eventual closure of the fontanelles and patent sutures prevents continued
compensatory growth, and cephalocranial disproportion occurs, resulting in
increased intracranial pressure.
■ Frontal surgeries such as fronto-orbital advancement and monobloc procedures
provide less intracranial expansion than does PVDO but can be performed after
PVDO if further expansion is required.
■ PVDO provides more intracranial volume expansion per millimeter
advancement than frontal surgeries due to the increased surface area of the
transported bone.2,3
■ The severe thumbprinting of the posterior calvarium seen in patients prior to
PVDO will progress without intervention.
■ With the improved cephalocranial proportion achieved by PVDO, this
thumbprinting often resolves soon after activation is complete (FIG 1).
PATIENT HISTORY AND PHYSICAL FINDINGS
■ Interdisciplinary assessment of airway, feeding, genetics, and potential
associated anomalies must be performed before PVDO.

■ Neurosurgical assessment is completed for associated conditions such as
Chiari malformation or hydrocephalus.
■ Patients with documented hydrocephalus will require appropriate treatment
with a cerebrospinal fluid (CSF) shunt procedure prior to PVDO to prevent
progressive cranial deformity and nonhealing of the cranial expansion defects
postoperation.
■ Patients with documented symptomatic Chiari malformations will require
treatment before PVDO, but in rare cases, bone decompression of the foramen
magnum can be performed simultaneously through the coronal incision.

FIG 1 • CT scan images of a 4-month-old patient with
pansynostosis and turribrachycephaly undergoing
staged posterior and anterior cranial vault expansion. A.
Prior to posterior vault distraction, the circumferential
posterior osteotomy is bridged by paired parallel
internal distraction devices. Note the preoperative
posterior calvarial thumbprinting. B. At the end of
activation at a rate of 1 mm/day, the posterior vault has

been expanded. Note the resolution of thumbprinting
from increased bone formation with increase of the
intracranial volume and decrease of the intracranial
pressure. C. After the 2-month consolidation period, the
osteotomy gap has largely healed. D. Age 18 months
after fronto-orbital advancement. The posterior vault
expansion in infancy created sufficient intracranial
space to allow the anterior vault surgery to be
performed at a later age, when stability and longevity of
the result are improved.
■ Asymptomatic Chiari malformations can improve with PVDO or be directly
decompressed during the same procedure.4,5
■ Whenever possible, a full ophthalmologic examination including dilated
funduscopy or visual evoked potentials should be performed prior to
intracranial surgery.
IMAGING
■ A low-dose three-dimensional CT scan can help in osteotomy marking, device
placement, and vector planning.
■ The thickest bone along the planned osteotomy is optimal for screw fixation of
the devices.
■ Vector planning on the images should optimize volume expansion and avoid
shearing of the dura, and step-off deformities (see Technique section).
■ A contrast CT scan or magnetic resonance angiogram is indicated for
syndromic patients to assess the location of the transverse and sagittal sinuses,
which can be more inferior and off midline respectively in these patients.
■ Posterior circular cranial defects on CT scan can be indicative of anomalous
intracranial venous drainage to the skin, and disruption of this drainage should
be avoided to prevent increased intracranial hypertension6,7 (FIG 2).
■ Virtual computer planning with or without stereolithographic models, cutting
guides, and sinus marking can be beneficial in complex cases.
■ Stereolithographic models can allow prebending of distraction device
footplates to ensure a parallel vector.
■ Serial lateral plain film cephalograms are effective in following cranial

expansion and to ensure devices remain stable on the cranium in cooperative
patients.
SURGICAL MANAGEMENT
■ PVDO treats the posterior volume restriction associated with brachy-
turricephaly to permit unrestricted brain growth in infancy.
■ Without the increased intracranial volume (ICV) achieved from a preceding
posterior cranial expansion, turricephaly is often not able to be addressed with
a frontal surgery alone due to an insufficient ICV to displace the brain
inferiorly.
■ PVDO is typically performed on patients with multiple suture synostosis in the
first year of life to allow frontal surgeries such as fronto-orbital advancement
or monobloc to be done at an older age when stability is more reliable and the
complication and relapse rate is decreased.8
FIG 2 • A patient with Apert syndrome prior to posterior
vault distraction. A. A circular defect (arrow) in the
posterior calvarium was suggestive of anomalous
transcranial venous drainage. B. The communication
between scalp and transverse sinus was confirmed on
sagittal view (arrow) and on MRI with contrast. To avoid

