Clinical study on nonaneurysmal subarachnoid hemorrhage

Objective To investigate the clinical characters of nonaneurysmal subarachnoid hemorrhage and compare perimesencephalic nonaneurysmal subarachnoid hemorrhage(PMN SAH),nonperimesencephalic nonaneurysmal subarachnoid hemorrhage(nPMN SAH).Methods Patients with spontaneous SAH,in whom the initial DSA or CTA result was normal,underwent another investigation(CTA/DSA).If the results of both of these were negative,a second CTA/DSA was done after 3 to 4 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 as PMN SAH and n-PMN SAH.Results There were 51 patients in whom the results of the first DSA and CTA were both negative.Of 51 patients,an aneurysm was demonstrated at a second CTA/DSA in 4 patients and 6 died before a second DSA could be done.After excluding these,there were 29 patients with PMN SAH and 12 with nPMN SAH.There was no mortality in these patients with a mean follow-up of 2.3 years,all patients with PMN SAH and 83.3%of patients with nPMN SAH had a good outcome.Conclusions The nPMN SAH group have a better clinical course and prognosis than those with aneurismal SAH,but not as good as that in the PMN SAH group.A second DSA is mandatory to avoid missing an aneurysm.