Magnetic resonance imaging and neurobehavioral correlates in schizencephaly

The germinal matrix is the birthplace of neurons during embryonic development. If the neuroblasts (nerve cell precursors) born here fail to migrate normally to their proper location, all of the succeeding events of brain development are altered as well. Such an abnormal sequence of developmental events is thought to be responsible for schizencephaly, in which pathological clefts in the brain are among the abnormal findings. Schizencephalies, the term for these malformations, are always the result of abnormal development, and must be distinguished from other conditions in which developing brain tissue is destroyed. The authors review three cases of schizencephaly and contrast the neuropsychological deficits with the appearance of the brain on magnetic resonance imaging. Two of the patients were examined for seizure activity; the third was seen because of muscle weakness. Two of the three patients showed slow development as children, but all had graduated high school and lead normal lives. The magnetic resonance images revealed striking abnormalities of the lobes of the brain, including large clefts. A curious finding was that all three patients were left-handed. The patients did not have any difficulty with normal conversational language, but comprehensive assessment revealed some deficits in language skills. The results of this study are an example of how developmental brain damage which does not show up as global mental retardation or a decrease in IQ scores can nevertheless be identified on occasion by comprehensive neuropsychologic testing. (Consumer Summary produced by Reliance Medical Information, Inc.)