Acute convexity subarachnoid haemorrhage and cortical superficial siderosis in probable cerebral amyloid angiopathy without lobar haemorrhage

Introduction A cute non-traumatic convexity subarachnoid haemorrhage (cSAH) is increasingly recognised in cerebral amyloid angiopathy (CA). We investigated: (a) the overlap between acute cSAH and cortical superficial siderosis-a new CA haemorrhagic imaging signature and (b) whether acute cSAH presents with particular clinical symptoms in patients with probable CA without lobar intracerebral haemorrhage. Methods MRI scans of 130 consecutive patients meeting modified Boston criteria for probable CA were analysed for cortical superficial siderosis (focal, <= 3 sulci; disseminated, >= 4 sulci), and key small vessel disease markers. We compared clinical, imaging and cortical superficial siderosis topographical mapping data between subjects with versus without acute cSAH, using multivariable logistic regression. Results We included 33 patients with probable CA presenting with acute cSAH and 97 without cSAH at presentation. Patients with acute cSAH were more commonly presenting with transient focal neurological episodes (76% vs 34%; p<0.0001) compared with patients with CA without cSAH. Patients with acute cSAH were also more often clinically presenting with transient focal neurological episodes compared with cortical superficial siderosis-positive, but cSAH-negative subjects with CA (76% vs 30%; p<0.0001). Cortical superficial siderosis prevalence (but no other CA severity markers) was higher among patients with cSAH versus those without, especially disseminated cortical superficial siderosis (49% vs 19%; p<0.0001). In multivariable logistic regression, cortical superficial siderosis burden (OR 5.53; 95% C I 2.82 to 10.8, p<0.0001) and transient focal neurological episodes (OR 11.7; 95% C I 2.70 to 50.6, p=0.001) were independently associated with acute cSAH. Conclusions This probable CA cohort provides additional evidence for distinct disease phenotypes, determined by the presence of cSAH and cortical superficial siderosis.