Keywords
coronal craniosynostosis - endoscopic repair - syringe retractor - novel technique
- strip craniectomy
Introduction
Craniosynostosis is a rare condition affecting 1 in 2,000 to 2,500 live births.[1] It involves premature fusion of one or more cranial sutures, which results in uneven
growth at the other suture sites and abnormal enlargement of the head. Nearly 85%
of craniosynostosis patients are nonsyndromic due to underlying de novo genetic mutation
or single nucleotide alteration.[2]
[3] The remainder are syndromic, which include but are not limited to Apert, Down's,
Muenke, Crouzon, and Pfeiffer etc. The unilateral coronal synostosis (anterior plagiocephaly)
is the second most common subtype after sagittal synostosis. It accounts for almost
one-third of cases of nonsyndromic craniosynostosis. The incidence of unilateral coronal
craniosynostosis is 1 in 10,000 live births and it is more common in females.[4]
[5] The most common mutations involved in nonsyndromic unilateral coronal craniosynostosis
are FGFR3, TWIST1, and TCF12.[2]
The primary treatment for craniosynostosis involves surgical intervention. There are
multiple surgical options available, ranging from complex cranial vault reconstruction
to minimally invasive endoscopic suturectomy/strip craniectomy. The principle of endoscopic
surgery relies on the undercutting of the fused suture followed by helmet therapy
to allow remodeling over time. It is being readily picked up by surgeons across the
world owing to shorter hospital stays, minimal blood loss, less scarring and blood
loss, better aesthetics, and being minimally invasive.
For endoscopic repair, although various retractors have been described in the literature
such as the J&B Dural-Scalp retractor,[6] Lighted retractor[7] etc., herein we describe endoscopic repair of unilateral coronal craniosynostosis
using a novel cut-out syringe scalp retractor. It is durable, cost-effective, and
readily available in resource-constrained setups.
Case Discussion
A 3-month-old female child came with complaints of abnormal head shape, which was
gradually progressing with time ([Fig. 1]). Clinical, neurological, and fundus examinations were within normal limits. Ultrasound
of abdomen, echocardiography, and ophthalmological examination were normal. There
were no clinical signs of intracranial hypertension and no evidence of hydrocephalus
in the CT of brain. The brain parenchyma was normal.
Fig. 1 A 3-month-old female child came with complaints of abnormal head shape, which was
gradually progressing with time. Clinical examination showed right frontal prominence
with underlying fused right coronal suture.
Three-dimensional reconstruction of brain CT bone window showed flattening of the
right frontal bone at the site of fused coronal suture with ipsilateral enlargement
of the right temporal bone and contralateral bossing of the left frontal bone ([Fig. 2]). In addition, there is an elevation of the right greater wing of the sphenoid bone
and foreshortened anterior skull base ([Fig. 3]). A diagnosis of right unilateral coronal craniosynostosis was made. The patient
was planned for endoscopic strip craniectomy followed by 12 months of helmet therapy.
Fig. 2 On three-dimensional reconstruction of brain CT, the right frontal bone appears flattened
due to fused coronal suture with ipsilateral enlargement of the right temporal bone
and contralateral bossing of the left frontal bone.
Fig. 3 Three-dimensional reconstruction of brain CT showing reduced mediolateral orbit dimension
on the affected side (top row) and elevation of the right greater wing of sphenoid
bone with a decreased anteroposterior dimension of the anterior skull base.
The patient was placed in the supine position and a curvilinear incision was made
overlying the fused suture at the level of stephanion ([Fig. 4]). After opening the galea, a soft, malleable, cut-out syringe scalp retractor was
placed beneath the galea. A subgaleal plane is created with the help of the retractor.
Subsequently, a burr hole is made with the help of a cutting drill (40 mm), and the
dura is separated from the underlying fused suture with the help of a Penfield dissector.
