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 non-aneurysmal 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 5.5years; 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 non-aneurysmal SAH with an aneurysmal pattern of bleeding have more complications, and the initial clinical situation has a significant impact on their prognosis.