SYMPTOMS
A
stroke may be mildly incapacitating, massive with
sudden death, or may involve a sudden coma, followed by headache, nausea, confusion, and stupor. The symptoms of a stroke are sudden weakness or numbness of the face or limbs on one side of the body (hemiplegia); loss of speech or comprehension; dimness or loss of vision, particularly in one eye; and unexplained dizziness, unsteadiness, or sudden falls. Some
strokes are preceded by TIAs, with similar effects that may last anywhere from one minute to several hours. Initially, the paralyzed muscles of a stroke victim are soft because of central nervous system shock, but spasticity occurs as spinal
motor neurons resume function, tightening muscles and causing the limbs to contract.
TYPES OF STROKES
Ischemia A stroke can be caused by ischemia, which is a narrowing or blockage of an
artery by means of atherosclerosis or by an embolus. About 65% of strokes are ischemic. Atherosclerosis, or progressive hardening of the arteries, produces ischemia by obstruction of vessels with fat derivatives. Most frequently, cholesterol forms plaques that build up on arterial walls, reducing the passage of blood. A common aging process, atherosclerosis especially afflicts the elderly or people with high cholesterol intake.
Another form of ischemia is thrombosis, or blockage resulting from an embolus. An embolus produced by the carotid artery in the neck, which supplies blood from the heart to the brain, claims about one-third of stroke patients. A clot, or thrombus, can form in this artery and fragment, producing a thromboembolus, which travels to the brain and becomes entrapped in a cerebral artery.
Hemorrhage About 20% of all strokes are caused by cerebral hemorrhage. Causes of spontaneous intracranial hemorrhage are hypertension (10% to 15% of all cases), aneurysm (5% to 7%), bleeding into a tumor (3% to 5%), and a generalized bleeding tendency (1% to 2%). Hypertensive hemorrhages occur in the brain stem or the lateral portion of the cerebral hemisphere near the pathway for motor nerves; if the hemorrhage extends into the motor tract, hemiplegia will result. A massive hemorrhage, however, can result in coma, brain damage, and possibly death. Alcoholics, who bleed more easily, are more likely to have this type of stroke.
AneurysmsÑenlargements of small portions of blood vesselsÑcan hemorrhage and cause stroke if present in the brain or arteries of the neck. Rupture of an aneurysm can cause massive bleeding on the surface of the brain and may be fatal. After an aneurysm ruptures, red blood cells degenerate and release products that promote vascular spasm. An aneurysm is usually treated surgically after a two-week waiting period, which allows edema and vasospasm to subside. Often, however, bleeding begins again and is frequently fatal.
Tumors must have an adequate blood supply to maintain their growth; therefore some tumors secrete an angiogenesis factor that promotes blood-vessel growth. At times a tumor may produce too much of this factor, causing the vessels to enlarge. This enlargement can result in internal hemorrhage and sudden stroke. The stroke, unfortunately, may mask the existence of a tumor and delay a complete diagnosis.
DIAGNOSIS
The most important information is history from the patient or a witness. A neurological examination shows what parts are not functioning properly, which can point to the probable damaged location in the brain, and often the probable cause. Diagnostic techniques for stroke include injecting radiopaque dyes into vessels of the neck and head (arteriogram), using brain scans for defects in the blood/brain barrier, conducting a magnetic resonance scan, and performing computerized tomography (see CAT scan) with image enlargement to search for altered density within the brain. Lumbar puncture (spinal tap) is usually not necessary and may do more damage in some types of strokes.
TREATMENT
The medical team involved in caring for stroke victims includes an internist, a neurosurgeon, a neurologist, a stroke nurse, a physical therapist, an occupational therapist, and a speech therapist. These people also help educate the patient's family in long-term care as well as alerting them to problems that may be encountered during rehabilitation.
The type of treatment depends on the type of stroke. For example, a patient with a stroke caused by hypertension needs to have his or her blood pressure reduced significantly. Physiotherapy is an important part of medical treatment for stroke patients, to rehabilitate the damaged functions and preserve the motor abilities of contracted limbs. Speech and occupational therapists can help in the recovery of motor functions. Medical complications are also treated, with an emphasis on preventing a recurrence.
Debility is often severe, and depression may occur. Stroke support groups are an important resource for helping the stroke patient learn ways of coping with disability. Research is focusing on ways to limit brain damage, such as by using drugs to dissolve blood clots in ischemic strokes, and to prevent the death of brain cells.
More abstracts about the STROKES