Definition of Agenesis of the corpus callosum

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Agenesis of the corpus callosum: A congenital abnormality (a birth defect) in which there is partial or complete absence (agenesis) of the corpus callosum, the area of the brain which connects the two cerebral hemispheres (the two halves of the brain).

Agenesis of the corpus callosum can occur as a severe syndrome in infancy or childhood, as a milder condition in young adults, or as an asymptomatic incidental finding.

If there are symptoms, the first ones are usually seizures followed by feeding problems and delays in holding the head erect, sitting, standing, and walking. The seizures may constitute a very common disorder called infantile spasms. There may also be retardation in mental and physical development and impairment of hand-eye coordination and visual and auditory memory. Hydrocephalus is also a complication. In mild cases, symptoms (such as seizures, repetitive speech, and/or headaches) may not appear for years.

Girls with agenesis of the corpus callosum may have a specific condition called Aicardi's syndrome in which there is severe mental retardation, infantile spasms and chorioretinal lacunae. Agenesis of the corpus callosum can occur as an isolated condition or in association with other cerebral anomalies (such as the Arnold-Chiari malformation and Dandy-Walker syndrome, Andermann syndrome with progressive neuropathy, schizencephaly, holoprosencephaly, and migrational anomalies). Agenesis of the corpus callosum is also associated with several chromosome anomalies, including trisomy 13 and trisomy 18.

There is no standard course of treatment for agenesis of the corpus callosum. Treatment usually involves management of signs and symptoms such as hydrocephalus and seizures if they occur.

The prognosis (outlook) with agenesis of the corpus callosum is variable. The condition does not cause death in the majority of patients. Although many children with the disorder lead normal lives and have average intelligence, careful neuropsychological testing reveals subtle differences in higher cortical function compared to individuals of the same age and education without ACC. Children with agenesis of the corpus callosum accompanied by developmental delay and/or seizure disorders should be screened for metabolic disorders. The mental retardation associated with agenesis of the corpus callosum is not progressive.