Subdural Effusions in the Posterior Fossa Associated with Spontaneous Intracranial Hypotension

Abstract

Misdiagnosis of spontaneous intracranial hypotension remains a problem, despite increasing recognition. Three patients with spontaneous intracranial hypotension presented with typical findings on lumbar puncture, magnetic resonance (MR) imaging, and radioisotope cisternography. All patients showed subdural effusions in the posterior fossa on axial T2-weighted MR imaging. Axial MR images of 112 patients with other conditions were also screened for this finding. One of three patients had typical orthostatic headache, and the other two had continuous headache. The finding of subdural effusions in the posterior fossa on axial T2-weighted MR imaging disappeared after treatment. Similar findings were found in 14 of 112 patients with other conditions. Most of the patients were over 60 years old or had dementia or previous radiation therapy. Subdural effusions in the posterior fossa can be identified by T2-weighted axial MR imaging, and are useful for the diagnosis of spontaneous intracranial hypotension and for verifying the effectiveness of treatment.