Prognosis and prognostic factors in nonaneurysmal perimesencephalic hemorrhage: A follow-up study in 29 patients

BACKGROUND Perimesencephalic nonaneurysmal hemorrhage is a benign form of subarachnoid hemorrhage with a low risk of rebleeding. The authors conducted a retrospective study to investigate the prognosis, possible prognostic factors, and long-term natural history in perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH). METHODS This report contains a retrospective analysis of 29 patients with PNSH who were followed from 1 month to 8 years with an average follow-up period of 5.4 years. We evaluated computed tomography (CT) scan features; clinical grade; loss of consciousness during hemorrhage; ventricular ratio; angiographic spasm; complications such as ischemic complications, early rebleeding, late rebleeding, epilepsy, hydrocephalus, and fixed ischemic deficit; and outcome. RESULTS There were 7 men and 22 women, and the ages ranged from 22 to 69 years (mean 49.5 years). In the group with PNSH 93% of the patients were in grade I–II, as compared to 70.8% of patients with non-PNSH according to the Hunt and Hess system. Loss of consciousness during hemorrhage was detected in 9 patients (31%). We observed acute hydrocephalus in 4 patients (13.7%). The first cerebral four-vessel angiograms disclosed vasospasm in 3 patients (10.3%). Patients with PNSH have the best outcome according to the activities of daily living (ADL) grading system when compared with other groups of patients with negative angiogram (aneurysmal pattern and invisible blood). CONCLUSION This study provides evidence that patients with PNSH have an uncomplicated course and a particularly favorable outcome.