The burr hole osteotomy is then enlarged with the help of a Kerrison rongeur. Any
bleeding from the diploe is controlled using bone wax as illustrated ([Fig. 5]).
Fig. 4 The patient was positioned supine and a curvilinear incision was made over the fused
suture at the level of the stephanion.
Fig. 5 A new cut-out syringe scalp retractor is displayed on the left. The novel retractor
is placed beneath the galea after opening it. The retractor helps to create a subgaleal
plane (top row). Subsequently, a burr hole is made with the help of a cutting drill
(40 mm), and the dura is separated from the underlying fused suture with the help
of a Penfield dissector. The burr hole osteotomy is then enlarged with the help of
a Kerrison rongeur. Any bleeding from the diploe is controlled using bone wax as illustrated
(middle row). A diamond drill is utilized to perform the strip craniectomy, and the
last image on the right shows a complete strip craniectomy with absolute hemostasis
(last row).
With the self-retaining, malleable cut-out syringe scalp retractor beneath the galea
aponeurotica and the Penfield dissector separating the dura from the fused suture
site, a diamond drill is introduced as shown in the pictorial illustration ([Fig. 6]). The osteotomy is enlarged medially to reach the anterior fontanelle and laterally
up to the squamosal suture using the diamond drill. The hemostasis is achieved using
bone wax from the bony diploe. The postoperative scan shows adequate suturectomy.
At 12 months, after helmet therapy, slight prominence was observed in the right frontal
area along with rounding of the occipital bone below the vertex, and bilateral symmetry
of greater wing of sphenoid bone was noted ([Fig. 7]).
Fig. 6 A self-retaining, malleable cut-out syringe scalp retractor is pictured below the
galea aponeurotica. A Penfield dissector separates the dura from the fused suture
site. A diamond drill is used for strip craniectomy.
Fig. 7 The top row shows the clinical picture (right lateral and frontal view) of the patient.
The first two images on the left are the preoperative pictures and the last two images
on the right are taken at a 12-month follow-up visit. The bottom row shows the postoperative
three-dimensional reconstruction of brain CT (axial and right lateral view). The first
two images on the left are from the immediate postoperative period. The last two images
on the right are taken at 12-month follow-up showing rounding of the occipital bone
below the vertex and bilateral symmetry of greater wing of sphenoid bone.
Discussion
Cranial sutures are fibrous joints that serve as growth plates and as a site of osteogenesis.[8]
[9] The growth of the cranial vault is genetically regulated and any disturbance in
these pathways leads to premature fusion of these fibrous joints.[8] Recent consensus demonstrates that fusion of the fibrous joints at the cranial vault
is pathognomonic for craniosynostosis.[10] The diagnosis is by clinical observation. Radiological imaging (skull X-ray, three-dimensional
CT reconstruction) is essential for surgical planning, as an adjunct when diagnosis
is doubtful, and as a baseline reference for future evaluation.[11]
In cases of unilateral coronal craniosynostosis, there is flattening at the site of
fused joints, ipsilateral bulging of the squamosal temporal bone, and prominence of
the contralateral frontal bone ([Fig. 2]). The elevation of the ipsilateral greater wing of the sphenoid along with the reduced
anteroposterior dimension of the anterior cranial fossa is considered pathognomonic
for unilateral coronal craniosynostosis. Our case exhibits similar findings (as shown
in [Fig. 3]). The treatment for craniosynostosis remains surgical. The surgical armamentarium
includes distraction osteogenesis, fronto-orbital advancement (FOA), strip craniectomy,
and endoscopic suturectomy. Distraction osteogenesis has its disadvantages, including
multiple revision surgeries, the risk of intracranial migration of metallic implants,
incomplete remodeling of the cranial vault, and surgical site infections, which add
to surgical morbidity.[12] Reconstruction of the cranial vault involves complex craniofacial alignment that
is time-consuming and associated with significant blood loss and longer postoperative
stays.
Owing to these limitations, there was a preference toward less invasive procedures.
The concept of strip craniectomies was first described in 1890.[13] However, the endoscopic strip craniectomies were first introduced in late 1900 by
Vicari, and Jimenez and Barone.[14]
[15] For endoscopic craniosynostosis repair, it is advisable to perform strip craniectomy
before 3 months of age.[14] The rapid brain growth thereafter corrects the pre-surgical calvarial deformities
after the removal of the fused fibrous joints. The postoperative helmet therapy ensures
adequate remodeling and correction of the skull deformity over time.
The main aim of endoscopic surgery is to swiftly address the progression of calvarial
and facial dysmorphism. It is imperative to ensure that the cranial base sutures remain
unaffected before considering endoscopic repair for a patient.[16] The width of strip craniectomy for coronal craniosynostosis should be at least 1 cm.
Endoscopic repair is gaining popularity among neurosurgeons and the parents owing
to shorter hospital stays, early recovery, less scarring and blood loss, and being
minimally invasive. A systematic review and meta-analysis have confirmed these findings
in cases with sagittal and non-sagittal synostosis.[17]
[18] The endoscopic repair offers equivocal/comparable outcomes with respect to cranial
vault reconstruction, which has been validated by multiple studies.[19]
[20]
[21]
[22] It is more cost-effective as compared to cranial vault remodeling.[23]
[24]
[25]
The endoscopic strip craniectomy does not require any special instruments for the
procedure. The standard endoscopic trolley comprises of zero-degree rod-lens scope,
a camera unit, a cold light source, and a high-definition monitor, which are available
at the majority of the institutes performing routine cranial and spinal neurosurgery
cases. For craniosynostosis cases, there are specifically designed retractors, viz,
J&B Scalp-Dural retractor,[6] lighted speculum[7] etc. However, procurement of these could be difficult in a resource-constrained
setup. We advocate the use of a cost-effective, durable, reusable, and malleable scalp
retractor whose cost is one-fifth of 1 US dollar. The retractor is made from a 10-cc
to 20-cc syringe and features a semi-circular plastic sheet with thread holes for
easy removal post-surgery. The device can be sterilized using plasma sterilization
or freshly made for each procedure, ensuring sterility. We found this scalp retractor
to be extremely useful in the case of endoscopic strip craniectomy ([Fig. 5]). After initial incision and dissection, the retractor can be inserted into the
subgaleal plane and further dissection can be done with the help of this novel retractor.
The shape of the scalp retractor conforms to the galea, preventing the blood from
seeping in from superior and lateral direction. Hence, it helps in maintaining a bloodless
surgical field, which aids in appropriate visualization using an endoscope. The usage
of this disposable self-retaining scalp retractor is extremely cost-effective and
has not been described in the literature previously. The novel retractor is designed
to improve surgical precision, visualization, and adaptability, while being affordable,
disposable, and widely available, particularly in resource-constrained settings.
Although endoscopic surgery has its benefits, few studies have doubted the efficacy
of this procedure. The reasons cited include a lack of adequate skull molding in the
follow-up period, failure to achieve hemostasis far lateral to the strip craniectomy
site, and comparable vault expansion to open surgery.[18]
[20]
[26] In addition, more favorable neurological outcomes have been reported for whole vault
cranioplasty when performed before 6 months of age as compared to the endoscopic/open
strip craniectomy.[27] However, we believe that endoscopic surgery since its inception in the late 1900s
has evolved significantly and more neurosurgeons are adopting endoscopic repair. Future
prospective studies will better elucidate the impact of endoscopic repair on cosmetic
outcomes.
Conclusion
Endoscopic strip craniectomy is safe, causes less scarring and blood loss, is associated
with fewer complications, and recovery is swift. The long-term outcomes of endoscopic
repair are comparable to the open cranial vault reconstruction in the appropriate
patient population. Our novel cut-out syringe scalp retractor should be considered
for endoscopic repair cases in resource-constrained setups, particularly in developing
countries.
