Clinical Course of Non-Traumatic Non-Aneurysmal Subarachnoid Hemorrhage: A Single Institution Experience over 10 Years and Review of the Contemporary Literature

To report our experience with a relatively large series of patients with non-traumatic non-aneurysmal subarachnoid hemorrhage (NNSAH) to identify the prognosis associated with different bleeding patterns as well as a further diagnostic work-up to determine the underlying cause. 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. 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%). 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.