title: Outcome correlates with blood distribution in subarachnoid hemorrhage of unknown origin.
abstract: OBJECTIVE
  Between 15 and 30 % of patients with subarachnoid hemorrhage (SAH) have no bleeding source and usually have a benign clinical course and outcome. The objectives of this study were to classify the pattern of blood distribution on initial computed tomography (CT) and to correlate it with clinical outcome in aneurysmal (ASAH) and SAH of unknown origin (SAHuO).
  
  
  METHODS
  We reviewed 112 CTs of SAHuO and 104 CTs of ASAH patients. Blood distribution was classified according to a new grading system (type 0-4) and correlated to Hunt and Hess (H&H) grade and modified Rankin scores (MRS) at short- and long-term follow-up.
  
  
  RESULTS
  Fifty percent of 112 SAHuO patients were classified as type 0 (no visible blood on CT) or 1 (blood restricted to prepontine cisterns). Most ASAH patients presented with bleeding into the lateral Sylvian fissure (66%; type 3) or with intracerebral hemorrhage (27%; type 4) whereas types 0 and 1 were not observed. SAHuO patients were in better clinical condition on admission than ASAH patients (p < 0.0001). H&H grades of SAHuO patients correlated with the amount of subarachnoid blood according to the new classification (p = 0.004). Short-term outcome was obtained from 100% and long-term outcome from 95% patients (follow-up 29 +/- 31 months). Short- and long-term MRS correlated with blood distribution in SAHuO patients (p = 0.012) and was significantly better than in ASAH patients (p < 0.0001). No correlation was observed between blood distribution, H&H grade, and short- and long-term outcome in aneurysmal patients.
  
  
  CONCLUSIONS
  In SAH of unknown origin, a new classification allows to predict outcome based on the extent of blood on CT.
authors.affiliation: Department of Neurosurgery, University Medical Center Freiburg, 79106 Freiburg, Germany.
authors.forename: Michal
authors.initials: M
authors.lastname: Woznica
authors.forename: Steffen K
authors.initials: SK
authors.lastname: Rosahl
authors.forename: Ansgar
authors.initials: A
authors.lastname: Berlis
authors.forename: Astrid
authors.initials: A
authors.lastname: Weyerbrock
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001769:Blood; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D002560:Cerebrovascular Circulation / Q000502:physiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000145:classification* / Q000000981:diagnostic imaging* / Q000209:etiology / Q000628:therapy; D013346:Subarachnoid Space / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000473:pathology; D015996:Survival Rate; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult