Detection of Cerebrospinal Fluid-venous Fistulas Using Digital Subtraction Myelography in Refractory Spontaneous Intracranial Hypotension: A Single-center Study in an Asian Population

Cerebrospinal fluid-venous fistulas are increasingly recognized as a cause of spontaneous intracranial hypotension, particularly in patients who do not respond to conventional therapies. Although widely reported in Western populations, their prevalence and diagnosis in Asian cohorts remain underexplored. This study aimed to evaluate the utility of digital subtraction myelography in diagnosing cerebrospinal fluid-venous fistulas in Japanese patients with refractory spontaneous intracranial hypotension. We retrospectively analyzed adult patients with spontaneous intracranial hypotension who underwent digital subtraction myelography at our hospital between December 2024 and July 2025. The inclusion criterion was failure of 3 or more epidural blood patches. Digital subtraction myelography was performed using a standardized protocol with tilt-table positioning and contrast-enhanced imaging. The clinical and imaging data were reviewed. Ten patients (15 digital subtraction myelography studies) were included. Cerebrospinal fluid-venous fistulas were detected in 6 of 7 spinal longitudinal epidural collections-negative patients (85.7%). Spinal longitudinal epidural collections-positive patients (3/10) did not have cerebrospinal fluid-venous fistulas. Computed tomography after digital subtraction myelography demonstrated contrast accumulation in the renal pelvis in 88.9% of the cases with positive cerebrospinal fluid-venous fistula or spinal longitudinal epidural collection findings. One illustrative patient underwent Onyx embolization, resulting in marked symptom improvement. In this pilot study, cerebrospinal fluid-venous fistulas were found to be a relevant and treatable cause of refractory spontaneous intracranial hypotension in Asian patients. Digital subtraction myelography proved to be a valuable diagnostic tool, particularly in the absence of spinal longitudinal epidural collections on initial imaging.