Differences between intracranial vascular malformation types in the characteristics of their presenting haemorrhages: prospective, population-based study.

OBJECTIVE: To determine the imaging and demographic characteristics of intracranial haemorrhages, which are subsequently found to be due to an underlying intracranial vascular malformation (IVM). METHODS: We compared the demographic and brain imaging characteristics of adults presenting with intracranial haemorrhage, subsequently found to be due to a brain arteriovenous malformation (BAVM), dural arteriovenous fistula (DAVF) or cavernous malformation (CM) in a prospective, population-based cohort of adults diagnosed for the first time with an IVM (The Scottish IVM Study (SIVMS)). RESULTS: Of the 141 adults in SIVMS who presented with intracranial haemorrhage, those with CMs presented at a younger age and were less handicapped. A total of 115 (82%) had intracerebral haemorrhage (ICH) with or without subarachnoid, intraventricular or subdural extension. ICH without extension into other compartments accounted for all CM bleeds, but only 50% of BAVM and DAVF bleeds. Median haematoma volumes differed (Kruskal-Wallis, p<0.0001): ICH due to BAVM (16.0 cm3, inter-quartile range (IQR) 4.7 to 42.0) and DAVF (14.1 cm3, IQR 4.9 to 21.5) were similar, but CM haematoma volumes were smaller (median 1.8 cm3, IQR 1.3 to 4.3). These findings were robust in sensitivity analyses. Small haematoma volumes occurred among all IVM types; the largest haematoma volume due to CM was 12 cm3, and volumes of >34 cm3 were only due to BAVM. CONCLUSIONS: Intracranial haemorrhages found to be due to IVMs differ in adults' age of presentation and clinical severity, as well as the volume and distribution of the haematoma within the brain compartments.