MR findings of spontaneous intracranial hypotension

Purpose: To present the MR features of spontaneous intracranial hypotension (SIH) and to discuss the correlation of MR features with clinical manifestations. Material and Methods: Between 1997 and 2000, 15 patients with SIH underwent brain MR investigation. Lumbar puncture for the measurement of cerebrospinal fluid (CSF) pressure was performed in 6 patients. Follow-up MR was obtained in 8 patients after the clinical symptoms had improved. We analyzed the MR findings of SIH, and discuss them in relation to CSF pressure and clinical manifestations. Results: Fourteen of the 15 patients with SIH had abnormal MR findings. The imaging findings included: diffuse pachymeningeal enhancement in 13 patients; descent of the brain in 6 patients; and subdural effusion/hematoma in 2 patients. Low CSF pressure was shown at lumbar puncture in 5 out of 6 patients. Follow-up MR examination in the symptoms-relieved status demonstrated a recovery of the abnormal MR findings in 6 of 8 patients. Conclusion: Our data revealed that MR is sensitive in diagnosing SIH. The presence of characteristic clinical manifestations and MR features are virtually diagnostic for SIH syndrome. Invasive lumbar puncture is thus reserved for the equivocal cases.