Abstract Background and aims Chronic subdural hematoma (cSDH) is the most common intracranial hemorrhage, characterized by slowly expanding subdural fluid collections that ultimately cause brain compression and neurological impairment. The underlying pathophysiology remains incompletely understood. An increasingly recognized and directly treatable cause are spontaneous spinal cerebrospinal fluid (CSF) leaks. This study aimed to estimate the prevalence of spinal CSF leaks in patients presenting with cSDH. Methods This interim analysis derives from a prospective, monocentric observational study of patients admitted with cSDH to the Department of Neurosurgery, University Medical Center Freiburg (07/2024–01/2026; NCT06323434). Standard cSDH treatment was followed by MRI of the brain and spine according to standard-workup in spontaneous intracranial hypotension. Patients with intermediate leak risk (Bern Score ≥3) or orthostatic headache underwent dynamic myelography. The primary outcome was the proportion of confirmed CSF leaks. Results Of 166 eligible patients, 139 consented; 22 withdrew (total n=117). Seven patients are awaiting myelography, and 21 were lost to follow-up before myelography. Among the 89 patients who underwent myelography, a spinal CSF leak was identified in 15.7% (n=14, 95% CI 9.6–24.7%), with a majority of CSF–venous fistulas (n=12, 13.5%, 95% CI 7.9–22.1%). A more restrictive analysis yields a CSF leak prevalence of 12% (95% CI 7.3–19.1%) among the 117 included patients. Conclusions Spinal CSF leaks represent a relevant and directly curable cause in a substantial proportion of patients with cSDH. These findings challenge prevailing assumptions regarding the relationship between spinal CSF leaks and cSDH and have important implications for future diagnostic pathways. Conflict of interest
Lützen et al. (Fri,) studied this question.