Postoperative Opening Pressure Rebound After Spontaneous Cerebrospinal Fluid Leak Repair

BACKGROUND AND OBJECTIVES: Spontaneous cerebrospinal fluid (sCSF) leaks are frequently linked to underlying intracranial hypertension. Intraoperative opening pressure (OP) is used to assess intracranial pressure during repair. However, active leakage can act as a physiological release valve, underestimating true pressure. This study evaluates postoperative OP changes after surgical closure of spontaneous skull base leaks and identifies predictors of substantial pressure increase. METHODS: A retrospective review analyzed patients undergoing surgical repair for anterior or lateral sCSF leaks at our institution between 2009 and 2025. Included patients had prerepair and postoperative OP measurements within 6 weeks of surgery. Patients were stratified by a ≥25% OP increase after repair. RESULTS: A total of 46 patients met inclusion criteria. The mean prerepair OP was 18.92 ± 5.20 cm H 2 O, significantly increasing to 23.57 ± 9.04 cm H 2 O postoperatively (mean increase +4.64 cm H 2 O; 95% CI, 1.58-7.70; P = .004). Eighteen patients (39.1%) demonstrated a ≥25% OP increase, with the mean OP rising 89.6% from 16.75 to 31.75 cm H 2 O. Active leak at surgery was strongly associated with postoperative pressure rise (100% vs 28.6%, P < .001). Prerepair OP was significantly lower in the ≥25% increase subgroup ( P = .021). No recurrences occurred during a mean follow-up of 24.9 months. CONCLUSION: OPs may significantly increase after closure of sCSF leaks, especially in patients with active leakage. Normal intraoperative OP does not rule out underlying intracranial hypertension. These findings support the concept of masked intracranial hypertension, emphasizing the need for careful postoperative pressure reassessment.