Notes on the Pathology of Cerebral Palsy
Cerebral Palsy (CP) is not a single disease but a heterogeneous group of conditions with brain dammage occuring in utero, at birth, in the neonatal period, or in some instances aquired later in life due to brain injury such as that which one might eccrue in a car accident. CP is the number one cause of physical disability in children. It's exact incidence is uncertain, but there is probably about one case of CP for each 300 births. Males and females are equally affected. There is no racial or familial predisposition.
There are multiple causes of CP. Probably all abnomalities of pregnancy, delivery, and the neoatal period are potential causes of CP. The most frequent cause of CP is anoxia, which may be intrauterine, intrapartum, and/or neonatal. Permanet brian damage resulting from anoxic injury of the term brain is usualy limited to the cerebral cortex (producing spastic cerebral palsy). On the other hand, anoxic injury of the premature brain involves the richly cellular subependymal germinal matrix, from which the entire cerebral hemisphere is developing, and the end result is often extensive loss of grey and/or white matter from the cerebral hemidphere(s). Other causes of CP can include birth trauma, intrauterine infections such as congenital rubella, kernicterus, and neonatal hypoglycemia (caused by intrauterine growth retardation, prematurity, and/or maternal diabetes mellitus). The specific cause of an individule case of cerebral palsy is often uncertain because (1) the intrauterine and intrapartum status of the fetus is difficult to evaluate clinically, (2) the cause of CP may act in utero long before delivery, and (3) details of pregnancy, labor, delivery, and the neonatal period may be forgotten by the time the diagnosis of cerebral palsy is made. Furthermore, several potential causes of CP may coexist. Thus, a traumactic delivery is apt to be complicated by intrapartum fetal anoxia and by protracted neonatal anoxia, and whether the resultant CP is caused by birth truma, anoxia, or both may be unclear.
There is no single brain lesion that is distinctive of cerebral palsy, as might be anticipated from the variety of causes. Many diffrent lesions are found, singly or in various combinations. In genral, the lesions tend to be bilaterally symmetrical and are characterized by loss of neurons and increase of glial cells and fibers (gliosis). Usualy there is obvious loss of tissue in one or more of four sites: the cerebral cortex (resulting in spastic CP), the central white matter of the cerebrum (resulting in spastic CP), the basal ganglia (resulting in athetoid CP), and the cerebellum (resulting in ataxic CP). In the cerebral cortex (spastic CP) the usual lesion is sclerotic microgyria. This is the most frequent lesion in cases of spastic CP. In this lesion individual gyri or groups or gyri are shrunken and firm as a result of loss of neurons and an increase of glial tissue. The sulcal cortex is more severely affected than is the cortex over the gyral crests.
In most but not all cases of cerebral pasly, clinically apparent abnormalities occur during the preceding pregnancy, dilivery, or neonatal period. CP may become apparent in the neonatal period or only after several to many months have passed and the child has not developed normally. The clinical features of cerebral palsy are variable. Three genral clinical syndromes are recognized, corresponding to the predominat site of injury to the brain, but mixtures of symptoms are the rule. The most frequent clinical syndrome, caused by lesions in the cerebral cortex and underlying white matter, is spastic paralysis (spastic cerebral palsy), which accounts for approximatly 50% of all cerebral pasly cases. Spastic CP can be classified into five groups: monoplegia, diplegia, hemiplegia, triplegia, and quadraplegia. Monoplegia is used to discribe when only one limb shows signs of spastic cerebral palsy. Diplegia is used to describe a person who has spastic involvment in two extremities on the same side of the body (ex. left arm and left leg). Hemiplegia is a term used when either both arms or both legs have spastic involvment. Triplegia is used when the patient shows signs of spastic cerebral palsy in only three limbs. Finaly, quadraplegia is used when spastic cerebral palsy affects all four extrimities. The most common type of spastic cerebral palsy is probably diplegia. Monoplegia and Triplegia are extreamly rare is the United States and are almost never used. When the major lesions occur in the basal ganglia, the patient has athetosis (athetoid cerebral palsy). The patient will exibit involuntary movements which may include writhing, grimacing, or jerking. Basal ganglia involvment occurs in about 40% of people with cerebral palsy. It is not subclassified as is the case in spastic cerebral palsy. When lesions occur in the cerebellum the result is ataxic cerebral palsy. Ataxic CP accounts for 10% of persons with CP. Ataxic cerebral palsy is not in any way related to the pathology of inherited ataxias. People with ataxic cerebral palsy have poor balance. For more information about ataxic CP please click on the link to Cerebral Palsy Info Central on the bottom of this page.
Of every seven children born with Cerebral Palsy:
1 dies in infancy;
2 die of recurrent infections in childhood;
1 is of normal mentality, but has severe physical disability
and a short life expectancy;
2 normal mentality and have moderate physical disability
and a normal life expectancy;
1 has normal mentality and slight physical disability with
a normal life expectancy.
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