Neuronal migration disorder

Brain MRI, T1 weigthed on a transversal plane, of a 8-month old boy with lissencephaly. Note the scarce and wide gyri, mostly on the parietal, temporal and occipital lobes, the absence of a true Sylvian cissure, and the augmented thickness of the gray matter. The boy had a severe developmental delay and seizures.

Neuronal migration disorder 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.^[1] 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.

Some specific disorders considered as alterations in neuronal migration are lissencephaly, pachygyria, polymicrogyria and focal cortical dysplasia, while the Miller-Dieker syndrome, muscle-brain-eye syndrome, Fukuyama congenital muscular dystrophy and Walker Warburg syndrome are genetic disorders associated with this malformations.^[2]

References

1. ^ Sarnat, Harvey (1992). Cerebral dysgenesis, embryology and clinical expression. New York, US: Oxford University Press. ISBN 0-19-506442-9. 
2. ^ Spalice, Alberto; Pasquale, P; Francesco, N (2009). "Neuronal migration disorders: clinical, neuroradiologic and genetic aspects". Acta Paediatrica 98: 421–433.