Risk factors for subdural hematoma in spontaneous intracranial hypotension are male sex, longer disease duration, and repeated epidural blood patches.

PURPOSE: To investigate the clinical characteristics and risk factors for subdural hematoma (SDH) in patients with spontaneous intracranial hypotension (SIH), with a focus on male sex, disease duration, and repeated epidural blood patch (EBP) procedures. METHODS: This retrospective cohort study included 579 consecutive SIH patients admitted between June 2019 and November 2025. Patients were divided into an SDH group (n = 101) and a non-SDH group (n = 478) based on brain imaging. Demographic data, clinical characteristics, laboratory parameters, brain imaging features, spinal imaging findings, and treatment details were collected. RESULTS: SDH patients were more frequently male (60.4% vs. 32.4%, P < 0.001), older (45.4 ± 12.7 vs. 41.6 ± 9.5 years, P = 0.005), and had longer disease duration (52.3 ± 23.1 vs. 39.2 ± 18.3 days, P < 0.001). They exhibited higher systolic blood pressure (122.7 ± 16.4 vs. 118.8 ± 16.4 mmHg, P = 0.033) and more neurological deficits (30.7% vs. 10.3%, P < 0.001). Brain imaging showed increased frequency of brain sagging (55.5% vs. 40.8%, P = 0.007), dural enhancement (80.2% vs. 64.4%, P = 0.002), venous distension (56.4% vs. 39.1%, P = 0.001), and subdural effusion (36.6% vs. 25.5%, P = 0.023) in the SDH group. Spinal imaging revealed more identifiable leaks (93.1% vs. 77.8%, P < 0.001). The SDH group underwent more EBP procedures (1.43 ± 0.64 vs. 1.23 ± 0.51, P = 0.004). Multivariate analysis identified male sex, age, disease duration, dural enhancement, and number of EBP procedures as independent SDH risk factors (P < 0.05). CONCLUSION: Male sex, longer disease duration, dural enhancement on brain imaging, and repeated EBP procedures were independent risk factors for SDH in patients with SIH, highlighting a need for close monitoring in high-risk individuals.