Nonaneurysmal nonperimesencephalic subarachnoid hemorrhage: is it a benign entity?

BackgroundAlthough the clinical profile of patients with PMN SAH is well documented, there are scarce data available for patients with nonaneurysmal n-PMN SAH. In the present study, the clinical characteristics of patients with n-PMN SAH were analyzed and compared with those of PMN SAH and aneurysmal SAH.MethodsPatients with spontaneous SAH, in whom the initial DSA or 3-dimensional CTA result was normal, underwent another investigation (CTA/DSA). If the results of both of these were negative, a second DSA was done after 4 to 6 weeks. Patients in whom even the second DSA failed to reveal an aneurysm or any other vascular abnormality were labeled as nonaneurysmal SAH. Within this group, 2 different types were identified: PMN SAH and n-PMN SAH.ResultsThere were 61 patients in whom the results of the first DSA and CTA were both negative. In 2 of these patients, an aneurysm was demonstrated at a second DSA. Seven patients died before a second DSA could be done. After excluding these, there were 18 patients with PMN SAH and 34 with n-PMN SAH. There was no mortality in these patients; and at a mean follow-up of 1.8 years, all patients with PMN SAH and 94.1% of patients with n-PMN SAH had a good outcome. Associated comorbid illnesses were more frequent in patients with PMN SAH and n-PMN SAH as compared with the aneurysmal SAH patients.ConclusionsOnce an aneurysm is definitely excluded, patients with n-PMN SAH have a good outcome, and like PMN SAH, have a benign clinical course. However, a second DSA is mandatory to avoid missing an aneurysm or any other vascular lesion.