venous congestion, the draining vein was preserved
during the scalp dissection.
■ PVDO can be performed in appropriate patients in the first few months of life
as long as there is sufficient bone to mount the distraction devices.
■ If cranial bone is insufficient to mount devices due to bone effacement,
preceding treatment of hydrocephalus or early strip craniectomy release may
be required to temporarily achieve cephalocranial balance and subsequent bone
deposition.
Preoperative Planning
■ An end-tidal CO2 of 30 mm Hg or less will decrease both intracranial and
venous pressure, which will facilitate the craniotomy and decrease bleeding.
■ The fluid shift expectations and anticipated blood product replacement needs
should be discussed by the team.
■ In many cases, blood transfusion can be avoided in posterior cranial vault
distraction (PCVD) due to the limited craniectomy required.
Positioning
■ The patient is placed in a prone position with appropriate chest, pelvis, and
face padding (FIG 3).
■ The neck is maintained in a neutral position to avoid venous compression and
an increased risk of venous air embolism (VAE).9,10
■ A transesophageal or precordial Doppler can help in early detection of VAE.
■ The endotracheal tube is secured in place with a circummandibular suture or
wire to avoid displacement.
Approach
■ The cranium is exposed from the coronal sutures and fontanelle anteriorly to
the insertion of the neck musculature posteriorly through a zigzag coronal
incision.
■ Laterally, the pterions and petrous ridges are identified as key landmarks.
■ A subperiosteal dissection will preserve the vascularity of the periosteum and
increase soft tissue thickness over the devices but will result in more blood
loss.
■ A subgaleal dissection has less blood loss but will offer thinner scalp

protection of the devices, and the periosteum can be compromised during the
dissection.
■ A subgaleal approach is recommended if there are multiple cranial defects
from thumbprinting to avoid damage to the dura.
FIG 3 • A. The patient’s face and forehead are
protected with foam padding to avoid any pressure on
the globes. B. The neck is supported in a neutral
position with the head level with the heart in order to
minimize the risk of venous air embolism.
T E C H N I Q U E S
■ Osteotomy
■ Unlike standard cranial vault remodeling, with PCVD, the posterior cranial
bone is not dissected from the dura.
■ A circumferential full-thickness osteotomy is marked from the anterior
fontanelle inferiorly across the squamosal suture to the temporal bone,
posteriorly just above the petrous ridge, along the inferior occipital bone
just above the neck muscles and then returning to the anterior fontanelle on
the contralateral side with a symmetrical pattern.
■ The lower the osteotomy on the occiput, the more volume expansion and
posterior fossa decompression will be obtained.

■ Care must be taken to identify the venous sinuses through preoperative CT
or MRI scanning.
■ The osteotomy crosses the transverse sinuses lateral in the region of the
petrous ridges.
■ The posterior osteotomy should be inferior to the torcula but superior to the
skull base. One of the major benefits of PCVD is that the occipital bone does
not need to be dissected off the torcula, minimizing risk of exsanguination.
■ There is often a keel or invaginated bone at the midline of the posterior
osteotomy at the level of the skull base that may require careful rongeuring or
drilling to remove (TECH FIG 1).
TECH FIG 1 • The inferior portion of the
circumferential osteotomy for posterior vault
distraction should go as close to the skull base as
possible. This will achieve maximum volume
expansion and place the osteotomy below the torcula
of the sinuses. In many syndromic patients, there is a
midline bone invagination at the junction of the skull
base (arrow) that needs to be carefully dissected to
avoid violation of the dura.

■ Device Placement
■ The most stable bone in infant patients with syndromic synostosis is
typically in the region of the temporal bone below the squamosal suture or in
the parietal bone just above the suture.
■ Paired, symmetric devices are placed across the osteotomy along the region
of stable bone with parallel vectors when viewed from both the side and the
top (TECH FIG 2A,B).
■ The activation arms can extend either anteriorly or posteriorly depending on
surgeon preference.
■ Three 3- or 4-mm screws are placed in each footplate of the distraction
device with protection of the underlying dura.
■ The undersurface of the footplate bone is checked for any protruding screw
points that can be removed with a rongeur if prominent.
■ The paired temporal devices are then activated approximately 5 mm.
■ If the osteotomy across the top of the cranium is opening symmetrically, no
further devices are required and the devices are deactivated.
■ If the superior osteotomy does not open symmetrically with the temporal
osteotomy on device activation, additional devices can be applied more
superiorly for symmetric activation and to decrease the likelihood of device
strain and footplate loosening.
■ The majority of cases can be managed with one device pair if the bone is
sufficiently rigid.
■ On vertex view, the vector of the devices is parallel and tangential to the
osteotomy (TECH FIG 2C).
■ On lateral view, the vector is tangential to the vertex osteotomy to avoid a
step deformity with activation (TECH FIG 2D).

TECH FIG 2 • Transparent CT scan images of a
patient immediately after circumferential osteotomy
and placement of distraction devices. A. On the lateral
view, the devices (in red) are seen parallel to each
other and the vector is planned to avoid a step-off
deformity as the vertex osteotomy is opened. B. Seen
on the vertex view, a second pair of devices was
needed in this patient to achieve even opening of the
osteotomy. All four devices are parallel to the tangent
of the widest part of the skull where the osteotomy is
located. C. Intraoperative vertex view. Straight
elevators can be placed against the parietal bone of
the patient to ensure parallel positioning. The lateral
osteotomy is then planned at the tangent of where the
elevators touch the bone. D. Intraoperative lateral