Endoscope-Assisted "Extended" Suturectomy for Unicoronal Craniosynostosis: A Technical Note.

Abstract

Since the initial description of endoscopically assisted suture craniectomy followed by orthotic helmet therapy by Barone and Jimenez,1 many craniofacial teams have shown acceptance of this technique, including our center.2,3 The original technique described by Jimenez and Barone4 for unicoronal craniosynostosis involved a 2-cm incision on the scalp midway between the anterior fontanelle and pterion, followed by endoscopically assisted removal of a 5-mm sleeve of fused coronal suture between the above two points. They also mention removal of the bone at the wing of sphenoid during the suturectomy over the medial frontosphenoid suture region to liberate the orbit. We have, in principle, adopted the above technique in our practice, but have noted some difficulty in locating the pterion accurately as a part of the lateral dissection. The extent of medial dissection is straightforward, mainly because of the presence of the anterior fontanelle. The pterion, on the other hand, is typically pulled toward the superolateral angle of the orbit and vice versa as a part of the deformity described in unicoronal craniosynostosis. We believe that a fused frontosphenoidal suture in addition to the fused coronal suture is the reason for this phenomenon (Fig. 1). An interesting study by Rogers and Mulliken5 revealed that in 36 of 51 computed tomographic scans of unicoronal synostosis patients, there were additional sutures involved in the basilar coronal ring. More specifically, they demonstrated synostosis of the lateral 50 percent of the frontosphenoidal suture, extending to the middle orbital roof in 25 to 75 percent of cases. This feature was progressive as the age of the baby increased from 3 to 5 months old and almost total by 5 months of age.Fig. 1.: Comparison of the location of the pterion on the affected and unaffected sides (black arrows) in a 4-month-old girl with right unicoronal craniosynostosis. The pterion is pulled toward the superolateral orbit. Also, note the fused frontosphenoidal suture on the right side (blue arrow) compared to the patent frontosphenoidal suture on the unaffected left side (green arrow).Our endeavor is to operate on the child as soon as possible (i.e., within 3 months of age), but our cohort has more than half the number of cases in the age group of 3 to 5 months. Hence, it is our practice to extend the suturectomy along the lateral frontosphenoidal suture, all the way up to the superolateral angle of the orbit (also including the frontozygomatic suture in the process). This gives us a buffer to counter the restrictive force of the frontosphenoidal suture fusion happening between 3 to 5 months of age and also spares us the obligation to find the pterion accurately. The dissection proceeds behind the ridge of the sphenoid wing and then turns anteriorly to include the frontosphenoidal suture and frontozygomatic suture (Fig. 2), in the process truly liberating the orbit. We think this is a practically simpler endpoint compared to the pterion at the level of the lateral canthus, as described by the pioneers.Fig. 2.: Postoperative scan demonstrating the “extended” suturectomy to include the frontosphenoidal suture up to the superolateral orbital margin.The impact of this modification (“extended” suturectomy) on the eventual outcome should be validated by long-term follow-up studies. We recommend this simple technical refinement of extending the suturectomy until the superolateral orbit to any surgeon adopting the minimally invasive methods (orthotics or springs) of craniosynostosis correction. DISCLOSURE None of the authors has a financial interest in any of the products or devices mentioned in this article.