Diagnosis and Therapeutic Outcomes of Spontaneous Cerebrospinal Fluid Leak Diagnosed Based on Floating Dural Sac Sign on Thoracic Spine MRI

We retrospectively investigated 30 patients diagnosed with spontaneous cerebrospinal fluid leakage (SCFL), identified by the presence of the floating dural sac sign (FDSS) on thoracic spine magnetic resonance imaging (MRI). FDSS was considered positive when a uniformly wide, circular, low-signal area―representing the dura mater―was observed around the spinal cord on T2-weighted image (T2WI), along with a high-signal intensity gap between the dura mater and the spinal canal on fat-suppressed T2WI. Head MRI findings revealed subdural hematoma in 6 patients, cerebellar ptosis in 5 patients, and dural thickening in 8 patients. An epidural blood patch was administered to 24 patients, resulting in complete symptom resolution in all patients. FDSS findings resolved in 19 patients, while residual fluid collections were noted in 11 patients on follow-up MRI. MRI-based diagnosis and treatment of SCFL are highly effective and clinically useful.