Distinguishing clinical and radiological features of non‐traumatic convexal subarachnoid hemorrhage

Background and purpose The full spectrum of causes of convexal subarachnoid hemorrhage ( cSAH ) requires further investigation. Therefore, our objective was to describe the spectrum of clinical and imaging features of patients with non‐traumatic cSAH . Methods A retrospective observational study of consecutive patients with non‐traumatic cSAH was performed at a tertiary referral center. The underlying cause of cSAH was characterized and clinical and imaging features that predict a specific etiology were identified. The frequency of future cSAH or intracerebral hemorrhage ( ICH ) was determined. Results In all, 88 patients [median age 64 years (range 25–85)] with non‐traumatic cSAH were identified. The most common causes were reversible cerebral vasoconstriction syndrome ( RCVS ) (26, 29.5%), cerebral amyloid angiopathy ( CAA ) (23, 26.1%), indeterminate (14, 15.9%) and endocarditis (9, 10.2%). CAA patients commonly presented at an older age than RCVS patients (75 years versus 51 years, P < 0.0001). Thirteen patients (14.7%) had recurrent cSAH , and 12 patients (13.6%) had a subsequent ICH . However, the risk was high amongst those with CAA compared to those caused by RCVS , with recurrent cSAH in 39.1% and subsequent lobar ICH in 43.5% of CAA cases. Conclusions Our study demonstrates the clinical diversity of cSAH . Older age, sensorimotor dysfunction and stereotyped spells suggest CAA as the underlying cause. Younger age and thunderclap headache predict RCVS . Yet, various other causes also need to be considered in the differential diagnosis.