Association between Lateral Skull Base Thickness and Surgical Outcomes in Spontaneous CSF Otorrhea

Abstract

Objectives (1) Correlate skull base thickness with perioperative outcomes for spontaneous cerebrospinal fluid (CSF) otorrhea. (2) Augment perioperative counseling of patients with abnormally thin skull bases. Study Design Case series with chart review. Setting Tertiary center. Patients with spontaneous CSF otorrhea have thin skull bases. This is associated with obesity and/or idiopathic intracranial hypertension. The influence of skull base thinning on perioperative outcomes is unknown. Subjects and Methods A retrospective review was conducted from 2004 to 2014. Forty-eight cases of spontaneous CSF otorrhea met the inclusion criteria of primary surgery by the senior authors: preoperative dedicated temporal bone computed tomography, absence of other leak etiologies, and follow-up >6 months. Patients were stratified into thin (<0.9 mm) and thick (>0.9 mm) groups based on computed tomography measures of their tegmen. Primary outcomes measures were as follows: postoperative meningitis, recurrent leak, second site leak (contralateral ear/anterior fossa), and permanent shunt placement. Hearing outcomes were not assessed in this study. Results Thirty and 15 patients composed the thin and thick groups, respectively. Both the incidence ( P < .0001) and the rate ( P = .005) of adverse outcomes were significantly higher in the thin group. Only 2 patients in the thick group experienced an adverse outcome. Eleven patients underwent multiple procedures for spontaneous leaks. The recurrence rate was 14.5%. All but 1 recurrence occurred in the thin group. Conclusions An abnormally thin tegmen was significantly associated with adverse perioperative outcomes in cases of spontaneous CSF otorrhea. A thick skull base and the presence of an encephalocele may be protective against recurrence. The effect of untreated intracranial hypertension on the results is unknown.