Stroke affects about 750 000 people each year in the USA and is a leading cause of long-term adult disability. Over the past decade there have been considerable advances in treatment and prevention. This chapter will review many of these advances with emphasis on issues relevant to surgical patients.
There are two types of stroke: ischemic and hemorrhagic. Ischemic events account for about 80% of all strokes. Most of these are related to atherothromboembolic events.
Atherosclerosis is a systemic disease that most prominently affects the aorta, the coronary arteries, the extracranial carotid and vertebral arteries, and the arteries to the extremities. Atherosclerosis causes stroke by producing progressive stenosis, local thrombosis with occlusion, or distal embolization. Any one of these mechanisms can be the primary cause. For example, progressive atherosclerotic occlusion can cause distal hypoperfusion severe enough to result in tissue ischemia and infarction. Mild or moderate atherosclerotic stenosis that does not cause distal hypoperfusion can be the site of thrombosis and cause intra-arterial embolization leading to occlusion of an intracerebral artery downstream.
The relative significance of local thrombosis versus intra-arterial embolization varies according to the site of atherosclerosis. Most strokes resulting from stenosis of the proximal internal carotid artery are caused by distal embolic occlusion of the middle cerebral artery or its branches. Cerebral infarction in the basilar artery territory usually results from occlusion of the small perforating vessels by local thrombosis.
Ischemic strokes are divided into several categories including cardioembolic, lacunar, and atherosclerotic etiologies.