Neuronal migration disorders (NMD) are developmental malformations of the cerebral hemispheres, frequently associated with severe epilepsy. They can be defined as cerebral malformations characterised by malpositioning and faulty differentiation of cortical grey matter. Neuronal positioning is an integral part of the coordinated steps comprising neural circuit formation in embryonic and neonatal development. Correct positioning of neurons by normal migration plays a critical role in establishing cognitive functions and emotion. The causes of brain malformations associated with positioning and migration defects are varied and include genetic mutations and environmental toxins. Studies of neuronal migration disorders have progressed due to advances in molecular genetics and brain magnetic resonance imaging.
