Major causes of stroke include cerebral thrombosis, embolism, and hemorrhage.

Thrombosis is the most common cause of stroke in middle-aged and elderly people. Stroke results from obstruction of a blood vessel. Typically, the main site of the obstruction is the extracerebral vessels, but sometimes it’s intracerebral.

Embolism, the second most common cause of stroke, can occur at any age, especially among patients with a history of rheumatic heart disease, endocarditis, posttraumatic valvular disease, myocardial fibrillation and other cardiac arrhythmias, or after open-heart surgery. It usually develops rapidly—in 10 to 20 seconds and without warning. Most often the left middle cerebral artery is the embolus site.

Hemorrhage, the third most common cause of stroke, may also occur suddenly at any age. Such hemorrhage results from chronic hypertension or aneurysms, which cause sudden rupture of a cerebral artery.

Factors that increase the risk of stroke include a history of TIAs, atherosclerosis, hypertension, arrhythmias, electrocardiogram changes, rheumatic heart disease, diabetes mellitus, gout, postural hypotension, cardiac enlargement, high serum triglyceride levels, lack of exercise, use of oral contraceptives, smoking, and a family history of cerebrovascular disease.

Among the many possible complications of stroke are unstable blood pressure from loss of vasomotor control, fluid imbalances, malnutrition, sensory impairment such as vision problems, and infection, such as encephalitis, brain abscess, and pneumonia. Altered level of consciousness
(LOC), aspiration, contractures, and pulmonary emboli may also occur.

Clinical features of stroke vary with the artery affected (and, consequently, the portion of the brain it supplies), the severity of the damage, and the extent of collateral circulation that develops to help the brain compensate for decreased blood supply.

When assessing a patient who may have experienced a stroke, remember this: If the stroke occurs in the left hemisphere, it produces signs and symptoms on the right side; if it occurs in the right hemisphere, signs and symptoms appear on the left side. However, a stroke that causes cranial nerve damage produces signs of cranial nerve dysfunction on the same side as the hemorrhage or infarct.

The patient’s history, obtained from a family member or friend if necessary, may uncover one or more risk factors for stroke. The history may also reveal either a sudden onset of hemiparesis or hemiplegia or a gradual onset of dizziness, mental disturbances, or seizures. The patient or a family member may also report that the patient lost consciousness or suddenly developed aphasia. Speaking with the patient during history taking may reveal communication problems, such as dysarthria, dysphasia or aphasia, and apraxia.

Neurologic examination identifies most of the physical findings associated with stroke. These may include unconsciousness or changes in LOC, such as a decreased attention span, difficulties with comprehension, forgetfulness, and a lack of motivation. If conscious, the patient may exhibit anxiety along with communication and mobility difficulties. Inspection may reveal related urinary incontinence.

Motor function and muscle strength tests often show a loss of voluntary muscle control and hemiparesis or hemiplegia on one side of the body. In the initial phase, flaccid paralysis with decreased deep tendon reflexes may occur. These reflexes return to normal after the initial phase, along with an increase in muscle tone and, in some cases, muscle spasticity on the affected side.

Vision testing often reveals hemianopia on the affected side of the body and, in patients with left-sided hemiplegia, problems with visual-spatial relations.

Sensory assessment may reveal sensory losses, ranging from slight impairment of touch to the inability to perceive the position and motion of body parts. The patient may also have difficulty interpreting visual, tactile, and auditory stimuli. (See Reviewing neurologic deficits in stroke.)