抄録
Two cases of intracranial aneurysms, arising from the origin of anomalous middle cerebral arteries were reported. One case showed a rather classical history of subarachnoid hemorrhage and duplication of the middle cerebral artery beside the ruptured aneurysm. The other case was found incidentally with chronic subdural hematoma while performing carotid angiography, and an accessory middle cerebral artery was seen originating from the A1 portion of the anterior cerebral artery as well as an IC-PC aneurysm.
According to Teal's definition, an anomalous middle cerebral artery arising from the anterior cerebral artery should be termed as the accessory middle cerebral artery, whereas the duplication of the middle cerebral artery should originate from the internal carotid artery proximal to the Al-M1 origin. Twenty-three cases of aneurysms associated with those anomalous middle cerebral arteries have been reported, among which 8 cases were found to have the accessory middle cerebral artery and 15 cases were with duplication of the middle cerebral artery. Location of these aneurysms suggested both congenital and acquired factors as the etiology.
