Natural History of Patients with Chronic Occlusion of the Internal Carotid Artery

Although 3% of the elderly population may have asymptomatic unilateral internal carotid artery occlusion (ICAO), between 10% and 20% of patients with initial stroke in the carotid territory have appropriate ipsilateral extracranial ICAO. In the latter instance, it is often difficult to establish whether ICAO is (a) an acute thrombotic process on an underlying atheromatous stenosis; (b) an acute embolic ICAO (from heart or aorta); or (c) an old ICAO that was previously asymptomatic. Intracranial studies show that the first stroke ipsilateral to ICAO is usually associated with occlusions distal to ICAO, which suggest artery-to-artery embolism. On the other hand, the follow-up of stroke patients with ICAO shows that delayed cerebral infarction distal to the established ICAO often involves watershed areas and may correspond to hemodynamic disturbances. Because the international extracranial/intracranial arterial bypass study did not show any surgical benefit, current management is mainly directed to stabilization of associated causes of hemodynamic failure (hypotension, bradycardia, etc.). Attempts to find subgroups that may benefit from bypass surgery are still ongoing. However, the prognosis of these patients is negatively influenced by a particularly high risk of cardiac death.