Risk Factors and Patterns of Spontaneous New Encephaloceles Following Initial Lateral Skull Base Repair

Objective: To identify risk factors and developmental patterns for new spontaneous encephaloceles following an initial repair. Study design: Retrospective. Setting: Tertiary academic medical center. Patients: Consecutive patients with spontaneous encephaloceles treated at the University of Pennsylvania Health System between October 2012 and October 2024. Main outcome measures: Risk factors for, median time to, and location of new, spontaneous CSF leaks following a prior repair. Results: One hundred seventy-six adults met inclusion criteria. Mean age was 56.8 years (SD: 12.4 y), average BMI was 35.2 kg/m 2 (SD: 8.5 kg/m 2 ), and 110 (62.5%) patients were females. Thirty-two (18%) patients developed new encephaloceles after initial repair, with a median time to recurrence of 1.6 years (IQR: 0.3, 2.9). Of these newly developed skull base encephaloceles, 22 (69%) were ipsilateral, 7 (22%) were anterior, and 3 (9%) were contralateral. Conclusions: Wide exposure and repair of the entire skull base is recommended in patients undergoing lateral encephalocele repair. The existence of new, spontaneous encephaloceles at sites distant from the original repair warrants further investigation into additional physiological risk factors.