Cerebral palsy refers abnormal motor function from brain injury that occurs early in development. The cause of cerebral palsy is unclear for most cases, but many of these patients may have some form of vascular injury to motor areas of the developing brain, most commonly affecting upper motor neurons. The onset is congenital, but deficits gradually become apparent in the first few years of life with delays in motor milestones. The course usually consists of stable motor abnormalities after development. Some of these patients will also have intellectual disability of varying degrees or abnormalities of other neural functions, but many will have only motor abnormalities.
The most common types of cerebral palsy are called spastic diplegia and spastic quadriplegia. The term spastic in this context refers to upper motor neuron abnormalities, which often includes spasticity. The term plegia in this context is often a misnomer: some of these patients with have paralysis, but many will have less severe weakness or no weakness. Spastic diplegia consists of upper motor neuron abnormalities that involve both legs more than the arms. This is strongly associated with preterm birth, which is a population at increased risk for cerebral palsy and other types of early brain injury. Spastic quadriplegia consists of upper motor neuron abnormalities that are similar in all four limbs, which is more often seen with full term births.