Corpus Callosum Agenesis: An Insight into the Etiology and Spectrum of Symptoms

Abstract

Brain hemispheres are connected by commissural structures, which consist of white matter fiber tracts that spread excitatory stimuli to various regions of the cortex. This allows an interaction between the two cerebral halves. The largest commissure is the corpus callosum (CC) which is located inferior to the longitudinal fissure, serving as its lower border. Sometimes this structure is not completely developed, which results in the condition known as agenesis of the corpus callosum (ACC). The aim of this paper was to review the latest discoveries related to the genetic and metabolic background of ACC, including the genotype/phenotype correlations as well as the clinical and imaging symptomatology. Due to various factors, including genetic defects and metabolic diseases, the development of CC may be impaired in many ways, which results in complete or partial ACC. This creates several clinical implications, depending on the specificity of the malformation and other defects in patients. Epilepsy, motor impairment and intellectual disability are the most prevalent. However, an asymptomatic course of the disease is even more common. ACC presents with characteristic images on ultrasound and magnetic resonance imaging (MRI).

Keywords: children; clinical symptoms; corpus callosum agenesis; genetic background.

Figure 1

The structures of the human brain in the median plane. Dark blue: corpus callosum.

Figure 2

The ‘racing car sign’ created by enlarged ventricles.

Figure 3

Human brain structures in the medial plane with the septum pellucidum (in color). Dark blue: corpus callosum; light blue: septum pellucidum.