Lumbar Drain Removal Timing After Open Skull Base Surgery for Malignant Tumors: A Single-Institution Observational Study

Objectives: The optimal timing of lumbar drain (LD) removal following open skull base surgery for malignant tumors remains poorly defined. This study describes practice variation in LD removal timing and examines its association with postoperative complications. Design: Single-institution retrospective cohort study. Setting: Tertiary cancer center (National Cancer Center Hospital, Tokyo, Japan). Participants: Consecutive patients who underwent open skull base surgery for malignant tumors with intraoperative LD placement between January 2010 and July 2025 (n = 104). Main Outcome Measures: Composite of postoperative non-contusion complications (CSF leakage, meningitis, tension pneumocephalus, cerebral infarction, intracranial hematoma, epilepsy). Propensity score–based overlap weighting (OW) and Firth’s penalized logistic regression were used for adjusted analyses. Results: Among 104 patients, 88 (84.6%) underwent immediate LD removal and 16 (15.4%) underwent late removal (median 3 days). Non-contusion complications occurred in 6 patients (6.8%) in the immediate group and 3 patients (18.8%) in the late group. Overlap-weighted analysis showed a numerically lower estimated risk with immediate removal (OR 0.23; 95% CI 0.01–4.02; weighted risks 4.5% vs. 16.7%; absolute difference −12.3%). A consistent directional trend was observed in the dural resection subgroup (n = 75; OR 0.16; 95% CI 0.01–3.79; difference −17.9%). Confidence intervals were wide and statistical significance was not reached in any analysis. Conclusions: The immediate removal group showed a numerically lower estimated complication rate, though results were not statistically significant and should be interpreted with caution given the small sample size and potential era confounding. These hypothesis-generating findings warrant prospective multicenter validation.