[A case report of hypoplasia of the left internal carotid artery manifested as convulsion attack].

A case of hypoplasia of the left internal carotid artery manifested as convulsion was reported. The features and embryological process were reviewed. The case was that of a 25-year-old female who had been afflicted with repeated convulsion for 16 years. CT scan showed a dilated left posterior communicating artery. Cerebral angiography revealed abrupt narrowing of the left internal carotid artery from a few centimeters distal to the bifurcation of the common carotid artery and terminating at the C4 portion. The left cerebral hemisphere was supplied, through well-developed anterior and posterior communicating arteries. On the CT scan with the skull base bone as target, the left carotid canal was smaller than the right one. Single photon emission computed tomogram using Xe showed a slightly low perfusion area in the left cerebral hemisphere. Frequent spike waves were seen on the electroencephalogram. After the left STA-MCA anastomosis, spike waves disappeared and the patient has been free from convulsion for 3 years.