HEMIMEGALENCEPHALY - LOCALIZED PROTON MAGNETIC-RESONANCE SPECTROSCOPYIN-VIVO

Two children with hemimegalencephaly were examined by magnetic resonan ce imaging (MRI) and localized proton MR spectroscopy (MRS), In both c ases, structural changes in the enlarged hemisphere included pachy- or polymicrogyria and gliosis of white matter. Associated metabolic dist urbances included a dramatic reduction of glutamate and N-acetylaspart ate (NAA) in white matter. Less severe or no alterations were noted in cortical gray matter, basal ganglia, and cerebellum. The older child (13 years) showed increased myoinositol in both gray and white matter as well as markedly increased choline-containing compounds in gray mat ter. Both children also had mildly decreased NAA levels in the white m atter of the contralateral hemisphere. The spectroscopic findings indi cate loss of vital neuroaxonal tissue and glial cell proliferation. Me tabolic disturbances were more pronounced in the older child. The norm al-appearing hemisphere was mildly affected in both cases.