Introduction: Small case series have suggested that cerebral amyloid angiopathy (CAA) and reversible cerebral vasoconstriction syndrome (RCVS) are the most common causes of non-traumatic convexal SAH (cSAH). Our objective was to describe the spectrum of clinical and imaging features in a large series of non-traumatic cSAH patients.
Methods: A retrospective observational study of consecutive patients with non-traumatic cSAH was performed. The Mayo Clinic Medical Records Linkage system was used to identify all patients evaluated at Mayo Clinic in Rochester with potential non-traumatic cSAH between January 1, 1996 and October 1, 2014. Clinical and radiologic data were abstracted from the comprehensive medical record.
Results: We identified 88 patients [median age, 64 years (range: 25-85)] with non-traumatic cSAH. The most common causes were reversible cerebral vasoconstriction syndrome (26, 29.5%), cerebral amyloid angiopathy (23, 26.1%), indeterminate (14, 15.9%), and endocarditis (9, 10.2%). Other causes include posterior reversible encephalopathy syndrome, cerebral vein thrombosis, vasculitis, carotid occlusive disease, thrombosed developmental venous anomaly, and hyperperfusion syndrome after carotid revascularization. CAA patients commonly presented at an older age than RCVS patients (75 years vs 51 years, p<0.0001). The most common clinical presentation for CAA was sensorimotor dysfunction while thunderclap headache was the most common presentation of RCVS. Thirteen patients (14.7%) had recurrent cSAH and twelve patients (13.6%) had a subsequent intracerebral hemorrhage over a median follow up of 16 months. The risk was high among CAA patients, with subsequent lobar ICH occurring in 43.5% of cases, superficial siderosis in 95%, and recurrent cSAH in 39.1%, compared to 3.8%, 28.5% and 7.7% respectively in RCVS.
Conclusions: Our study demonstrates the clinical diversity of cSAH. Older age, sensorimotor dysfunctions suggest CAA as the underlying cause. Younger age and thunderclap headache predict RCVS. Various other causes also need to be considered in the differential diagnosis. CAA patients have high rates of subsequent lobar ICH, development of superficial siderosis, and recurrent cSAH.