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Unicoronal Craniosynostosis
Introduction
Unilateral nonsyndromic coronal craniosynostosis is a challenging condition for the treating surgical team given all of the deformational changes associated with this condition. Unlike other single suture closures, unicoronal stenosis leads to a combination of skull base, calvarial, and facial deformities. It is a well-known fact that the phenotypic presentation includes the following prominent features: (1) ipsilateral vertical dystopia ( Fig. 9.1 ); (2) ipsilateral proptosis ( Fig. 9.2 ); (3) ipsilateral frontal plagiocephaly ( Fig. 9.3 ); (4) contralateral nasal tip deviation ( Fig. 9.4 ); (5) ipsilateral exotropia ( Fig. 9.5 ); (6) cranial scoliosis ( Fig. 9.6 ); and (7) strabismus. As the patients get older, correction of all of these deformities becomes increasingly more difficult to do. Consequently, the sooner that the problem is addressed, the sooner the correction can take place. As stated in a previous Chapter 3 , the timing of surgical intervention has been an issue of debate amongst treating surgeons for several decades. The balance of operating early or ultra-early needs to be balanced with the significant detrimental effects of a large and complex surgery on a young infant. The traditional approach to these cases is to proceed with bifrontal craniotomies, orbital frontal bandeau advancement, and forward movement of the affected side (fronto-orbital advancement [FOA]). The recommendation is to wait until the patient is 9 to 12 months of age. By then the orbital, nasal, and skull base deformities are fully set in and nearly impossible to correct, particularly the vertical dystopia. Literature analysis supports the fact that FOA is not really successful in correcting astigmatism, strabismus, or amblyopia and in cases, can aggravate the condition iatrogenically. Furthermore, it is commonly found in surgical reports that there is relapse of the frontal bar, frontal craniotomies, and temporal hollowing. This fact has been clearly and elegantly shown by McCarthy in his long-term outcome reports presented in the plastic surgery literature. Given our success treating sagittal synostosis with endoscopic-assisted, minimally invasive surgery, we began to modify and develop techniques to release the stenosed suture at an extra early age with the goal of allowing the brain to grow along normal vector forces and correct the aforementioned deformities. As originally theorized, we were very pleasantly surprised to see the rapid correction of the congenitally related malformations. Of utmost importance is the rebalancing of the dystopia associated with coronal closure. We noticed that as the brain continued to grow along genetically predetermined vector lines following sutural release, the entire bony orbital complex began to move inferiorly and anteriorly. This eventually led to eye realignment along the horizontal axis, thereby correcting the vertical dystopia. Also evident was the slow but continued realignment of the deviated nasal bone to the midline. As the orbit repositioned in normal place, the exotropia and strabismus also corrected. More details on this correction are provided in the ophthalmic Chapter 7 . The last deformity to typically correct is the ipsilateral frontal plagiocephaly. This chapter will detail the techniques for performing this procedural release in young infants.
Positioning
Following endotracheal intubation and placement of the intravenous lines, a precordial doppler is secured on the patient’s chest. The table is then turned 180 degrees away from the anesthesia team and the patient’s head is placed in a neutral position on a pediatric horseshoe head holder. Disposable corneal protectors are carefully placed in each eye using abundant amounts of an ophthalmic lubricating ointment. The head is then turned about 15 degrees to the contralateral side of the synostosis and the entire surgical field is draped in standard fashion ( Fig. 9.7 ). The stephanion (superior temporal line and coronal suture junction) on the affected side is identified and the entire face, including eyes and nose, are prepped with povidone-iodine scrub and paint solutions and appropriately allowed to dry for maximum effectiveness. A Mayo stand is placed over the patient with all of the needed instrumentation as shown in Chapter 4 . Antibiotics should be given intravenously 30 minutes prior to making the skin incision and a complete time out should be done as well.
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