DEFINITION AND ETIOLOGY

A stroke is defined as an acute loss of neurological function due to an abnormal perfusion of brain tissue. Most strokes are ischemic (87%) in nature and commonly result from an arterial obstruction by a thrombus or embolus. Hemorrhagic strokes (13%) are caused by rupture or leak of a blood vessel either within the primary brain tissue or subarachnoid space. This chapter provides a clinical approach to the evaluation and management of stroke, with a focus on ischemic stroke.

PREVALENCE AND RISK FACTORS

Because stroke is the leading cause of morbidity and the third-leading cause of death in the United States today, optimal reduction of risk factors is paramount in preventing and managing stroke. Modifiable and nonmodifiable stroke risk factors are listed in Table 1. In 2005, the prevalence of stroke in noninstitutionalized adults was 5.8 million in the United States alone. Based on American Stroke Association data, the estimated direct and indirect cost of stroke for 2008 was $65.5 billion, with an estimated lifetime cost of $140,000 per patient.

Table 1 Cerebrovascular Disease Risk Factors

PATHOPHYSIOLOGY AND NATURAL HISTORY

SIGNS AND SYMPTOMS

An acute stroke is signified by a sudden onset of focal neurologic deficit and is variable depending on the area of tissue ischemia. Localization can often be made by the pattern of clinical findings. Common stroke syndromes are listed in Table 2 according to vascular distribution. Although headache might accompany an ischemic stroke, an acute and severe headache that is maximal at onset more commonly represents a subarachnoid or intraparenchymal hemorrhage, especially if this is followed by somnolence or decreased mental status. Seizures can also occur at the onset of ischemic or hemorrhagic strokes.

Table 2 Overview of Selected Stroke Syndromes

Motor symptoms consist of facial droop, hemiparesis, or isolated weakness of the arm or leg. Dizziness, slurred speech, problems with coordination, or difficulty with gait and balance may also be reported and may be due to involvement of cerebellar fibers. Sensory symptoms include numbness or altered sensation, with tingling paresthesias of one side of the body or face, or both. Vision loss in one eye or both eyes as in a homonymous hemianopsia can also occur.

Patients with an acute stroke might also present with confusion or are sometimes perceived as being confused when there is an expressive or receptive aphasia or a visuospatial neglect phenomenon.

One of the most urgent and potentially devastating stroke syndromes is thrombosis of the basilar artery, which can manifest with acute quadriparesis, loss of consciousness, and respiratory failure.