Agenesis Of Corpus Callosum

Patient Education

What is the Corpus callosum?

The corpus callosum, with about 200 million axons, is the largest white matter tract in the brain. It plays a key role in the integration and transfer of information between the two cerebral hemispheres.

The corpus callosum is divided into four parts from anterior to posterior: rostrum, genu, body, and splenium.

It is formed between 8 to 20 weeks of gestation, with myelination continuing till early adulthood. The anterior body develops first and then continues bidirectionally, the rostrum appears last.

Hence, if the rostrum is visible on a scan, it can be said that the rest of the corpus callosum has developed normally.

What is Corpus callosum dysgenesis?

Corpus callosum anomaly may be :
Primary – partial or complete absence of the corpus callosum (CCA). It can occur as an isolated condition or in combination with other brain abnormalities.

Secondary – dysgenesis of the corpus callosum - may be complete or partial. This may occur due to encephalomalacia following an ischemic, metabolic, or traumatic insult.

Recent studies suggest that CCA is part of a cerebral malformation spectrum, particularly midbrain-hindbrain development.

Some conditions with corpus callosum anomaly:

• Chiari II malformation
• Dandy-Walker spectrum
• Septo-optic dysplasia
• Aicardi syndrome
• Fetal Alcohol syndrome
• Prematurity

Metabolic disorders:

• Disorders of oxidative phosphorylation
• Pyridoxine -dependent epilepsy
• Non-ketotic hyperglycinemia

MRI features

• In CCA, the white matter tracts called Probst bundles,which usually cross the midline are instead oriented vertically, separating the lateral ventricles widely, in a racing car sign configuration.
• The hippocampal formations are usually hypoplastic
• Colpocephaly - dilatation of the temporal and occipital horns of the lateral ventricles, giving rise to moose head/viking helmet appearance on coronal imaging.
• Absent septum pellucidum
• Widened interhemispheric fissure
• Dilated, dorsally displaced third ventricle

What are signs and symptoms of CCA?

There is a wide spectrum of clinical presentation, depending on

• Corpus callosum that is partially or completely absent
• Presence of other brain abnormalities

Children with isolated CCA may seem to have normal development and functioning. However, neuropsychological testing in these children has revealed higher function deficits.

Most common features include:

• Poor motor co-ordination, delayed motor milestones
• Fine motor issues
• Seizures
• Intellectual disability

Relevant neuropsychological deficits seen with CCA -

1. Impairment of abstract reasoning
2. Problem solving
3. Feeding or sleep issues
4. Unusual tolerance for pain
5. Impaired social skills
6. Unable to understand and display emotions well

Investigations include:

• Structural brain abnormalities are diagnosed by MRI or CT scan, prenatal ultrasound, or prenatal MRI.
• Neuropsychological testing
• Eye check

What is the treatment for CCA?

There are no specific treatments for CCA.

Most patients will require and benefit from multidisciplinary care -

• Neurologist
• neurodevelopmental pediatrician
• psychologist
• occupational therapist, physiotherapist, speech and language therapist
• geneticist
• ophthalmologist

What is the Prognosis for CCA?

Prognosis depends on the extent and severity of malformations. While most individuals with isolated CCA can lead full lives, neuropsychological deficits should be identified in order to get the required support and services and thus enable them to maximize their full potential.