Arterial lesions capable of producing transient episodes of cerebral dysfunction due to cerebrovascular insufficiency or the more lasting lesion, a brain infarct, may be found at any level of either the carotid or vertebral systems. Lesions of the extracranial portions of these systems have come under particular attention because their surgical relief plays a part in the prevention and perhaps the relief of strokes. By far the most commonly encountered stenosing lesion of the cerebral arterial supply amenable to surgical relief is that located at the carotid bifurcation.
The symptoms produced by this particular lesion are widely varied, in both type and duration. Most commonly, however, they are intermittent and transient. General mental deterioration suggests that diffuse intracranial arterial disease is present in addition to the extracranial arterial stenosis. When the cerebral deficit is lasting rather than transient, a total occlusion is likely to be present. The severity of the