Cerebral arteriovenous malformations: influence of angioarchitecture on bleeding risk

Background. To evaluate the angioarchitecture of cerebral arteriovenous malformations (cAVMs) with special regard to its influence on the risk of intracranial haemorrhage. Methods. Clinical and neuroradiological data of 171 patients with cAVMs, who were treated at our department, were analysed retrospectively. The angioarchitectonic data were obtained from angiographic series, cranial CT scans and MR images. A chi(2) test was conducted to correlate the parameters and determine the P values. Findings. The following parameters correlate to an increased risk of haemorrhage: diameter of the nidus less than or equal to2 cm (P<0.001), number of arterial feeders less than or equal to2 (P<0.001), diameter of the main feeder less than or equal to1 mm (P<0.0001), number of veins draining the nidus less than or equal to2 (P<0.001), exclusive deep drainage (P<0.05), and low or middle flow-velocity (P<0.01). Specific angioarchitectonic features such as venous stenoses, varicose dilatation of the draining vein, arterial aneurysms of the feeding artery, arteriovenous fistula within the nidus, contralateral drainage and sinushypo/-aplasia did not alter the bleeding rate. Interpretation. Various angiographic features were correlated with the occurrance of intracranial haemorrhage in patients with cerebral AVMs. In addition to the well-known factors influencing the bleeding risk of cAVMs like size, pattern of venous drainage and location within the brain our data demonstrate the importance to look at the diameter of the main feeder and the number of draining veins showing a better correlation.