Prognosis and prognostic factors for unexplained subarachnoid hemorrhage: Review of 84 cases

OBJECTIVE: We conducted a retrospective study to investigate the prognosis, possible prognostic factors, and long-term natural history of subarachnoid hemorrhage of unexplained cause. METHODS: This report contains a retrospective analysis of data for 84 patients with subarachnoid hemorrhage of unknown cause who were monitored for 1 month to 9.5 years, with an average follow-up period of 5.6 years. We evaluated the associations between computed tomographic (CT) scan features, clinical grade, loss of consciousness during hemorrhage, ventricular ratio, angiographic spasm, complications (such as death resulting from ischemia, early rebleeding, late rebleeding, epilepsy, hydrocephalus, and fixed ischemic deficits), and outcomes, using a nonparametric, two-sample, Kolmogorov-Smirnov test. The X² test was used to test the independence of two categorical variables. RESULTS: CT class exhibited a significant association with clinical grade (γ = 0.865, P = 0.006), loss of consciousness during hemorrhage (γ = 0.69, P = 0.001), and ventricular ratio (γ = 0.8175, P = 0.01) but a nonsignificant association with angiographic vasospasm (γ = 0.21, P = 0.2). Death resulting from ischemic complications and fixed ischemic deficits were strongly associated with clinical grade (P = 0.003 and P = 0.008, respectively) but weakly associated with CT class (P = 0.06 and P = 0.084, respectively). Angiographic vasospasm was strongly associated only with fixed ischemic deficits among complications (P = 0.001). Clinical outcome was strongly positively associated with CT class (γ = 0.685, P = 0.001), clinical grade (γ = 0.81, P = 0.001), and ventricular ratio (γ = 0.57, P = 0.002) but weakly positively associated with loss of consciousness during hemorrhage (γ = 0.459, P = 0.0487) and angiographic vasospasm (γ = 0.48, P = 0.04). CONCLUSION: Our study confirms earlier studies reporting a good prognosis for survival, but it does not confirm the earlier statements regarding low morbidity rates. Although clinical grade and the presence and amount of subarachnoid blood on CT scans are the major prognostic factors related to the incidence of ischemic complications, clinical grade and CT class are also the main parameters, with ventricular ratio, indicating clinical outcomes for patients with subarachnoid hemorrhage of unknown cause.