Endoscopic and Open Resection of Sphenoid Sinus Meningoencephaloceles with Repair of Skull Base Defects

Objective: To describe the diagnosis, resection, and repair of 11 sphenoid meningoencephaloceles through combined endoscopic and open techniques.

Background: Encephaloceles can be congenital, traumatic, or erosive/spontaneous in origin. Sphenoid sinus encephaloceles are the rarest and are most commonly present with CSF rhinorrhea. They may also present with meningitis, sinusitis, or pneumocephalus. Increasingly, endoscopic instruments and techniques have been used to diagnose, resect, and reconstruct skull base defects, obviating the need for craniotomy. A transnasal endoscopic approach may be sufficient, but in extensive encephaloceles with large lateral components, endoscopic techniques are combined with an open transmaxillary approach.

Methods: Patients symptomatic for CSF rhinorrhea had nasal fluid collected and sent for β-2 transferrin analysis. MRI and CT scans with contrast were obtained allowing real-time image guidance intraoperatively. Patients had a lumbar drain placed. Intrathecal fluorescein was used in five patients to help identify the site of the skull base defect, presence of a CSF leak at the end of the procedure, and the adequacy of closure. All patients underwent a transnasal endoscopic approach with entry into the sphenoid sinus and identification of the origin of the encephalocele. Encephaloceles with far lateral extension required a combined open transpterygoid approach through the maxillary sinus face and posterior wall. Despite far lateral extension in several cases, none of the patients required a lateral skull base approach. Lumbar drains placed for 3-5 days decrease pressure on the encephalocele skull base origin/CSF leak repair site. When the skull base defect is large, and there is risk of pneumocephalus, nasopharyngeal tubes are placed from the anterior nose to just past the free margin of the soft palate to break the air seal and prevent positive pressure from developing in the pharynx with resultant pneumocephalus when the patient coughs or sneezes in the immediate postoperative period.

Results: We included 11 patients ranging in age from 33 to 75 years (mean, 49 years). Nine patients were women and obese, with BMIs greater than 30 kg/m². Mean follow-up was 6.2 months (range, 1-25 months). In all 11 cases, we were able to obtain complete encephalocele exposure and resection, including those with far lateral extension by either transnasal endoscopic techniques alone or combined transnasal endoscopic and open endoscopic-assisted transmaxillary approaches. None of our patients required a lateral skull base approach, thus avoiding the associated morbidity of a craniotomy. All patients had complete resolution of their CSF leaks postoperatively.

Conclusion: Meningoencephaloceles of the sphenoid sinus are rare and present a diagnostic and operative challenge to skull base surgeons. Endoscopic telescopes greatly assist in resection and repair of skull base defects. Image guidance permits precise localization and safe resection of these lesions at their skull base/brain origin. Transnasal endoscopic techniques alone or in conjunction with an endoscopic-assisted transmaxillary approach can be used to resect these lesions, even those with far lateral extension. A combination of abdominal fat, fibrin sealant, and local vascularized middle turbinate flaps can be positioned in the defect to create a watertight closure.