Characteristics of Patients undergoing Lateral Skull Base Repair for Cerebrospinal Fluid Leak

Introduction: Defects of the middle fossa floor can lead to cerebrospinal fluid (CSF) leak and result in headaches, decreased hearing, tinnitus and CSF egress from the nares or ear. Treatment is primarily surgical via middle cranial fossa (MCF) approach, mastoidectomy or combined approaches. Initial surgery fails in a small subset of patients, and we sought to characterize our patient cohort and identify risk factors requiring repeat surgery.

Methods: We retrospectively reviewed, under IRB approval, our institution’s neurosurgery database for adults with lateral skull base CSF leak surgical repair from January 2018 to August 2023.

Results: Our review yielded 33 patients, majority female (75.8%) with an average age of 58.7 years. Average preoperative BMI was 39 (range 23.8 – 61). Most common presentations included hearing loss (N=26, 78.8%), otorrhea (N=19, 57.6%), ear fullness (N=16, 48.5%), and headache (N=11, 33.3%). Symptoms were present for an average for 15 months. 27 patients (82%) had prior ear/skull base surgery including myringotomy, mastoidectomy, or combined myringotomy and tympanostomy. Two patients underwent placement of a ventriculoperitoneal shunt (VPS) during repair due to pre-existing IIH.

Intraoperatively, lumbar drain was placed in 29 (87.9%) patients with an average opening pressure of 27 cmH2O. Encephaloceles were found in 29 patients (87.9%). Average post-operative follow-up duration was 11.6 months, by when 28 patients experienced resolution of CSF leak and most presenting symptoms, although nine patients had residual, decreased hearing in affected ear. Five patients (16%) required eventual VPS for leak recurrence.

Reviewing preoperative and intraoperative factors, higher BMI was associated with need for postoperative shunt (p=0.1).

Conclusion : MCF approach to repair CSF leaks due to lateral skull base defects is a safe and effective procedure. Early results suggests patients with higher BMI are more likely to fail initial MCF repair. Further analysis of obesity-related factors and imaging characteristics are ongoing and will be reported.