title: Characterization of risk factor differences in perimesencephalic subarachnoid hemorrhage.
abstract: OBJECTIVE
  The non-aneurysmal perimesencephalic subarachnoid hemorrhage (p-SAH) has a favorable outcome. Our objective was to provide a reason for that assessing the association of putative risk factors with this different type of hemorrhage in comparison to the aneurysmal subarachnoid hemorrhage (a-SAH).
  
  
  METHODS
  We selected 185 consecutive cases of subarachnoid hemorrhage between September 1994 and August 1998 in a hospital-based case-control study and investigated the influence of hypertension, body weight, smoking and the three interacting blood factors hematocrit, fibrinogen and leukocrit.
  
  
  RESULTS
  1) Risk factors for SAH: For the entire study group an association of hypertension with the incidence of SAH was found both in the univariate analysis of this variable alone (P=0.001) and in the multivariate logistic regression (P=0.0001), aside from the risk factors smoking (P=0.0047) and hematocrit (P=0.0001). As to the risk of hypertensive subjects to experience SAH for different reasons, the logistic regression yielded an odds ratio (OR) of 3.54 [CI (95 %): 2.21-5.56]. 2) Risk factors for p-SAH: Patients with p-SAH differ in their risk profile from typical aneurysmal SAH cases with respect to their blood pressure status (P=0.019) and the investigated hemorheological parameters.
  
  
  CONCLUSIONS
  A different association between possible risk factors and the two types of subarachnoid hemorrhages was ascertained. In general there seem to be fewer putative risk factors in the perimesencephalic SAH cases compared to the typical aneurysmal hemorrhages.
authors.affiliation: Neurochirurgische Abteilung, Donauspital, Vienna, Austria. g.kleinpeter@billrothhaus.at
authors.forename: G
authors.initials: G
authors.lastname: Kleinpeter
authors.forename: S
authors.initials: S
authors.lastname: Lehr
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008636:Mesencephalon / Q000098:blood supply* / Q000473:pathology; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013345:Subarachnoid Hemorrhage / Q000209:etiology* / Q000473:pathology*