Bilateral meningoencephaloceles with cerebrospinal fluid rhinorrhea after facial advancement in the Crouzon syndrome.

Cerebrospinal fluid (CSF) leakage is a well-documented complication of traumatic, neurologic, and iatrogenic events. It occurs through a pathologic channel between the subarachnoid space and the floor of the cranium, most commonly as CSF rhinorrhea. Although the Roman philosopher and physician, Galen, in second century C.E., first incorrectly identified CSF rhinorrhea as a normal, physiologic phenomenon, its importance as a vehicle for central nervous system infection and as an indication of an underlying intracranial pathology has since been realized. In fact, it has been suggested that the overall risk of meningitis in the setting of persistent CSF rhinorrhea is 19%.1 Individuals with craniofacial dysostoses (CD), such as Crouzon and Apert syndromes, represent a unique subset of patients with a congenital predisposition for CSF leaks. The craniomaxillofacial surgical corrections that these patients undergo place them at additional iatrogenic risk of developing CSF leaks and meningoencephaloceles. Crouzon syndrome is an autosomal dominant syndrome associated with mutations in the gene encoding of the fibroblast growth factor receptor 2 on chromosome 10. The syndrome is characterized by a triad of premature craniosynostosis, exophthalmos, and midface hypoplasia, and is implicated in 4.8% of all cases of craniosynostosis. Importantly, it has been suggested that 63% of individuals affected by Crouzon syndrome have elevated intracranial pressure (ICP).2 Intracranial venous congestion, hydrocephalus, and obstructive sleep apnea are all potential complications of Crouzon syndrome that may contribute to elevations in ICP.3 It has been proposed that persistent intracranial hypertension contributes to the inferior displacement of the cribriform plates and thinning of the anterior cranial base in these patients, which may eventually facilitate the passage of CSF, meninges, and brain parenchyma into the paranasal sinuses.4 Le Fort III midface advancements are often used to address the ramifications of midface hypoplasia, including obstructed nasal airway, exorbitism, and impaired mastication. The procedure involves osteotomies made through the frontozygomatic suture, floor of the orbit, and the nasion; midline separation of the ethmoid from the anterior cranial base; and subsequent advancement of the resulting segment.3 In patients with Crouzon syndrome, high-level nasofrontoethmoidal osteotomy has been associated with tearing of the anterior cranial base dura, CSF leakage, and parenchymal herniation.4 Ridgway et al.4 studied 31 patients with eponymous craniosynostoses who underwent Le Fort III procedures; 11 of them had confirmed depressions of the anterior skull base, including two patients (6.5%) who presented with postoperative CSF rhinorrhea. One additional patient, who demonstrated both anterior skull base depression and bilateral flattening of the fovea ethmoidalis, developed a meningoencephalocele. None of the patients included in the study with radiographically confirmed normal morphology of the anterior cranial fossa experienced CSF leakage. Other documented complications of Le Fort III osteotomies in patients with CDs include lethal subarachnoid hemorrhage, which results from a transverse skull base fracture of the middle cranial fossa (Crouzon syndrome); internal carotid artery dissection (Apert syndrome); and carotid-cavernous sinus fistulas, which result in blindness.5 Akita et al.5 propose that, similar to CSF rhinorrhea, these untoward effects may be averted by preventing high-level craniofacial fractures. In 1926, Zweig6 reported the first intracranial repair of CSF rhinorrhea via a frontal craniotomy. Since then, extracranial and endoscopic approaches have evolved. Various studies have corroborated the low complication and recurrence rates of minimally invasive endoscopic repair. One study that examined 166 endoscopic CSF leak repairs, with a mean of 21 months of follow-up, found an overall success rate of 98% and an initial success rate of 91%.7 Factors such as morbid obesity, impaired wound healing, and an inability to visualize the dural defect endoscopically increase the chance of leak recurrence. Basu et al.8 emphasize that endoscopic repair failures are more likely in cases of leaks secondary to skull base tumor resections accomplished by craniotomy, noting the particular difficulty of endoscopic leak visualization. Notably, elevated ICP after the first attempted endoscopic repair has been associated with leak relapse in as many as seven of eight repair failures by one retrospective study.9 For this reason, some surgeons10 have advocated