Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

Abstract

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

Fig. 1

Fractional anisotropy maps of mid-sagittal corpus callosum with overlay of all discernable fibers projecting out to specific cortical areas. Four female subjects on right and four male subjects on left. Color-scheme of projections is as follows: prefrontal lobe (green), premotor and supplementary motor areas (light blue), primary motor cortex (dark blue), primary sensory cortex (red), parietal lobe (orange), occipital lobe (yellow), and temporal lobe (violet). Extracted from Fig. 2 in (Hofer and Frahm 2006)

Fig. 2

Examples of mid-sagittal MRI images and statistical outcomes from several of the conditions described in this review. All images are oriented with anterior to the left; a complete AgCC; b partial AgCC; c statistical significance of smaller CC area in 22qDS than controls (Fig. 4d in (Machado et al. 2007)); d CC hypoplasia in an individual born preterm (Fig. 2 in (Nosarti et al. 2004)); e significance of mean local CC area reveals significantly smaller anterior third of callosum in autistic subjects relative to control subjects (Fig. 2c in (Vidal et al. 2006))