title: Pathophysiology and diagnosis of spontaneous intracranial hypotension.
abstract: BACKGROUND
  Spontaneous intracranial hypotension (SIH) has become a well-recognized syndrome. However, diagnosis of SIH is still challenging. The problem with SIH is that the precise mechanism of cerebrospinal fluid (CSF) leakage remains largely unknown and there is no definite diagnostic criterion in the imaging.
  
  
  METHODS
  The clinical findings of our ten cases and 301 literature reports on SIH were investigated in a retrospective analysis to clarify the pathophysiology of CSF leakage, correlate the findings of imaging studies and determine the most adequate diagnostic criteria.
  
  
  RESULTS
  The events precede symptoms of SIH were categorized as traumatic, secondary and strictly spontaneous (62%). The location of the spinal CSF leak remains undetectable in approximately 50% of cases reported. In 93% of patients, the CSF leakage sites were detected at the cervical or thoracic level of the spine. On recent MRI studies, 88% of patients showed spinal epidural fluid collections that most likely represent CSF leakage. MR myelography using heavily T2-weighted fast-spin-echo sequence can clearly demonstrate the site of CSF leakage. Although numerous treatment options are available, none of the treatments have been evaluated by randomized clinical trials. In 48% of papers, autologous epidural blood patch (EBP) was the treatment of choice in patients who have failed initial conservative management. Forty-nine percent of patients showed relief of symptoms after up to three repeated EBPs.
  
  
  CONCLUSIONS
  We propose new diagnostic criteria of SIH to avoid misdiagnosis.
authors.affiliation: Department of Neurosurgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. shima@ndmc.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Shima
authors.forename: S
authors.initials: S
authors.lastname: Ishihara
authors.forename: S
authors.initials: S
authors.lastname: Tomura
mesh_terms: D002555:Cerebrospinal Fluid / Q000502:physiology*; D004824:Epidural Space / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D019585:Intracranial Hypotension / Q000175:diagnosis* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011643:Publishing / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013353:Subdural Effusion