for placement of lumbar drains when addressing recurrent CSF leaks. However, the collective literature does not definitively establish the efficacy of lumbar drains in reducing the incidence of leak recurrence. In any event, it is important to consider the possibility of endoscopic repair failure and the value of alternative repair methods in cases of refractory CSF rhinorrhea. Case Summary We present the case of a 19-year-old African American woman with Crouzon syndrome and Graves disease. In 2011, she underwent a subcranial Le Fort III midface osteotomy and advancement to address issues related to her midface hypoplasia, including nasal obstruction, exorbitism, and malocclusion. The procedure was performed without any immediate postoperative complications. However, within a year of this procedure, the patient developed near-constant clear rhinorrhea and frequent sinus pain and pressure. She was referred to our department for consideration of endoscopic orbital decompression due to her exophthalmos secondary to Graves disease. Rigid nasal endoscopy demonstrated large intranasal pulsatile masses that were concerning for bilateral ethmoid encephaloceles (Fig. 1A). A computed tomography (CT) of the sinuses revealed multisinus opacification and bilateral soft-tissue masses that extended into the nasal cavities through bony defects overlying her ethmoid sinuses (Fig. 2). A CT from 2009, performed before the Le Fort III osteotomy, showed an intact skull base without evidence of an intranasal mass or sinusitis. Figure 1. Ethmoid encephaloceles in the left nasal cavity. (A) Nasal endoscopy, showing intranasal masses extending through the middle meatus at initial presentation. (B) Recurrent encephalocele after failed endonasal repair. Figure 2. Ethmoid encephaloceles after facial advancement surgery. Orbital CT, showing bilateral soft-tissue masses extending into the nasal cavities through skull base defects overlying the patient's ethmoid sinuses. Several months after the diagnosis, our patient underwent endonasal resection of bilateral encephaloceles with anterior skull base reconstruction by using an underlay graft with nasal septal bone and inferior turbinate-free mucosa grafts. Tissue sealants and appropriate collagen- and gelatin-based materials were used as adjuvant packing materials. The patient had no immediate complications after surgery and no clinical evidence of CSF leak at her 3-week postoperative visit. However, within 6 months of her initial repair, she did note intermittent clear rhinorrhea and occasional headaches, although no definitive signs of CSF leak were ever noted on surveillance examinations. Unfortunately, our patient developed new-onset seizures presumed to be secondary to infectious meningitis, although a workup was inconclusive. Of note, multiple diagnostic lumbar punctures during this episode failed to reveal evidence of increased ICP. In fact, no CTs collected at any point in our patient's care showed signs of elevated ICP. Nasal endoscopy around this time revealed a dehiscence of the anterior skull base repair site with recurrent encephalocele and CSF rhinorrhea (Fig. 1 B). In preparation for her revision surgery, a lumbar drain with intraoperative fluorescein solution injection was used. Fluorescein was noted to be actively draining from both the left and right skull base repair sites. In addition, there was endoscopic evidence of a recurrent right-sided encephalocele. The decision was made to proceed in a staged manner by addressing the left side initially with a posterior-based nasoseptal flap and delayed repair of the right side. After encephalocele resection, the left skull base was repaired with an underlay graft of cadaveric skin and septal cartilage with vascularized flap coverage. On the right side, the recurrent encephalocele was resected and the skull base defect was temporized with a cadaveric skin graft, tissue sealant, and standard packing materials. The patient had no immediate or delayed complications after this surgery. Several months later, the patient once again developed symptoms of CSF rhinorrhea and recurrence of right encephalocele. The patient ultimately underwent open repair with a pericranial flap with a calvarial bone graft used for definitive anterior skull base repair (Fig. 3). Importantly, an extraventricular drain was placed intraoperatively and was kept in place during her entire inpatient stay. It was discontinued before discharge. To date, the patient remains asymptomatic, without clinical or endoscopic evidence of encephalocele or CSF leak recurrence. Figure 3. Intact skull base after transcranial repair. CT of the head, showing repair of anterior skull base with bilateral calvarial bone grafts in place.