The role of pre-, peri-, and postnatal environmental factors and genetic predisposition in the genesis of neuronal migration disorders (NMD) in 40 patients with epilepsy was determined by standardized questionnaires at the Montreal Neurological Institute and Hospital, Canada. Potentially harmful prenatal events (maternal trauma, medications, roentgenograms, infections) were reported in pregnancy histories of 58% of patients with NMD compared to 15% of 40 epileptic controls without NMD. In contrast, peri- and postnatal factors were present in only 22% of NMD patients compared to 50% of controls. Genetic factors (family history of epilepsy, mental retardation, or CNS malformation) occurred in 13 and 20% of families, respectively. Stillbirths occurred in 3% of NMD sibling pregnancies, but none in controls. Prenatal environmental factors are important in the cause of NMD. 
COMMENT. Maternal physical trauma in the first trimester was the most significant factor associated with NMD. Genetic factors are important in lissencephaly. Dr Harvey B Sarnat comments on advances in neuroblast migratory disorders in Progress in Pediatric Neurology II, PNB Publishers, 1994, pp279-280. Morphological and metabolic abnormalities of the ependyma, and congenital cytomegalovirus were documented as causes, as well as new experimental data on neuroblast migration mediated by radial glial cells.