the subarachnoid space, or 4) the late stage organization of the neuronal layer in the cortex is disrupted. Abnormal migration ultimately results in abnormal gyral formation. Diagnosis Types of NMD syndromes 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 Microlissencephaly Schizencephaly Porencephaly Pachygyria Polymicrogyria Agyria Macrogyria Microgyria Micropolygyria Grey matter heterotopia Agenesis of the corpus callosum Agenesis of the cranial nerves Band heterotopias Focal cortical dysplasia, Miller–Dieker syndrome, , Fukuyama congenital muscular dystrophy and Walker–Warburg syndrome are genetic disorders associated with lissencephaly. Treatment Treatment is symptomatic and may include anti-seizure medication and special or supplemental education consisting of physical, occupational and speech therapies. Prognosis The prognosis for children with NMDs varies depending on the specific disorder and the degree of brain abnormality and subsequent neurological signs and symptoms. References Neurological disorders