Temporal Meningoencephaloceles: Diagnostic Pitfalls, Surgical Repair, and Associated Pathologies

Objectives: We present our experience in the diagnosis and treatment of meningoencephaloceles of the temporal bone, specifically focusing on etiology, intraoperative findings, concomitant obesity, and recurrence rate.

Patients and Methods: We performed a retrospective chart review of all patients operated on for meningoencephaloceles of the lateral skull base in a tertiary referral center from 1999 to 2011. We included encephaloceles diagnosed preoperatively and the ones discovered incidentally intraoperatively. All imaging scans were retrospectively analyzed to try to correlate pertinent imaging details to intraoperative findings.

Results: There were a total of 35 patients, 22 females and 13 males. The average age was 51 years, ranging from 16 to 86 years. The meningoencephalocele was found on the right side in 16 patients and on the left in 17; 1 patient had bilateral disease. Clinical manifestations consisted primarily of clear otorrhea with associated conductive hearing loss. Other common symptoms included aural fullness, rhinorrhea, and headache. The distribution of the etiologies was: idiopathic (22), chronic otitis media or cholesteatoma (9), iatrogenic (2), and trauma-induced (2). The relationship between body mass index and spontaneous cerebrospinal fluid (CSF) leak was analyzed. The surgical repair of the meningoencephalocele was performed via a transmastoid approach in 17 cases, middle fossa approach in 1, and combined transmastoid/middle fossa approaches in 14; there were 3 cases where an anterior transpetrosal approach was added. The most frequent site of brain herniation was the tegmen tympani and/or mastoideum, but two cases involved the petrous apex and two others involved the sinodural angle. Recurrence was seen in four patients.

Conclusion: This is one of the largest series of meningoencephaloceles of the lateral skull base. They continue to present as diagnostic and treatment challenges for skull base surgeons. They may also be growing in importance due to an increase in the population of patients with obesity.