Neuronal Migration Disorder

neuronal migration disorder

This child presented with seizures. The coronal true inversion recovery sequence shows thickened and disordered cortex in superior frontal and cingulate gyri bilaterally (arrow). There are small convolutions visible at the corticomedullary junction. The appearance is that of cortical dysplasia, with polymicrogyria more likely than pachygyria due to the small convolutions visible (it can be very hard to tell without handing the brain to a pathologist). There are also small foci of grey matter signal in the corpus callosum, deep to the dysplastic cortex (double arrows). These probably represent areas of grey matter heterotopia.

Neuronal migration disorders are thought to occur due to arrest of movement of the developing neuroblasts from the germinal centres (periventricular) to the cortex. They manifest as heterotopic grey matter, sulcation abnormalities, pachygyria, polymicrogyria, megalencephaly, or focal cortical dysplasia. This may occur due to genetic abnormalities (X-linked lissencephaly, Fukuyama muscular dystrophy, and Walker-Warburg syndrome, to name a few) or intrauterine insults such as infections (eg cytomegalovirus). These patients present with seizures, developmental delay, or spastic paresis.

Reference: Grossman RI, Yousem DM. Neuroradiology: The Requisites. 2nd ed. Mosby 2003.

Credit: Dr Laughlin Dawes