cerebral palsy, disability caused by brain damage before or during birth or in the first years, resulting in a loss of voluntary muscular control and coordination. Although the exact cause is unknown, apparent predisposing factors include disease (e.g., rubella, genital herpes simplex), very low infant birthweight (less than 3.3 lb [1.5 kg]), and injury or physical abuse. Maternal smoking, alcohol consumption, and ingestion of certain drugs can also contribute. Most cases are associated with prenatal problems; about 10% of the cases are thought to be due to oxygen deficiency during the birth process. The severity of the affliction is dependent on the extent of the brain damage. Those with mild cases may have only a few affected muscles, while severe cases can result in total loss of coordination or paralysis.

There are many different forms of the disability, each caused by damage to a different area of the brain. The spastic type, accounting for over half of the cases, results from damage to the motor areas of the cerebral cortex and causes the affected muscles to be contracted and overresponsive to stimuli. Athetoid cerebral palsy, caused by damage to the basal ganglia, results in continual, involuntary writhing movements. Choreic cerebral palsy is characterized by jerking, flailing movements. Ataxic cerebral palsy, involving the cerebellum, causes either an impaired sense of balance or a lack of coordinated movements. In addition to these types, which may occur singly or together, emotional, visual, and hearing impairments and convulsive seizures may be present. Some of those affected have a degree of mental retardation, but in many the intellect is unimpaired.

There is no cure for the disorder. Treatment usually includes physical, occupational, and speech therapy, and sometimes includes biofeedback and muscle relaxants. Sometimes appliances such as braces and surgery are helpful. Measures that appear to help decrease the incidence of cerebral palsy include maternal immunization against rubella, maternal abstention from smoking and alcohol consumption, magnesium sulfate given in premature labor, treatment for Rh incompatibility (see blood groups), and treatment of hyperbilirubinemia (jaundice) in the newborn.

or cerebrovascular accident (CVA)

Sudden impairment of brain function due to hypoxia, which may cause death of brain tissue. Hypertension, atherosclerosis, smoking, high cholesterol, diabetes, old age, atrial fibrillation, and genetic defects are risk factors. Strokes due to thrombosis (the most common cause), embolism, or arterial spasm, which cause ischemia (reduced blood supply), must be distinguished from those due to hemorrhage (bleeding), which are usually severe and often fatal. Depending on its site in the brain, a stroke's effects may include aphasia, ataxia, local paralysis, and/or disorders of one or more senses. A massive stroke can produce one-sided paralysis, inability to speak, coma, or death within hours or days. Anticoagulants can arrest strokes caused by clots but worsen those caused by bleeding. If the cause is closure of the major artery to the brain, surgery may clear or bypass the obstruction. Rehabilitation and speech therapy should begin within two days to retain and restore as much function as possible, since survivors may live many more years. Transient ischemic attacks (“mini strokes”), with short-term loss of function, result from blockage of blood flow to small areas. They tend to recur and may worsen, leading to multi-infarct dementia or stroke.

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Paralysis resulting from abnormal development or damage to the brain before or soon after birth. Cases are of four main types: spastic, with spasms contracting the extremities and often also with intellectual disability and epilepsy; athetoid, with slow, changing spasms in the face, neck, and extremities, grimacing, and inarticulate speech (dysarthria); ataxic, with poor coordination, muscle weakness, an unsteady gait, and difficulty performing rapid or fine movements; and mixed, in which symptoms of two or more types are present.

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