Question
I have a niece who has been diagnosed with agenesis of the corpus callosum. I would like to know what effects this may have on her language performance, written and oral. She is six years old now, and she doesn't seem to have any problems yet.
Answer
By definition agenesis of the corpus callosum, the largest neural tract between the two hemispheres, indicates the individual was born without a corpus callosum. In truth, however, this term is often used to describe partial absence of the corpus callosum as well.
To better understand how agenesis of the corpus callosum affects your niece, it is important to know if the corpus callosum is absent or partially spared. Specific skills correspond with each section of the corpus callosum. The anterior section transfers tactile information and is associated with seizure discharges. The middle third transfers visuo-spatial information. The posterior section transfers visual information, bimanual coordination, and sensorimotor integration.
Interestingly, the corpus callosum is not the only pathway between the hemispheres. There are two smaller pathways, the anterior commissure and the posterior commissure that develop slightly before the corpus callosum. There are several reasons your niece "does not seem to have any problems yet." One theory holds that the anterior commissure assumes a major role in transferring information when the corpus callosum is unable to do so. A second theory suggests when the fibers are unable to cross through the absent or partial corpus callosum, they reverse and connect with other fibers in the same hemisphere. The third hypothesis contends each hemisphere can be independent of the other.
As these theories apply to your niece, increased response delays and shortened attention span are likely. She might also display visuo-motor difficulties (e.g., difficulty copying from the board in school) and/or fine motor problems. In general, those affected tend to make more mistakes and experience word recall difficulty. Because the most commonly reported problem among those whose neural pathways are disturbed is epilepsy, be alert for signs of seizure behavior.
When a problem arises in the developing brain, new and alternate neural pathways are created often without obvious differences in performance. The plasticity of the brain in infants and young children is truly amazing.
Please visit the SpeechPathology.com Library to learn more about this topic and to view a variety of live, recorded and text-based courses in the field.
Dr. Karen E. Crockett has extensive clinical experience evaluating and treating children with a diverse array of developmental disabilities. During the past 18 years, she has developed many individually tailored treatment strategies and approaches in her private practice. Dr. Crockett credits a great deal of her success to working closely with the families of the children she treats and thereby understanding the unique needs of each child.