Locating Spinal Leaks in Spontaneous Intracranial Hypotension: How Many Dynamic Myelographies Does It Take?

Background and purpose: Localizing a cerebrospinal fluid (CSF) leak in spontaneous intracranial hypotension (SIH) patients is of utmost importance when pursuing a targeted therapy. The study aimed to evaluate the accuracy of dynamic myelography techniques in localizing spinal CSF leaks and report the number of examinations required, stratified by leak type and spinal level.

Materials and methods: Consecutive SIH patients with a spinal longitudinal extradural CSF collection (SLEC) investigated at our department from January 2013 to February 2025 were screened. All included patients underwent a dynamic myelography work-up to localize the level of spinal CSF leak using conventional dynamic myelography (CDM), and/or dynamic computed tomography myelography (DCTM).

Results: In total, 198 SLEC positive SIH patients (mean age: 50 ± 12 years; 67% female, 133/198) were included. In total, 147 patients had a ventral (74%), 49 patients had lateral (25%), and two patients had a primary dorsal (1%) leak. The spinal CSF leak was localized with the first, second, third or fourth dynamic myelography in 97 (49%), 70 (35%), 16 (8%), 11 patients (6%), respectively. The median number of myelography exams (CDM + DCTM) per patient to localize a CSF leak was 2 (IQR 1-2; range 1-8); 1 (IQR 1-2; range 1-5) for ventral, 2 (IQR 1-2; range 1-6) for lateral and 6 (IQR 5-7; range 4-8) for dorsal leaks. In total, 160 patients (81%) were referred for microsurgical closure. The dural leak was identified intraoperatively on the indicated vertebral level in 153 patients (96%), in 2 patients (1.3%) spontaneous sealing occurred, in 5 patients (3%) wrong-level surgery occurred.

Conclusions: Dynamic myelography exams accurately and reliably localize spinal CSF leaks in SIH patients with SLEC. In about half of the patients, the level of the leak can be localized with the first CDM. In case of a repeat dynamic myelography, the technique and patient positioning can be adopted according to the results of the previous exam. Primary dorsal leaks are rare, but due to the low level of suspicion, pose a diagnostic challenge.

Abbreviations: CSF: Cerebrospinal Fluid; CDM: Conventional Dynamic Myelography; DSM: Digital Subtraction Myelography; DAP: Dose-Area Product; DLP: Dose-Length Product; DCTM: Dynamic Computed Tomography Myelography; EBP: Epidural Blood Patch; ICHD: International Classification Of Headache Disorders; IQR: Interquartile Range; PMCT: Post-Myelo CT; SLEC: Spinal Longitudinal Extradural CSF Collection; SIH: Spontaneous Intracranial Hypotension; SD: Standard Deviation; WLS: wrong-level surgery.