CHAPTER 184 Endoscopic Treatment of Craniosynostosis

Definitive treatment of infants with craniosynostosis continues to be surgical in nature. The ultimate corrective goal remains achievement of proper cranial and facial anatomic relationships and normalization of overall craniofacial morphology. As described in previous chapters, many procedures have been devised in modern times since Lannalogue introduced strip craniectomies in 1890.¹ These procedures have ranged from simple suturectomies and strip craniectomies^1,2 to very extensive surgical procedures after the development of craniofacial surgery as a distinct surgical discipline in the 1970s.^3–9 Surgical treatment of sagittal synostosis has varied from linear craniectomies to extensive calvarial vault remodeling.^9–15 Management of metopic synostosis has also varied from linear craniectomies to standard bifrontal craniotomies and orbitofrontal advancement and forehead recontouring.^16–26 Likewise, coronal synostosis has been treated with simple suturectomies, unilateral canthal advancements, or bifrontal craniotomies and forehead recontouring.^6,27–43 Finally, lambdoid synostosis is most commonly treated with occipital craniectomies and some sort of occipital reconstructive technique.^44–49

Because of the inconsistent nature of long-term results and the significant trauma associated with these operations, we began to develop and use minimally invasive, endoscopically assisted techniques to treat infants with craniosynostosis more than a decade ago.^{10,15,47–54} The underlying principles of our approach include (1) operating on very young infants (preferably 3 months of age or younger), (2) using the very rapid brain growth that occurs in this age group, (3) allowing brain growth to correct the presurgical deformities, and (4) applying postoperative helmets to aid in and achieve correction and normalization of craniofacial asymmetry. Our original goal was to perform a very simple and rapid operation to halt progressive craniofacial deformation and later perform a definitive procedure on a less severe deformity. However, our early results demonstrated excellent and persistent correction, and thus we began to use these procedures as definitive treatment. Presented in this chapter are the techniques and results of our protocols for treating patients with craniosynostosis by successfully using minimally invasive endoscopic techniques.

Instrumentation

Surgical

Although a comprehensive surgical tray is currently being developed and will soon be available (Karl Storz Endoskope, Tuttlingen, Germany), these procedures can be performed with a relatively simple tray of instruments that are readily available in most operating rooms. The endoscopic equipment consists of two rigid rod lens endoscopes. A 30-degree angled scope is used to visualize and separate the dura from the overlying stenosed suture and skull. A 0-degree angled endoscope is used to view the dura and bone during coagulation and hemostasis of these two structures (Fig. 184-1). Flexible and fiberoptic scopes are not used because of the lower image resolution that they provide. Standard three-chip cameras and high-definition monitors provide superb visualization of the surgical field. Additional visualization and exposure can be obtained with the use of a rhinoplasty lighted retractor. The retractor connected to a standard light source can be used to elevate the scalp while developing the dissection plane between the galea and pericranium. Bloodless dissection is undertaken with the use of monopolar electrocautery and the needle tip set at 15 W, blend 1 (Valley Lab, Valley Forge, PA). Insulated handheld malleable retractors are used to protect the dura and galea during dissection of the subgaleal plane and coagulation of the diploë after osteotomy and bone resection. To minimize intraoperative and postoperative blood loss from the diploë after the osteotomies are performed, a disposable suction electrocautery handpiece (Valley Lab, Valley Forge, PA) is used and set at 60 W. The malleable tip can be adjusted to reach the desired areas for further coagulation, and final hemostasis is achieved with Surgiflo (Johnson & Johnson, Cincinnati, OH) and liquid thrombin (GenTrac, Inc., Middleton, WI) and Gelfoam (Pfizer, New York). In most patients the osteotomies can be made with a pair of sharp curved Mayo scissors, but when the bone is thick (older patients), bone-cutting scissors can be used. When removing the bone in piecemeal fashion (metopic or coronal), curved bone rongeurs (DePuy Spine, Raynham, MA) or side-biting rongeurs (Jansen Middleton, C-Med Surgical, Pompton Lakes, NJ) can be used to resect the bone near the skull base. When treating a patient with significant trigonocephaly, the sharp bony edges of the osteotomies can be contoured with an electric rasp (Stryker, Kalamazoo, MI). Scalp closure is achieved with 4-0 Monocryl (Ethicon, Cincinnati, OH), and Dermabond is used for final skin closure. Of note, no drains are left in place, and Foley catheters, central lines, and arterial lines are not routinely used during any of these procedures.

FIGURE 184-1 Intraoperative photograph of a patient undergoing endoscopic treatment of sagittal synostosis. A 30-degree endoscope is inserted through the anterior incision and used to visualize the osseous-dura interface. An insulated malleable retractor is placed through the posterior incision to protect the dura during cauterization of the osteotomies.

Helmet

The use of helmets, albeit time- and effort-consuming, plays a critical role in achieving excellent results after the osteotomies and cranial release. Typically, on the third postoperative day the patient’s head is scanned with a proprietary infrared beam Star scanner (Orthomerica Products, Inc., Orlando, FL), and a custom-made helmet is manufactured and delivered on the fifth postoperative day. The helmets are manufactured with the commercially available resin Surlyn (Dupont, Wilmington, DE), which is a thermoplastic ionomer resin and is the random copolymer poly(ethylene-co-methacrylic acid). Its physical properties make it an ideal material for molding cranial helmets. The overall helmet shell is made of Surlyn and the inner padding is made of an ethylene acetate lining and Reston foam stabilizer pads (3M, St. Paul, MN). To standardize the manufacturing process, the patient’s head is scanned locally and the digital data sent to a central manufacturing center (Orlando, FL), where a computer-assisted process allows the creation of a custom-made helmet set to the practitioner’s specifications. The overall goal of the helmets is to assist the brain in reshaping the deformed cranium by allowing cranial expansion in recessed areas and compression in areas of overcompensated growth (Figs. 184-2 and 184-3). These helmets do not restrict cranial growth but rather redirect it, as evidenced by normal progression of head circumference growth. The younger the child, the more helmets will be worn, with up to three helmets usually required to complete treatment and the duration of treatment ranging between 6 months and 1 year. Parents can be reassured that the prosthetics are well tolerated.

FIGURE 184-2 Cross-sectional diagram of right coronal synostosis after an endoscopic suturectomy is performed. Postoperatively, the helmet is used to place compressive force (red arrows) over the areas of overcompensated growth. Recessed areas are allowed to expand (yellow arrows) to achieve normalization of cranial vault shape.

FIGURE 184-3 Postoperative helmet therapy for sagittal synostosis prevents further anteroposterior elongation (red arrows) while allowing expansion of the temporal and parietal areas (yellow arrows) and normalization of the cephalic index.

Sagittal

Surgical Procedure

Patients are placed in the modified prone position (sphinx) in a viscoelastic pad. Two incisions are made across the midline, each measuring about 3 cm. The first incision is located approximately 2 to 3 cm behind the anterior fontanelle and the second incision is placed immediately in front of the lambda. The scalp incision is taken through the galea aponeurotica but with preservation of the pericranium. After applying insulated scalp retractors, a needle-tipped monopolar cautery is used to develop the subgaleal plane in a bloodless fashion from the anterior fontanelle to the lambda and about 3 cm from the midline bilaterally. A pediatric craniotome is used to make a bur hole at the edge of each incision. Once the dura is freed from the midline bone with a No. 1 Penfield dissector, a 6-mm osteotomy is made at each incision with 6-mm Kerrison rongeurs. The bone is dissected anteriorly toward the anterior fontanelle and then cut with Mayo scissors in a triangular shape. A 30-degree rigid endoscope is inserted under the bone at the anterior incision and advanced posteriorly toward the lambda with the aid of a 10 French suction tip. Suction is used to dissect, as well as keep the endoscopic field dry and free of blood. A second posterior osteotomy is made at the lambda in similar fashion. Once the dura has been freed from the overlying bone, bone-cutting or Mayo scissors are used to make the lateral osteotomies. Hemostasis is achieved with a large piece of Gelfoam (Pfizer, New York) on the dura along with gentle pressure. Wedge (barrel stave) osteotomies are also created with scissors after the dura is freed from the bone directly behind the coronal suture and then directly in front of the lambdoid sutures (Fig. 184-4). The wounds are closed with absorbable 4-0 Monocryl sutures and Ethibond. The patient is observed overnight, and pain control is maintained with alternating acetaminophen and ibuprofen and intermittent intravenous morphine as needed. The majority of patients are discharged on the morning after surgery.

