The term cerebral palsy refers to any one of a number of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination but don't worsen over time. Even though cerebral palsy affects muscle movement, it isn't caused by problems in the muscles or nerves. It is caused by abnormalities in parts of the brain that control muscle movements. The majority of children with cerebral palsy are born with it, although it may not be detected until months or years later. The early signs of cerebral palsy usually appear before a child reaches 3 years of age. The most common are a lack of muscle coordination when performing voluntary movements (ataxia); stiff or tight muscles and exaggerated reflexes (spasticity); walking with one foot or leg dragging; walking on the toes, a crouched gait, or a "scissored" gait; and muscle tone that is either too stiff or too floppy. A small number of children have cerebral palsy as the result of brain damage in the first few months or years of life, brain infections such as bacterial meningitis or viral encephalitis, or head injury from a motor vehicle accident, a fall, or child abuse.
Cerebral palsy is caused by damage to the motor control centers of the developing brain and can occur during pregnancy, during childbirth or after birth up to about age three. Resulting limits in movement and posture cause activity limitation and are often accompanied by disturbances of sensation, depth perception and other sight-based perceptual problems, communication ability, and sometimes even cognition; sometimes a form of CP may be accompanied by epilepsy. CP, no matter what the type, is often accompanied by secondary musculoskeletal problems that arise as a result of the underlying etiology.
Of the many types and subtypes of CP, none of them has a known cure. Usually, medical intervention is limited to the treatment and prevention of complications arising from CP's effects. A 2003 study put the economic cost for people with CP in the US at $921,000 per individual, including lost income. In another study, the incidence in six countries surveyed was 2.12-2.45 per 1,000 live births, indicating a slight rise in recent years. Improvements in neonatalology, or the medical specialty which is involved with treatment of neonates, have helped reduce the number of babies who develop cerebral palsy, but the survival of babies with very low birth weights has increased, and these babies are more likely to have cerebral palsy.