Intracranial atherosclerotic disease is a major contributor to stroke burden.
Individuals with intracranial, symptomatic occlusion of the internal carotid artery or middle cerebral artery are subject to high annual recurrent stroke risks, exceeding 10% per year.
Cerebral hemodynamic insufficiency identifies a sub group of patients with an even higher two year risk of ischemic stroke despite medical therapy.
Extracranial-intracranial (EC-IC) bypass surgery is a surgical procedure performed to prevent strokes by rerouting blood flow around blockages or narrowing in the blood vessels of the brain.
The primary goal of EC-IC bypass surgery is to improve blood flow to areas of the brain that are at risk of stroke due to reduced blood supply.
It is usually considered when there is a large artery blockage, such as the internal carotid artery or middle cerebral artery, that cannot be treated with other methods.
The surgery: blood vessel graft is taken from another part of the body, typically the scalp or the forearm, and is used to create a bypass around the blocked or narrowed vessel in the brain.
Anastomosis of the superficial temporal artery to the middle cerebral artery, is designed to augment brain perfusion.
Vascular sites outside the brain treated with augmented arterial flow typically improves outcomes, however, the brain appears to respond differently to bypass surgery.
Candidates for EC-IC bypass surgery are patients who have a high risk of stroke due to severe narrowing or blockage of the brain arteries and have not responded well to other treatments.
The success of the procedure depends on various factors, such as the extent and location of the blockage, the underlying condition, and the skill and experience of the surgical team.
Potential complications can include infections, bleeding, blood clots, graft failure, and injury to surrounding structures.
The initial study EC/IC bypass study group of 1377 patients found that at 56 months follow-up there was no reduction in the stroke rate between a surgical or medical therapy group.
In a Carotid Occlusion Surgery Study of 195 patients with internal carotid artery occlusion and stage two hemodynamics failure on PET scan were assigned bypass surgery or medical treatment: no benefit of surgery was noted.
In the Carotid and Middle Cerebral artery occlusion surgery study of symptomatic patients treated with EC-IC bypass versus medical therapy in 324 patients, found that the addition of bypass surgery to medical therapy did not significantly change the risk of outcome of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through two years (Ma, Y).