The prevalence of cerebral palsy has remained very stable for many years at this percentage. While the improved survival of extremely preterm infants may result in an increasing number of children with cerebral palsy, preemies constitute a small minority of the overall number of disabled children. The diagnosis of cerebral palsy means that there has been some injury to the brain during development which has resulted in difficulty transmitting impulses from the brain to the muscles, disrupting coordinated movement.
Cerebral palsy comes in a variety of forms and with a continuum of severity.
It can be so mild that it is only noticeable when the individual is stressed or involved in certain activities. It can be so severe as to limit most voluntary movement. It can take several years for the full impact of a child's cerebral palsy to become apparent. However, children do not switch from one form of cerebral palsy to another, nor from one impairment level to another, after the condition is fully expressed. Children who have mild motor impairment and who are suspected of cerebral palsy at one year of age are often free of motor symptoms by early school age.