Treatment Outcomes of Epidural Blood Patch Guided by a Novel Overflow Leak Test with Computed Tomography Myelography in Patients with Intracranial Hypotension: A Case Series.

Abstract

To describe the treatment outcomes of epidural blood patch (EBP) guided by a novel overflow leak test (OLT) combined with computed tomography myelography (CTM) in patients with intracranial hypotension, with focus on consistency and discrepancy between CTM and OLT findings. CTM followed by OLT was performed in 18 adults with a cerebrospinal fluid pressure of ≤60 mmH₂O. Patients were categorized according to consistency or discrepancy between CTM and OLT findings: Group A, matching leak signals in CTM and OLT; Group B, leak signals detected by OLT only; Group C, discrepancy in leak signal sites between CTM and OLT; Group D, no leak signal detected by both CTM and OLT. EBPs were applied according to the treatment policy, and associations between the radiological categorization and treatment outcomes were determined. Thereafter, using CT and magnetic resonance imaging phantoms, we investigated the minimal amount of injected agent leaking from the lumbar puncture site visible, which could result in a false-positive signal in CTM and OLT. Complete recovery following EBP was achieved for 13 (72%) patients; these included 50%, 82%, 100%, and 0% patients in Groups A, B, C, and D, respectively. In CT myelography phantoms, even 1 μL of contrast agent produced positive findings, whereas OLT phantoms required a minimum of 1000 μL. These results suggest the potential additive diagnostic value of OLT when performed with CTM. The discrepancy in radiological findings could be partly explained by susceptibility to the contrast agent leaking from the lumbar puncture site.