spastic paralysis, form of paralysis in which the part of the nervous system that controls coordinated movement of the voluntary muscles is disabled. In spastic paralysis the nerves controlling muscle movement are hyperirritable and do not function in a coordinated manner, so that impulses from them cause spasmodic muscle contraction. Extreme spastic paralysis occurs after various kinds of brain damage, e.g., stroke. Spinal cord injury, such as that produced by inflammatory diseases of nerve tissue, can injure motor neuron fibers in the spine and cause spastic paralysis. Congenital spastic paralysis, or cerebral palsy, is often a result of intrauterine disease or birth injury, or occasionally some inherited nervous system defect.