Among 1328 patients of ischemic stroke undergoing cerebral angiography, there were 8 patients (0.6%) in whom the diameter of the extracranial internal carotid artery ipsilateral to the symptomatic hemisphere was less than 1 mm on the angiogram. These patients demonstrated mild to moderate hemiparesis. In 5 of 6 patients with 4-vessel angiographic study, there was entry of blood into the ischemic hemisphere via collateral channels. However, the amount of the collateral flow seemed insufficient, except for one patient. Ulcer formation was noted at the stenotic site in 5 of the 8 patients. Narrowing of the contralateral internal carotid artery was found in 5 of 7 cases in which bilateral carotid angiography was performed.
Five of 8 patients underwent carotid endarterectomy, and the other three were treated conservatively. Among 5 operated cases, three alert patients improved, one alert patient showed neither improvement nor deterioration, and one somnolent patient, in whom the blood supply to the symptomatic hemisphere was only from the extremely narrow internal carotid artery, died after a large postoperative low-density area formed in the symptomatic hemisphere probably due to acute restoration of blood into the ischemic brain tissue.
Among 3 conservative cases, the carotid lesion in one patient immediately changed from stenosis into occlusion and she died of tentorial herniation due to a massive infarction. One patient died of a new infarction 9 months later. In one patient the neurological deficits improved soon and she developed no ischemic symptoms in the follow-up period of 2 years.
Thus, it is apparent that neurological symptoms due to hemodynamic insufficiency resulting from carotid stenosis is of rare occurrence. They seem to develop only when extreme stenosis accompanied by poor collateral circulation. Therefore, carotid endarterectomy, in general, should be aimed at the elimination of the source of embolism rather than at an improvement of cerebral blood flow. Endarterectomy for hemodynamic insufficiency can be safely carried out in patients with mild neurological deficits and is effective in prevention of further reduction of the blood flow. However, it may be followed by development of hemorrhage or swelling in the ischemic lesion if the ischemia is severe.
