Nontraumatic Convexity Subarachnoid Hemorrhage: Different Etiologies and Outcomes

Nontraumatic convexity subarachnoid hemorrhage (cSAH) is a rarely reported condition with multiple etiologies. We report the clinical presentation, imaging findings, etiologies, and long-term outcomes of a case series of cSAH.We retrospectively analyzed consecutive cases of cSAH, admitted at a Stroke Unit of a tertiary hospital (January 2006 to March 2012). Recorded variables were demographics, clinical presentation, complementary investigation, etiology, and outcome.We included 15 patients (9 men, median age of 65 years), 7% of the 210 nontraumatic SAH patients in this period. The most common clinical manifestation was a focal neurologic deficit. Predominant location of the cSAH was frontal. In 5 cases, there was a clinical significant internal carotid artery (ICA) atheromatous stenosis, ipsilateral to cSAH. Two patients had a possible cerebral amyloid angiopathy (CAA) at presentation. There were 2 cases of reversible cerebral vasoconstriction syndrome, 1 cerebral venous thrombosis, 2 dural fistulae, and 3 undetermined. Short-term outcomes were good in most patients. At follow-up (24.3 months), 2 of the patients with undetermined etiology had a lobar hematoma conferring a severe disability, and the diagnosis of CAA was made. There were no other relevant events or added disability in the other patients.Significant ICA atherosclerotic stenosis was the most frequent cause of cSAH in our series, reinforcing that cSAH should prompt vascular imagiological evaluation including cervical vessels. Outcomes in cSAH seem to be related to etiology. Patients with undetermined etiology should be followed up because cSAH may be the first manifestation of CAA.