Introduction: Spontaneous, non-traumatic subarachnoid hemorrhage (SAH) along the convexity is rare and poorly understood. We describe the clinical presentation, radiographic findings and outcomes in such patients.

Methods: We retrospectively identified 733 patients admitted to our institution with a diagnosis of spontaneous non-traumatic subarachnoid hemorrhage (SAH) between 2006-2012. Patients with subarachnoid hemorrhage isolated over the cerebral convexities on their initial non-contrast CT were included. The clinical presentation, diagnostic workup and outcomes were analyzed.

Results: Of these 733 patients, 14(1.9%) had a convexity SAH. 11(78.6%) patients were female, and the average age was 55.9 years. Initial GCS on presentation was 15 in all patients and headache was the most common presenting symptom. A past medical history of hypertension was present in 57.1% of patients. Left sided facial numbness was noted in 1 patient. Mean Hunt Hess grade was 1.5. Initial angiographic studies showed vessel irregularities suggestive of vasculitis or reversible cerebral vasoconstriction syndrome (RCVS) in 2/14 (14.3%) patients. Repeat angiography and MRI of the brain were performed in 35.7% and 71.4% of patients, respectively, all of which were negative. A diagnosis was established in 3/14(21.4%) of the patients including 2 patients with RCVS and 1 hemorrhage secondary to anticoagulant use. All patients had a favorable outcome (GOS-5) upon discharge.

Conclusions: The clinical presentation, etiology and outcomes differ in convexity SAH as compared to cases of SAH concentrated in the basal cisterns. These patients present in a benign manner and initial angiography studies are essential to aid in the diagnosis. RCVS and anticoagulation use are potential causes of this rare type of hemorrhage. These patients have a very good prognosis.

Patient Care: Physicians should be able to better identify convexity SAH and do a more efficient workup of their patients. Vasculitis and/or reversible cerebral vasoconstriction syndrome is part of the differential diagnosis of these patients.

Learning Objectives: By the conclusion of this presentation, participants should be able to understand the key differences in presentation, imaging workup, differential diagnosis and outcome between convexity SAH and SAH in the basal cisterns.

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