The corpus callosum — the largest white-matter structure in the brain — connects the left and right hemispheres. Agenesis of the corpus callosum (AgCC) is a condition in which the structure is partly or completely missing, severely limiting integration of left-brain and right-brain function.
AgCC is rare, occurring in just one in 4,000 individuals. It may occur alone or with other cerebral abnormalities. Approximately three to five percent of children diagnosed with neurodevelopmental disabilities have AgCC. Up to 75 percent are male; however, AgCC is also a feature of Aicardi’s syndrome, a severely disabling genetic disorder that occurs almost exclusively in females.
Symptoms of AgCC may range from mild to severe. Children may demonstrate normal intelligence with some compromise in specific skills, or they may be hydrocephalic, have substantial retardation, and suffer seizures and spastic episodes. AgCC is also associated with physical malformations, including midline facial defects.
Neuroanatomically, AgCC will neither improve nor worsen, and it is rarely life threatening. However, it is common to see an increase in symptoms as an individual with AgCC moves from childhood into adolescence. This change is due to their peers’ improvements in skills such as abstract thought and social insight, and their own relative impairments in these areas. Treatment usually consists of learning to deal with specific symptoms and managing seizures if they occur. Although the challenges of living with AgCC are often significant and lifelong, patients are frequently able to lead meaningful and productive lives.
Because AgCC is rare and is associated with a wide and varying range of symptoms, patients frequently are not diagnosed, or they may be incorrectly diagnosed with ADHD, Asperger’s Syndrome, psychiatric disorders, or other disorders. Accurate diagnosis of abnormalities of the corpus callosum, including AgCC, requires a brain scan (preferably an MRI).
Developmental Problems in AgCC
Developmental milestones such as walking, talking, and reading are typically delayed to a varying extent in children with AgCC. Motor skills, especially those involving left-right coordination (for example, swimming or tying shoes) may be a particular challenge. People with AgCC may have heightened sensitivity to some sensory cues such as certain types of touch or food textures, yet they typically have a high tolerance for pain.
Development of young children with AgCC may be similar to that of other children; however, social or problem-solving skills typically do not improve as they go through elementary school. Normally, the corpus callosum matures and becomes more efficient as children approach adolescence, allowing abstract reasoning, problem solving, and socialization to develop rapidly. This does not occur in children with AgCC; consequently, they fall behind their peers mentally and socially as they proceed through their teens and into adulthood.
People with AgCC may be oblivious to the social consequences of their own behavior and typically do not pick up on the social cues of others. They may fail to comprehend jokes or figures of speech, tending instead to interpret communication literally. They are also not as effective as their peers in recognizing emotion in people’s faces, and they are often extremely gullible.
Caring for People with AgCC
Even patients in whom the corpus callosum is totally missing develop a rudimentary compensatory system, providing them with some interaction between the left and right brain hemispheres. Starting a child early with behavioral and cognitive training can help to maximize his or her abilities.
Neuropsychological testing is a necessary tool for evaluating a patient’s cognitive skills. Each patient has unique needs, so it is important to work with teachers, specialists in learning disabilities, and other professionals to develop an Individualized Education Program (IEP). Because of their deficits in social and cognitive skills, patients must be educated about their condition and given consistent direct feedback. Constant repetition is essential for them to learn new material.
It is also very important for caregivers to network with each other. Networking provides a means of sharing ideas and experience, and also establishes a way to coordinate efforts to raise awareness of AgCC throughout the community and health and educational systems.
The National Organization for Disorders of the Corpus Callosum is a nonprofit corporation established in 2002 by professionals, parents, and individuals with corpus callosum disorders. Their mission is to enhance the quality of life and promote opportunities for individuals with disorders of the corpus callosum and raise the profile, understanding, and acceptance of these disorders through research, education, advocacy, and networking.
For more information on AgCC, visit the National Organization for Disorders of the Corpus Callosum Web site at www.nodcc.org.