One subtype of spastic diplegia is associated with a relatively slight diminution in head size and of intelligence. As indicated above, there is no unifying neuropathology; the condition occurs independently of matrix hemorrhages and periventricular leukomalacia as well as with them. The frequency of cerebral spastic diplegia, which is closely related to the degree of prematurity, has declined significantly since the introduction of neonatal intensive care facilities, and there is reason to believe that genetic factors are of more importance.
Infantile hemiplegia and quadriplegia Hemiplegia is a common condition of infancy and early childhood. The functional difference between the two sides may be noticed soon after birth, but more often it is not perceived by the mother until after the first 4 to 6 months of life. In a second group, the child is in excellent health for a year or longer before the abrupt onset of hemiplegia (see below). In hemiplegia that dates from earliest infancy—that is, congenital hemiplegia—the parents first notice that movements of prehension and exploration are carried out with only one arm. A manifest hand preference at an early age should always raise the suspicion of a unilateral motor defect. The affection of the leg is usually recognized later, that is, during the first attempts to stand and walk. Sitting and walking are usually delayed by a few months. In the older child, there is evident hyperactivity of tendon reflexes and usually a Babinski sign. The arm is held flexed, adducted, and pronated, and the foot assumes an equinovarus posture. Sensory and visual field defects can be detected in some patients. Cognitive slowing may be associated with infantile hemiplegia but is less common and lesser in degree than with cerebral diplegia. There may also be speech delay, regardless of the side of the lesion; when this is present, there is usually developmental delay and bilaterality of motor abnormality. Convulsions occur in 35 to 50 percent of children with congenital hemiplegia, and these may persist throughout life. They may be generalized but are frequently unilateral and limited to the hemiplegic side (or the contralateral side if the hemiplegia is severe). After a series of seizures, the weakness on the affected side will be increased for several hours or longer (Todd paralysis). Gastaut and associates have described a hemiconvulsive–hemiplegic syndrome in which progressive paralysis and cerebral atrophy are attributed to the convulsions. As months and years pass, the osseous and muscular growth of the hemiplegic limbs is impeded, leading to an obvious hemiatrophy of the body.
With respect to the causation of congenital hemiplegia, it is generally agreed that perinatal asphyxia is only one of the possibilities. In the series of 681 children with “cerebral palsy” collected by Hagberg and Hagberg, there were 244 with hemiplegia of whom 189 were full-term babies and 55 were preterm. Prenatal risk factors were identified in only 45 percent, and mostly in the infants born prematurely. In nearly half of the cases, there was no clue as to the time in the intrauterine period when the cerebral lesion occurred.