Clinical outcome of spontaneous non-aneurysmal subarachnoid hemorrhage in 108 patients

Background: The cause of spontaneous subarachnoid hemorrhage (SAH) is unknown in 15% of cases; idiopathic SAH has a better prognosis than aneurysmal SAH. When bleeding is confined to the perimesencephalic cisterns, SAH has an especially benign course. Methods: We retrospectively studied 108 patients admitted for spontaneous nonaneurysmal SAH between 1991 and 2004. We divided patients into two groups according to the bleeding pattern at cranial CT: perimesencephalic pattern (n = 60) and aneurysmal pattern (n = 48). We included only patients in whom no source of bleeding was detected at angiography; patients with aneurysmal pattern underwent at least two angiographic examinations. Mean follow-up was 5.5 years; follow-up consisted of telephone interview in 84.7% of patients. Results: All but one patient with perimesencephalic pattern were classified as grade I or II on the Hunt and Hess scale; the exception was the only patient in this group with a complication (hydrocephalus), who was classified as grade IV. Three-quarters of the patients with aneurysmal pattern were classified as grade I or II on the Hunt and Hess scale; 5 patients presented with hydrocephalus that required drainage and 2 with vasospasms without repercussions. No rebleeding or long-term complications were observed in either group. Conclusions: Non-aneurysmal SAH with a perimesencephalic pattern of bleeding has a benign course and excellent short-term and long-term prognosis. Patients with nonaneurysmal SAH with an aneurysmal pattern of bleeding have more complications, and the initial clinical situation has a significant impact on their prognosis.