Short- and long-term outcomes in non-aneurysmal non-perimesencephalic subarachnoid hemorrhage

Objective: Our aim was to assess the short-and long-term prognosis in patients suffering from non-aneurysmal non-perimesencephalic SAH (Na-NPM-SAH). Methods: Based on admission CT-scan, SAH was categorized as perimesencephalic (PM) or non-perimesencephalic (NPM). Based on digital subtraction angiography (DSA) results, patients were classified as normal DSA (Na-SAH) or aneurysmal SAH (aSAH). Between 1997 and 2010, 67 of 571 patients with non-traumatic SAH (11.7%) suffered from non-aneurysmal non-perimesencephalic SAH. Retrospective analyses of the 67 patients were undertaken, and compared with the aneurysmal SAH group. Long-term follow-up was assessed. Results: The cohort consisted of 67 Na-NPM-SAH patients, mean age 54.8 years (range: 21-84), 56.7% male. Acute phase: 10.4% mortality and 3% rebleeding (two patients) during the acute phase. Long-term: extensive follow-up was possible in all except one of the survivors at discharge. Mortality was 6.6% during the 510 patient-years follow-up period (median follow-up time per patient, 8.95 years); rebleeding rate was 0-1.6%. An aneurysmal source was found in 13% of patients who underwent a second angiography. Aneurysmal SAH: 312 patients, with confirmed aneurysm by angiography. The mortality rate for Na-NPM-SAH during the acute phase was 10.4%, vs. 20% for aneurysmal SAH in the general database, p = 0.049. Discussion: Na-NPM-SAH patients without an identifiable bleeding source on initial angiography might have a more benign short-and long-term prognosis than aneurysmal SAH patients. Our study confirms an important diagnostic advantage of a second arteriography. Still, despite the major concern of an undetected aneurysm, the long-term rebleeding rate was low in this subgroup of patients.