FIGURE 184-4 Artistic representation of the amount of bone resected for the treatment of sagittal synostosis with endoscopic techniques. A wide vertex craniectomy with bilateral barrel stave osteotomies is performed through two small scalp incisions.

Results

Approximately 200 consecutive patients have been treated over a period of 10+ years. Seventy-four percent were boys and 26% were girls. The mean and median ages at the time of surgery were 3.7 and 3.2 months, respectively. The length of the craniectomy varied between 4.5 and 13 cm, with a mean length of 10.5 cm. The width ranged between 1.5 and 7 cm, with a mean width of 5.4 cm. Two patients required intraoperative blood transfusion (1%), and 14 patients received postoperative blood transfusions (7.4%). The mean estimated blood loss was 27 mL with a range of 5 to 150 mL. All but 8 patients were discharged on the morning after surgery (96%). The mean surgical time was 57 minutes, with a range of 30 to 150 minutes. Postoperative swelling was minimal and confined to the scalp. The patients did not experience fever as is commonly seen with the traditional operations. Complications were minimal and included three small dural tears, which were repaired primarily without lasting effects; 5 patients experienced superficial scalp irritation, which was treated successfully by temporary (<1 week) removal of the helmet and local care. There were two deaths in the series. In both cases, the procedures went well and without long complications. During the postoperative period, massive hemolysis and diffuse cerebral ischemia developed in the first child. Systemic arterial and venous thrombosis of unknown etiology developed in the second child. In both cases, life support was withdrawn at the request of the parents. There were no infections, air embolism, seizures, postoperative hematomas, or need for conversion to an open procedure. Using a cephalic index (CI) of greater than 75 as the criterion for excellent results, 87% of the patients achieved excellent outcomes. A good result was classified as a final CI between 71 and 75. Eight percent of the patients had good results and 4.3% had poor results (CI <70) (Fig. 184-5).

FIGURE 184-5 Two-month-old boy with craniosynostosis. Preoperative photographs show marked frontal bossing and scaphocephaly. At 3 months postoperatively, the patient demonstrates significant correction that has been maintained up to the 6-year follow-up.

Coronal

Surgical Procedure

Access to the suture is gained through a 2- to 3-cm incision located behind the hairline at the level of the stephanion, and a subgaleal dissection plane is developed between the anterior fontanelle and the squamosal suture (Fig. 184-6). A 7-mm craniotome is used to make a bur hole, which is then enlarged to allow passage of the endoscopes under the bone. Once the dura is safely dissected away from the bone, a 6-mm osteotomy is made with a combination of Mayo scissors and bone rongeurs. The osteotomy extends from the anterior fontanelle to the squamosal suture behind the pterion (Fig. 184-7). Hemostasis is achieved as previously described and the incision closed with Monocryl and Dermabond.

FIGURE 184-6 Intraoperative photograph showing the location of the incision on a patient with left coronal synostosis. The endoscope is being directed toward the left squamosal suture while the suction tip is being used to dissect and keep the endoscopic field free of blood.

FIGURE 184-7 Diagram showing the extent of bone resection for the treatment of right coronal synostosis. The dark line represents the location and extent of the scalp incision. The osteotomy extends from the anterior fontanelle to the squamosal suture behind the stenosed suture and pterion. A 6-mm osteotomy suffices because frontal bone advancement will increase the size of the osteotomy over the subsequent months.

Results

The mean surgical time was 56 minutes. Ninety-seven percent of the infants were discharged the morning after surgery. Mean estimated blood loss was about 20 mL. Overall, the blood transfusion rate was about 1%. Correction of preoperative deformities occurs sequentially and in the following order: nasal deviation, vertical dystopia, sagittal imbalance, and finally, frontal plagiocephaly. Continued improvement is seen over the subsequent years (Fig. 184-8). Review of risk factors showed that no patients experienced infections, venous air embolism, or sagittal sinus injury. No mortality, postoperative hematomas, or visual or ocular injuries occurred. Two patients had small dural tears. A minor scalp irritation developed in one patient but resolved with local care.

