Middle Cranial Fossa Encephalocele and Cerebrospinal Fluid Leakage: Etiology, Approach, Outcomes

Objective: The goal of this study is to compare outcome data for surgical approaches used in the management of a middle cranial fossa encephalocele or cerebrospinal fluid (CSF) leak and, secondarily, to evaluate the role of obesity and the etiology of the defect. Study Design: Retrospective chart review. Methods: Patients who underwent surgical repair of middle cranial fossa tegmen defects between January 2009 and July 2015 were eligible for inclusion. Demographics, surgical approach & technique, audiological outcomes, and need for revision surgery were documented. Results: Seventy-five patients were included, 2 of which underwent bilateral repair. The male to female ratio was 1:3, the mean age was 52.3 years, the mean BMI was 34, and the left side was involved in 53.3% of cases. Fifty-one cases were spontaneous in origin, 2 iatrogenic, and 22 were due to chronic otitis media. Eighteen underwent middle fossa craniotomy, 30 underwent a transmastoid approach for repair, and 27 underwent a combined approach. A post-operative CSF leak was seen in 6 patients. Five required revision surgery and one patient was managed conservatively. Three out of the five had previously undergone a combined approach, ⅕ a transmastoid approach, and ⅕ a middle fossa craniotomy. Conclusions: The most common etiology for middle cranial fossa tegmen defects is no longer iatrogenic, but spontaneous, and it is most commonly seen in obese females. The traditional middle cranial fossa approach for repair is not required in all cases, but should be employed in anterior or multiple defects. The transmastoid approach with hydroxyapatite reconstruction may be considered for small defects limited to the tegmen mastoideum. Level of Evidence: III