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.
Incision
A small area of hair is clipped posterior to the stephanion for placement of the incision ( Fig. 9.8 ). The overall exposure and tissue dissection is relatively small and narrow, thus requiring only a single small incision. To minimize blood loss, a needle-tip Bovie unit is used to cut the dermis on the cut mode at 15 watts ( Fig. 9.9 ). Rapid movement minimizes scarring and epidermal burn. Once epidermis is incised, deeper dissection is done with the needle tip on coagulation mode. The incision is typically 1.5 to 2 cm in length. As described in Chapter 4 , the subgaleal dissection is begun on either side with the aid of an endoscopic lighted retractor.
Procedure
Subgaleal dissection is first directed towards the anterior fontanelle using the monopolar and lighted retractor ( Fig. 9.10 ). An endoscope can then be passed under the galea to visualize the anterior fontanelle from above ( Fig. 9.11 ). The subgaleal dissection is then directed towards the area of the pterion. Full release can then be accomplished by gently passing an insulated brain ribbon over the galea to reach the pterion ( Fig. 9.12 ). The needle tip is once again used to elevate the scalp from the pericranium and temporalis muscle fascia. The rhinoplasty lighted retractor is very useful for direct visualization or with the zero-degree endoscope. The dissecting plane is developed to an area 1 or 2 cm anterior to the ear and behind the pterion ( Fig. 9.13 ). The option of dissecting the temporalis muscle from the underlying bone can be done under direct visualization and with the aid of a #1 Penfield dissector. This maneuver elevates the temporalis off the bone so that the osteotomy can be done without cutting into the muscle fibers ( Fig. 9.14 ). However, even when these fibers are cut along their longitudinal axis, we have found no negative residual effect after the surgery or subsequent to it.
Osteotomy
At the beginning of our series, we theorized that resection of the entire stenosed suture was necessary for a successful outcome. The procedure included placing the incision directly over the suture and resecting both medial and lateral extensions. We made modifications to include making a lateral frontal osteotomy over the orbital area, resecting parts of the greater wing of the sphenoid bone, and osteotomizing the sphenofrontal suture. These maneuvers led to unwanted and unnecessary blood loss (albeit still small enough not to need transfusion). Seeing no significant improvement to our earlier excellent results, we decided to return to a more minimalistic approach. A decision was made not to necessarily resect the actual suture but instead to create an entire new osteotomy and extend it posterior to the pterion ( Fig. 9.15 ). The osteotomy width need not be greater than 4 or 5 mm as the growing brain will widen the osteotomy over time. Absolute care must be taken to assure that the osteotomy reaches the squamosal suture. Failure to do so leaves a band of bone connecting and attaching the frontal and temporal bones. This bony connection prevents the forward movement of the fronto-orbital complex and deformity correction. When doing consultation for other center’s failures, invariably it can be seen in the postoperative computed tomography (CT) scans that complete release was not done by the operating surgeons ( Fig. 9.16 ). The osteotomy is begun with a small burr hole using a 7-mm pediatric craniotome directly at the incision site. The round end of a #1 Penfield dissector is used to gently free the dura from the bone towards the anterior fontanelle ( Fig. 9.17 ). The Penfield dissector is advanced to the edge of the fontanelle, which is palpated with the nondominant hand over the scalp. The osteotomy can be done with the Mayo scissors or rongeurs ( Fig. 9.18 ). Endoscopic visualization of the bony-dura interface is useful and can help minimize complications such as dural tears. The endoscope (30-degree) also allows the surgeon to directly see the fibers of the anterior fontanelle ( Fig. 9.19 ) assuring total medial release of the frontal and parietal bones ( Fig. 9.20 ). Once the medial release has been achieved, bony hemostasis is done with the suction electrocautery unit and Surgiflo. Attention is then paid to dissection of the epidural plane between the burr hole and the squamosal suture. The burr hole is enlarged longitudinally with 5-mm Kerrison rongeurs for a distance of 1 or 2 cm. This bony enlargement allows the insertion of a 30-degree endoscope under the bone, which is then advanced towards the ear ( Fig. 9.21 ). The endoscope and small suction are passed in tandem and the dura is separated from the bone. Sweeping motion movements allow for visualization of the frontal dura, the greater wing of the sphenoid bone ( Fig. 9.22 ), and the point where the closed coronal suture opens as it nears the pterion ( Fig. 9.23 ). Further epidural dissection is then undertaken posterior inferiorly towards the squamosal suture ( Fig. 9.24 ). Once the squamosal suture is reached, all of the room lights are shut down and the endoscope tip is trans-illuminated and marked with a skin marker. This mark is useful in knowing the location of the suture and direction of the osteotomy ( Fig. 9.25 ). The osteotomy is then done with bony removal using the bone cutting rongeurs until the squamosal suture is reached ( Fig. 9.26 ). Osseous hemostasis of the area around the squamosal suture is accomplished by placing an insulated 7-French (small) suction and delivering the coagulating energy with the suction cautery unit set at 60 watts. The connection is made at the base of the suction ( Fig. 9.27 ) and the energy carefully delivered to the osteotomy site. Utmost care is taken to prevent cauterization of either the scalp above or the dura below. Another reason to make the osteotomy at a different location than the coronal suture itself, is that it is not uncommon for the stenosed suture to have a deep bony ridge that extends deep and indents the underlying dura ( Fig. 9.28 ). If care is not taken and the cut is made directly on this type of suture, the risk of a dural tear increases significantly. The osteotomy is made with bone rongeurs and taken all the way down to the squamosal suture ( Fig. 9.29 ). After adequately cauterizing the area around the squamosal suture, the rest of the bone can be cauterized with the suction cautery unit. The head is placed in the Trendelenburg position and the surgical field is copiously irrigated with normal saline to remove any remaining debris. The surgical field is inspected with the endoscope to look for any remaining bleeders. A Valsalva maneuver checks for cerebrospinal fluid leaks. If all is well, Surgiflo is generously placed in the surgical site. The skin is infiltrated with bupivacaine 0.25% and epinephrine 1:250,000 at 1 cc/kg. The galea is closed with 4-0 monocryl and the dermis with Mastisol and Steri-strips. Prior to extubation, a postoperative hemoglobin and hematocrit is obtained, as well as an anteroposterior (AP) and lateral skull radiograph ( Fig. 9.30 ). Following extubation, the patient is transferred to the postanesthesia care unit and then to the pediatric intensive care unit. Discharge from the hospital takes place the following morning.