FIGURE 184-8 A 2-month-old with severe right coronal synostosis exhibits frontal plagiocephaly, vertical dystopia, and nasal/midface deviation. Three years after endoscopic treatment, these deformities have been fully corrected and child has a normal appearance.

Metopic

Surgical Procedure

A small 2- to 3-cm incision is made behind the hairline and across the metopic suture. A rhinoplasty lighted retractor is used to develop the subgaleal plane from the anterior fontanelle to the nasofrontal suture. A bur hole is made with a 7-mm craniotome and enlarged with Kerrison rongeurs. A 30-degree endoscope is used to develop a plane of dissection between the dura and the overlying stenosed suture. Using scissors and bone rongeurs, a 6-mm osteotomy is made between the anterior fontanelle and the nasion (Fig. 184-9). Bridging veins from the sagittal sinus to the stenosed suture are often encountered and directly cauterized with bipolar forceps. After hemostasis, the incision is closed with Monocryl and Dermabond.

FIGURE 184-9 For the treatment of metopic synostosis, a small incision is made on the midline (dark line) behind the hairline and a 6-mm osteotomy is created that extends from the anterior fontanelle to the nasofrontal suture. Failure to reach this suture will lead to improper correction of hypotelorism and trigonocephaly.

Results

Mean estimated blood loss was about 40 mL, and the overall transfusion rate was about 8%. All patients were discharged the day after surgery. Mean surgical time was just under 1 hour. Like the sagittal and coronal cohorts, metopic patients do not experience postoperative pyrexia, irritability, or major facial swelling or bruising. No conversions to open procedures were necessary. Progressive correction of trigonocephaly has been seen in all our patients with forward advancement of the recessed frontal bones. Additionally, correction of hypotelorism was achieved in all cases and without the need for extensive bifrontal craniectomies, orbital repositioning, or ocular manipulation. As with the coronal group, continued improvement was noted with the passage of years after the original surgery (Fig. 184-10).

FIGURE 184-10 Patient with metopic synostosis. An anteroposterior preoperative view at 4 weeks of age shows a midline ridge and hypotelorism. A preoperative top view at 3 months of age shows marked progression of trigonocephaly. Six-year postoperative views demonstrate correction and normalization of these deformities.

Lambdoid

Surgical Procedure

The patient is placed on a cerebellar horseshoe with the head turned so that the ipsilateral stenosed suture is on the superior horizontal plane. The first incision is made immediately lateral to the lambda on the side of the stenosis, and the second incision is made medial to the asterion. Each incision is about 2 to 3 cm. A rhinoplasty lighted retractor or a 0-degree endoscope can be used to develop the subgaleal plane between the incisions. Two bur holes are made with a pediatric craniotome, each at an incision. The bur holes are enlarged with Kerrison rongeurs. A 30-degree endoscope is then inserted under the bone, along the stenosed suture, to help develop the epidural space. Once freed, the bone can be cut with Mayo or bone-cutting scissors. The osteotomy is about 5 to 8 mm in width (Fig. 184-11). After bone hemostasis is achieved, the skin is closed in a similar fashion as for the other sutures described earlier.

FIGURE 184-11 Diagram showing the location of the scalp incisions and the extent of bone resection (shaded area) for the treatment of right lambdoid synostosis.

Results

The cranial skull bone and calvarial deformities seen with lambdoid synostosis have been the most difficult to treat and correct with endoscopic techniques. Nevertheless, patients do show marked improvement, particularly those with moderate to mild deformities. However, even marked asymmetries can be corrected over time (Fig. 184-12). Blood loss is minimal with an average of 25 mL. No patient has needed blood transfusions, and mean surgical time was less than 1 hour. There have been no injuries to the transverse sinus or dura in the region of the lambda or asterion.

FIGURE 184-12 A 2-month-old boy with lambdoid synostosis has marked right occipital plagiocephaly and vertical misalignment of the ears. Four years postoperatively, these deformities show marked and significant improvement.