Prevalence of Intraoperative Superior Semicircular Canal Dehiscence in Spontaneous Cerebrospinal Fluid Leak Patients.

Abstract

Objective: Determine superior semicircular canal dehiscence (SSCD) prevalence in lateral spontaneous cerebrospinal fluid leak (sCSFL) patients and assess the predictive value of CT in identifying SSCD.

Study design: Retrospective cohort study.

Setting: Tertiary referral center.

Patients: sCSFL patients surgically treated between January 2015 and July 2025.

Interventions: Preoperative high-resolution CT and middle fossa craniotomy (MCF) skull base repair.

Main outcome measures: Preoperative CT prevalence of near-dehiscence or definite SSCD and intraoperative near-dehiscence ("blue-lined") or definitive SSCD.

Results: One hundred eighty-two MCF repairs were performed on 161 patients (66.0% female). Intraoperative SSCD (7.1%) and "blue-lined" near-dehiscence (9.9%) were both present at lower rates than expected based on CT findings (13.1% SSCD, 12.6% near-dehiscence). Compared with patients with a nondehiscent superior canal intraoperatively, those patients with SSCD or near-dehiscence showed no significant differences in mean±standard deviation age (55.0±10.0 vs. 58.2±12.9 y), BMI (38.9±8.6 vs. 39.3±7.5 kg/m 2 ), AHI (28.7±33.7 vs. 32.2±34.6 events/h), or opening pressure (24.0±10.4 vs. 22.6±7.4 cm H 2 O). Patients with intraoperative SSCD or near-dehiscence were more likely to report preoperative dizziness (OR=4.97, 95% CI=1.71-13.05, P =0.001). CT demonstrated 80.6% sensitivity, 85.4% specificity, 53.1% PPV, and 95.6% NPV for detecting SSCD or near-dehiscent findings.

Conclusions: The intraoperative prevalence of SSCD and near-dehiscence (17%) in sCSFL patients was substantially higher than the general population, yet significantly lower than rates predicted by preoperative CT. Obesity, sleep apnea, and intracranial pressure do not predict intraoperative SSCD in this cohort. CT should guide the need for intraoperative confirmation of SSCD in patients with sCSFLs.