title: MR imaging in pretruncal nonaneurysmal subarachnoid hemorrhage: is it worthwhile?
abstract: OBJECTIVE
  The cause of pretruncal (perimesencephalic) nonaneurysmal subarachnoid hemorrhage is not known. MRI of the brain or spine is often performed to exclude any other vascular abnormalities. Its diagnostic value is not known.
  
  
  METHODS
  We used MR imaging of the brain with routine sequences, gadolinium enhancement, and additional thin T1-weighted axial sections following a triple dose of contrast.
  
  
  RESULTS
  We performed MR imaging of the brain in 18 patients with a pretruncal nonaneurysmal subarachnoid hemorrhage. The focal nature of the subarachnoid hemorrhage exclusively in front of the brain stem was confirmed in 14 patients studied within 7 days of the ictus. No vascular abnormalities were found in 17 cases, including 14 patients with gadolinium enhancement. An incidental capillary telangiectasia was found in 1 patient. Fluid-attenuated inverse recovery MR additionally documented blood in the sulci due to cerebrospinal fluid recirculation of blood. Five patients underwent MR imaging of the spine, and no arteriovenous malformations were found.
  
  
  CONCLUSIONS
  MR imaging did not reveal a source of pretruncal subarachnoid hemorrhage. The cost of MR imaging probably outweighs the benefit in the evaluation of this variant of subarachnoid hemorrhage.
authors.affiliation: Departments of Neurology, Mayo Clinic, Rochester, Minnesota, USA. wijde@mayo.edu
authors.forename: E F
authors.initials: EF
authors.lastname: Wijdicks
authors.forename: W I
authors.initials: WI
authors.lastname: Schievink
authors.forename: G M
authors.initials: GM
authors.lastname: Miller
mesh_terms: D001921:Brain / Q000473:pathology; D003362:Cost-Benefit Analysis; D005069:Evaluation Studies as Topic; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000191:economics*; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis*