Endoscopic Assisted Strip Craniectomy

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Overview         :         Fact Sheet         :        

THE SURGERY

Endoscopic-Assisted Strip Craniectomy For Craniosynostosis 

Faizi A. Siddiqi, MD FACS
Chief, Pediatric Plastic Surgery/Craniofacial Surgery
Division of Plastic Surgery
The University of Utah    

Craniosynostosis is defined as the premature closure of a calvarial suture.  The estimated frequency of craniosynostosis is approximately 0.4/1000.  The resulting head shape depends upon the type and number of cranial sutures involved.  Virchow in 1951 coined the term “craniostenosis” and theorized that bone growth normally occurs perpendicular to a suture.  When a suture closes prematurely, Virchow stated that growth then occurs parallel to that suture.  This results in a specific head shape (fig 1). The diagnosis is confirmed with a CAT scan of the head with 3-D reconstruction (fig 2).  The most common type of craniosynostosis is sagittal craniosynostosis, occurring with a frequency of 1 per 1000 live births.  The coronal, metopic and lambdoid sutures may also fuse prematurely in this order of decreasing frequency.  Since deformational plagiocephaly can also result in an abnormal head shape, the diagnosis sometimes can be challenging.  This especially true of posterior positional plagiocephaly and lambdoid craniosynostosis.  However with a careful examination and a history of persistent and progressive abnormal head shape will aid in diagnosis.

In contrast to deformational plagiocephaly in which abnormal head shape  can be corrected with repositioning or helmet therapy, craniosynostosis can only be corrected with surgery.  Surgery is performed to correct head shape and reduce the risk of raised intracranial pressure.  The risk of raised intracranial pressure increases with the number of sutures fused (fig 3).  The cranial sutures are the sites where cranial growth occurs in response to a growing brain.  The dura plays an important role in regulating growth at the sutures.  Since brain volume triples during the first twelve months,  intracranial pressure may increase if the cranial vault cannot accommodate the growing brain due to one or more sutures that have fused prematurely (fig 4).

Corrective surgery for craniosynostosis is done also to restore normal appearance, and not for cosmetic improvement.  According to the American Medical Association, cosmetic surgery is “surgery performed to reshape normal structures of the body to improve the patient’s appearance and self-esteem” while “reconstructive surgery is performed on an abnormal structure of the body caused by congenital defects… to improve function and approximate normal appearance”.  It is not normal to have head shapes secondary to craniosynostosis with the associated risk of raised intracranial pressure.  Premature closure of the sagittal suture typically results in a long a narrow head shape referred to as scaphocephaly (fig 5). With more severe forms of metopic craniosynostosis, a triangle shaped head or trigonocephaly occurs (fig 6).  Premature closure of the coronal suture results in a flat and retruded forehead with a retruded supraorbital rim, or plagiocephaly (fig 7). When the entire coronal suture is involved, the head appears tall and broad or turricephalic (fig 8).  Premature closure of the lambdoid suture results in occipital flattening which must be distinguished from positional plagiocephaly as mentioned earlier.

The use of endoscopes to assist in the surgical management of various disorders has been widely utilized in the fields of general surgery, urology, thoracic surgery and ENT surgery.  The use of endoscopes in the management of craniosynostosis has been a relatively recent advance.  Many surgical techniques have been introduced for the surgical management of craniosynostosis since L.C. Lane first described a procedure to release a prematurely fused suture in 1892.  The type of procedure for the correction of scaphocephaly secondary to sagittal craniosynostosis depends  upon the age of presentation. An open strip craniectomy is generally performed before 4-5 months of age through a bicoronal incision.  This generally yields acceptable results but with occasional abnormal skull reossification and residual calvarial defects.  A total cranial vault reconstruction is performed usually between 6-12 months of age also through a bicoronal incision.  When the metopic or coronal suture is involved, a fronto-orbital advancement with forehead reshaping is performed, generally between 6-12 months of age.  These later procedures are quite involved lasting up to six hours, often requiring blood transfusions due to significant blood volume loss of 25-400%, lengthy ICU (1-4 days) and hospital stays (up to 7 days).

Endoscopic-assisted strip craniectomy for the treatment of sagittal craniosynostosis was first described by D.F. Jimenez and C. Barone.  As their experience increased, they expanded the technique to treat the other forms of craniosynostosis.  With this technique, the prematurely fused suture is resected between 1-5 months. The infant is then placed in a custom made molding helmet the fifth day after surgery, usually until one year of age.  Once the fused suture is released, the brain grows exponentially during the first six months, expanding the skull to fit into the normocephalic shape of the helmet.  In other words, the helmet guides the final shape.  The procedure is performed through two 3.5 centimeter incisions, one placed posterior to the anterior fontanelle and one just anterior to the lambda.  The endoscope is used to assist in dissecting the dura from the undersurface of the fused suture. The fused suture is then resected and barrel-stave osteotomies performed.

The use of endoscopic-assisted strip craniectomy has been shown to a safe, effective  and expedient technique for the management of craniosynostosis.  The average length of stay is 1.01 days.  The average surgical time is 54 minutes.  Blood is transfused  in 9.7% of cases.  This also translates into significant savings in terms of hospital charges.  The majority of the patients are reported to be normocephalic based on anthropometric and photographic data.  Moreover, there is only two small scars rather than a bicoronal scar and the overall smoothness and contour approaches that of normal children.  In order to achieve optimal results through endoscopic-assisted strip craniectomy, early diagnosis and prompt referral is of utmost importance.