MATERIAL and METHODS: Between January 2004 and December 2014, 81 patients with angiography-negative non-traumatic subarachnoid hemorrhage (SAH) were treated at our institution. Diagnosis was confirmed with a typical history of spontaneous SAH and cranial computed tomography (CT) scan or lumbar puncture (LP). The patients were grouped according to the bleeding pattern on the CT scan: Group 1: Perimesencephalic (PM) SAH (n=33, 40.7%); Group 2: Non-perimesencephalic (nPM) SAH (n=41, 50.6%); and Group 3: CT-negative NNSAH (n=7, 8.6%). The clinical course, hospitalization period, and complications were noted. All patients underwent an initial four-vessel digital subtraction angiography (DSA). Cranial magnetic resonance imaging (MRI), repeat DSA investigations and spinal MRI were performed in all patients.

RESULTS: The mean hospital stays were 6.3, 14.7 and 10.1 days for patient groups 1, 2, and 3, respectively. The mortality rate was 1.2% (1 patient) in our series. Repeat DSA investigations were positive in two patients (2.5%), both from Group 2 (4.9%). Cranial MRI revealed 100% negative results. Spinal MRI revealed positive results in three patients from Group 2 (7.3%).

CONCLUSION: We suggest our diagnostic work-up for patients with nPM-SAH, namely repeat DSA and spinal MRI, until an evidence-based guideline is established for the patient management. Keywords : Non-aneurysmal subarachnoid hemorrhage, Negative angiography, Perimesencephalic, Non-perimesencephalic, Spinal magnetic resonance imaging, Digital subtraction angiography