click for secret area
Diagnosis and Treatment of ADHD, Learning Disabilities, Migraines, and Traumatic Brain Injury
  • Home
  • Agenesis of the Corpus Callosum

Agenesis of the Corpus Callosum

Overview

Agenesis of the corpus callosum (AgCC) is a congenital disorder characterized by incomplete development of the white matter which connects the two brain hemispheres, called the corpus callosum.  Often diagnosed in the early years, the clinical presentation of AgCC varies widely and encompasses both cognitive and behavioral symptoms. AgCC may be caused by genetic or environmental factors and is often comorbid with other disorders, including autism spectrum disorder and attention issues (1). While AgCC cannot be reversed, there are options for rehabilitation treatment.

 

Symptoms and Prevalence

AgCC is identified as one of the more common brain malformations and has been estimated to occur as 1 per every 4,000 live births (2, 3). Another study provided a prevalence rate of 1.8 per 10,000 births based on data collected over approximately 20 years (1). AgCC is often associated with developmental delays and may overlap with autism spectrum disorder (3). Other psychiatric comorbidities include attention deficit disorder, Tourette syndrome and schizophrenia (3). There also may be comorbid malformations of the nervous system, resulting in various physical symptoms (1).

 

AgCC is a heterogeneous disorder, with varied clinical presentations based on the degree of malformation and associated comorbidities. The primary role of the corpus callosum is to facilitate communication between hemispheres. Typically, when the corpus callosum is severed (as is sometimes done in a surgical procedure for epilepsy treatment), cognitive and motor deficits can emerge. Interestingly, these symptoms do not appear in the same way in those with AgCC, indicating that individuals born with this disorder compensate for a lack of inter-hemispheric communication through other pathways, made possible by the plastic nature of the brain in early years (3). However, those with AgCC often exhibit impaired reasoning for novel situations requiring quick speed of processing (3). Social deficits are commonly observed, including limited social insight and communication (4).  Poor math skills are also common (5).

 

While cognitive impairments are variable, a recent systematic review attempted to characterize the typical neuropsychological profile of AgCC. Results indicated low average to average overall cognitive function, with specific deficits in pragmatic language and math abilities (5). Other cognitive issues were observed in various degrees within domains of receptive and expressive language, visual-spatial skills, attention, and specific executive functions. However, as expected, cognitive profiles were wide-ranging.

 

Diagnosis and Etiology

AgCC is commonly diagnosed in the early years. Due to a degree of false positives using sonogram equipment, it is recommended that magnetic resonance imaging (MRI) scans be used to determine the presence of either partial or complete AgCC (6). Given the heterogeneity of the disorder, prognosis is variable. However, individuals with isolated AgCC (in absence of comorbidities) are thought to have a relatively positive outlook, with some exhibiting a lack notable symptoms (7).

 

Both genetic and environmental factors are implicated in the development of AgCC.  There are numerous genetic anomalies associated with AgCC, reflecting the complexity and heterogeneity of the disorder. Studies have estimated that 30-45% of all diagnosed AgCC cases can be traced back to an identifiable genetic cause (3). These are typically chromosomal rearrangements which may be inherited through autosomal dominant, autosomal recessive, and X-linked pathways (2). Notable environmental factors include exposure to alcohol in utero, with an AgCC incidence rate of 6.8% in those with fetal alcohol syndrome (3). Additional environmental factors include hypothyroidism and post-natal environmental deprivation (3). One study identified advanced maternal age and Black ethnicity (compared to White mothers) as risk factors for AgCC (1).

 

Treatment

The current medical understanding is that AgCC cannot be reversed; but the benefits of rehabilitative treatment have been outlined, with the goal of increasing brain plasticity in order to compensate for associated neurologic deficits. It is recommended that rehabilitation be individualized given the variability within AgCC, and may include speech, physical, cognitive and occupational therapy (8). Additionally, due to common social deficits and interpersonal difficulties, psychotherapy for the individual along with educational training for parents and teachers may help build individual strengths and maximize opportunities for growth (8).  Dr. Thomas is currently planning a program of using neurotherapy to perhaps change and improve the neurophysiology of this disorder in order to help the patient to become functional in daily activities.

— S. Jacobs & J. Thomas

 

References

  1. Glass, H, Shaw, G, Ma, C & Sherr, E (2008) Agenesis of the corpus callosum in California 1983–2003: A population‐based study. American Journal of Medical Genetics Part A, 146(19), 2495-2500.  https://www.ncbi.nlm.nih.gov/pubmed/18642362
  2. Schell‐Apacik, C. C., Wagner, K., Bihler, M., Ertl‐Wagner, B., Heinrich, U., Klopocki, E., … & von Voss, H. (2008). Agenesis and dysgenesis of the corpus callosum: clinical, genetic and neuroimaging findings in a series of 41 patients. American Journal of Medical Genetics Part A, 146(19), 2501-2511.
  3. Paul, L. K., Brown, W. S., Adolphs, R., Tyszka, J. M., Richards, L. J., Mukherjee, P., & Sherr, E. H. (2007). Agenesis of the corpus callosum: genetic, developmental and functional aspects of connectivity. Nature Reviews Neuroscience, 8(4), 287.
  4. Paul, L, Schieffer, B & Brown, W (2004) Social processing deficits in agenesis of the corpus callosum: Narratives from the Thematic Apperception Test. Archives of Clinical Neuropsychology, 19(2), 215-225.
  5. Siffredi, V., Anderson, V., Leventer, R & Spencer-Smith, M. M. (2013). Neuropsychological profile of agenesis of the corpus callosum: a systematic review. Developmental neuropsychology, 38(1), 36-57.
  6. Santo, S., D’antonio, F., Homfray, T., Rich, P., Pilu, G., Bhide, A., … & Papageorghiou, A. T. (2012). Counseling in fetal medicine: agenesis of the corpus https://www.ncbi.nlm.nih.gov/pubmed/23024003
  7. callosum. Ultrasound in Obstetrics & Gynecology, 40(5), 513-521.
  8. Moutard, M, Kieffer, V, Feingold, J, Kieffer, F, Lewin, F, Adamsbaum, C., … & Ponsot, G. (2003) Agenesis of corpus callosum: prenatal diagnosis and prognosis. Child’s nervous system, 19(7-8), 471-476.
  9. Chiappedi, M., & Bejor, M. (2010). Corpus callosum agenesis and rehabilitative treatment. Italian Journal of Pediatrics, 36(1), 64.