title: Special features of subarachnoid hemorrhage of unknown origin: a review of a series of 179 cases.
abstract: OBJECTIVE
  The aim of this study was to work out the special features of subarachnoid hemorrhage (SAH) of unknown origin in respect of diagnostic evaluation, clinical course, and outcome in a large cohort of patients.
  
  
  METHODS
  We reviewed the data of 179 patients with SAH of unknown origin during 1991 and 2008. The differentiation between perimesencephalic (PM-SAH) and non-perimesencephalic SAH (NON-PM-SAH) was done under consideration of the bleeding pattern on CT scanning.
  
  
  RESULTS
  Among 1226 treated patients with spontaneous SAH over a time period of 17 years, a bleeding source remained undetected on first digital subtraction angiogram (DSA) in 179 patients (16.7%)--47 PM-SAH (26.3%) and 132 NON-PM-SAH (73.7%). The clinical signs of patients with PM-SAH were less marked compared to those with NON-PM-SAH, equally to the Hunt and Hess grade. magnetic resonance imaging (MRI) and MR angiography had 100% negative findings for non-aneurismal bleeding sources in all patients. Second DSA revealed a bleeding source in the NON-PM group in 10.8%. The clinical course of the patients with NON-PM-SAH showed a significantly higher rate of complications and a mortality of about 10%. The outcome was excellent in the PM group, in contrast to a fatal course in 13 cases in the NON-PM group.
  
  
  CONCLUSIONS
  PM-SAH imposed with a mild clinical course and an excellent outcome, without severe complications. In contrast to this, NON-PM-SAH has a significant higher rate of dreaded complications and mortality. It is crucial to make an exact diagnosis of PM-SAH, considering CT scanning during the first 24 hours after occurrence of symptoms and the radiological features.
authors.affiliation: Department of Neurosurgery, University Hospitals Schleswig-Holstein, Campus Kiel, Germany. h.maslehaty@gmx.de
authors.forename: Homajoun
authors.initials: H
authors.lastname: Maslehaty
authors.forename: Harald
authors.initials: H
authors.lastname: Barth
authors.forename: Athanassios K
authors.initials: AK
authors.lastname: Petridis
authors.forename: Alexandros
authors.initials: A
authors.lastname: Doukas
authors.forename: Hubertus
authors.initials: H
authors.lastname: Maximilian Mehdorn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000175:diagnosis* / Q000209:etiology; D013997:Time Factors; D055815:Young Adult