Underwent Extracranial-intracranial Bypass Research Articles

Evaluation of EC–IC bypass for patients with atherosclerotic occlusive cerebrovascular disease: Clinical and positron emission tomographic studies

The authors report clinical evaluations of extracranial-intracranial (EC-IC) bypass surgery for patients presenting with misery perfusion on positron emission tomography (PET) due to atherosclerotic occlusive cerebrovascular disease. Seven patients underwent PET both before and after undergoing EC-IC bypass surgery. Three of the 7 patients had transient ischaemic attacks (TIAs) and 4 had minor strokes. Five of the 7 had unilateral superficial temporal-middle cerebral artery (STA-MCA) anastomosis, one had bilateral STA-MCA anastomoses and one had STA-MCA anastomosis on one side and carotid endarterectomy on the other side. PET showed postoperative improvement in regional cerebral blood flow and metabolism in 5 of the 7 patients. In the remaining 2 patients, one showed no remarkable changes on PET and the other showed exacerbation on PET due to postoperative cerebral infarction. All three patients who had TIAs had no further TIAs after surgery. Two of the 3 patients postoperatively showed improvement in misery perfusion on PET. In the 4 patients who had minor strokes, 2 showed clinical improvements. One of the 2 showed improvement not only in motor function but also in the higher cortical functions such as verbal and performance intelligence quotients. Changes on PET correlated to the clinical improvement in 4 of 7 patients. The EC-IC bypass is therefore effective in patients with haemodynamic hypoperfusion syndromes by improving the state of low perfusion.

Clinical results of extracranial-intracranial bypass surgery in patients with hemodynamic cerebrovascular disease.

The importance of hemodynamic factors in the pathogenesis and treatment of cerebrovascular disease remains uncertain. The extracranial-intracranial (EC-IC) bypass trial has been criticized for failing to identify and separately analyze those patients with chronic reduction in regional cerebral perfusion pressure (rCPP) who might be most likely to benefit from surgery. Positron emission tomography (PET) measurements of regional cerebral blood flow (rCBF) and blood volume (rCBV) were performed on 29 patients with symptomatic occlusion or intracranial stenosis of the carotid arterial system prior to undergoing EC-IC bypass surgery. Twenty-four patients had evidence of reduced rCPP (increased rCBV/rCBF ratio) distal to the arterial lesion. Of 21 patients who survived surgery without stroke, three suffered ipsilateral ischemic strokes during the 1st postoperative year. A nonrandomized control group of 23 nonsurgical patients' with similar clinical, arteriographic, and PET characteristics experienced no ipsilateral ischemic strokes during the 1st year following PET. Based on these results in 44 patients, the probability that successful surgery reduces the occurrence of ipsilateral ischemic stroke 1 year later was calculated. This probability ranged from 0.045 for a 50% reduction to 0.168 for a 10% reduction. Thus, there was little evidence to suggest that measurements of cerebral hemodynamics can identify a group of patients who would benefit from EC-IC bypass surgery.

Changes in intracranial stenotic lesions after extracranial-intracranial bypass surgery.

The natural history of intracranial arterial stenosis is not well understood. The lesions are pathologically quite diverse, and are subject to resolution, progression, or occlusion. The authors undertook an investigation to examine what effects, if any, extracranial-intracranial (EC-IC) bypass surgery had on the evolution of intracranial arterial stenosis in 18 patients undergoing EC-IC bypass procedures for ipsilateral hemispheric ischemia. There was inaccessible internal carotid artery stenosis in 14 patients, and middle cerebral artery stenosis in four patients. Early (within 2 weeks) and late (at 6 months) postoperative angiography was performed in all patients. During the period of the study, there was a significant change in the arterial stenosis in 50% of the patients (nine of 18). The stenotic artery became occluded in four patients while the grafts were widely patent. The occlusion occurred within a few days after the operation in three of the four cases, and was accompanied by an ischemic stroke in these patients. There was improvement or resolution of the stenotic lesion in five patients; the graft became occluded in two of these cases and was patent but showed poor cortical artery filling in the other three. All these patients remained asymptomatic and the change was detected on routine late postoperative angiograms. It is concluded that arterial stenoses should not be viewed as static or inflexible lesions, and that EC-IC bypass procedures can modify the hemodynamic parameters across stenotic lesions, predisposing them to improvement or worsening. This, in turn, may affect bypass patency. Such hemodynamic interactions are accompanied by ischemic symptoms in some patients, and contribute to the relatively higher morbidity associated with EC-IC bypass surgery in the setting of arterial stenosis.

Extracranial carotid artery injuries.

From December, 1975, to December, 1979, 54 carotid artery injuries have been treated by the Southwestern Medical School Department of Surgery. Seventy-eight percent were due to gunshot wounds, 20% were due to stab wounds, and 2% were secondary to blunt trauma. Thirty-three percent involved the internal carotid artery, and the external carotid artery was involved in 20%. Eighteen percent of the patients presented with a major associated venous injury and 8% with an arteriovenous fistula. Partial or complete disruption accounted for the majority of injuries. There was a 10% mortality rate. Four percent of the deaths were due directly to carotid vascular trauma. Because of our experience we believe, whenever possible, all patients should have the benefit of preoperative arteriography. This allows for a well planned operation and avoids major unnecessary neck dissection. High lesions involving the internal carotid artery may be exposed easily by anterior dislocation of the jaw, thus allowing ready access to the base of the skull. Injuries involving extensive areas of the internal carotid artery (lesions extending intracranially) are best managed by extracranial-intracranial (EC-IC) bypass with internal carotid artery ligation. Severe neurologic deficit is best treated by ligation of the carotid artery. Seven patients have undergone EC-IC bypass and 86% of these returned to or maintained normal neurologic status, while the other 14% remained neurologically stable. It is our impression that the risk of neurologic deficit is lessened by this maneuver without added mortality or morbidity.