Neuronal migration disorder (NMD)

81 years old female patient
Clinical symptoms: Epileptic seizures and mild cognitive decline
Brain MRI: White mater Ectopias

Neuronal migration disorder (NMD) refers to a heterogenous group of disorders that, it is supposed, share the same etiopathological mechanism: a variable degree of disruption in the migration of neuroblasts during neurogenesis. The neuronal migration disorders are cerebral dysgenesis, brain malformations caused by primary alterations during neurogenesis; on the other hand, brain malformations are highly diverse and refer to any insult to the brain during its formation and maturation due to intrinsic or extrinsic causes that ultimately will alter the normal brain anatomy. However, there is some controversy in the terminology because virtually any malformation will involve neuroblast migration, either primarily or secondarily.

More than 25 syndromes resulting from abnormal neuronal migration have been described. Among them are syndromes with several different patterns of inheritance; genetic counseling thus differs greatly between syndromes.

• Lissencephaly
• Schizencephaly
• Porencephaly
• Pachygyria
• Polymicrogyria
• Agyria
• Macrogyria
• Microgyria
• Micropolygyria
• Neuronal heterotopias
• Agenesis of the corpus callosum
• Agenesis of the cranial nerves
• Band heterotopias

Focal cortical dysplasia. Miller-Dieker syndrome, muscle-brain-eye syndrome, Fukuyama congenital muscular dystrophy and Walker Warburg syndrome are genetic disorders associated with lissencephaly.

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