title: Subdural effusions in the posterior fossa associated with spontaneous intracranial hypotension.
abstract: BACKGROUND
  Misdiagnosis of spontaneous intracranial hypotension remains a problem, despite increasing recognition.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, University of Yamanashi, Japan.
authors.forename: Arata
authors.initials: A
authors.lastname: Watanabe
authors.forename: Toru
authors.initials: T
authors.lastname: Horikoshi
authors.forename: Mikito
authors.initials: M
authors.lastname: Uchida
authors.forename: Hidehito
authors.initials: H
authors.lastname: Koizumi
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Yamazaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kinouchi
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001932:Brain Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000532:radiotherapy; D003388:Cranial Fossa, Posterior / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D003704:Dementia / Q000150:complications; D003947:Diagnostic Techniques, Radioisotope; D004388:Dura Mater / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006261:Headache / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D019585:Intracranial Hypotension / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D011878:Radiotherapy / Q000009:adverse effects; D013353:Subdural Effusion / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D013355:Subdural Space / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology