Cerebral micro arteriovenous malformations (mAVMs). Review of 13 cases.

In a personal series of 152 cerebral vascular malformation, 13 patients had small (less than 1 cm) parenchymal arteriovenous malformations (mAVMs) with small nidus or fistula and a single normal-sized feeding artery and draining vein. All 13 patients presented with intracerebral haematomas (ICHs). The average age in this group was 31 years with no sex dominance; 8 patients had no antecedent symptoms. In 11 patients the small AMV could be demonstrated angiographically, with the remaining 2 malformations evident at surgery. In addition, all these mAVMs, being superficial (95% cortical), were surgically removable with no perioperative morbidity. They were not accessible by endovascular approach. This population group narrows the concept of occult vascular lesions if high quality angiographic studies are performed. mAVMs are by nature CT and MRI occult.