HYPOPLASIA OF THE CORPUS-CALLOSUM - A STUDY OF 445 CONSECUTIVE MRI SCANS

The size of the corpus callosum was assessed visually and by computer- assisted image analysis in a series of 445 consecutive magnetic resona nce imaging (MRI) scans in children under 17 years of age. Fifty indiv iduals were subjectively identified with small corpora callosa on visu al inspection of the MRI scans. Seven patients had true hypoplasia of the corpus callosum after comparing the computer-measured relative siz e of the structure to previously established normal values. Five addit ional patients had complete agenesis, and two had partial agenesis of the corpus callosum. The cognitive functional levels of the seven pati ents with callosal hypoplasia and a control group of 63 randomly selec ted individuals from the remainder of the group were ascertained by re cord review. Seventy-one percent of the patients with hypoplasia of th e corpus callosum and 29% of the control group had impaired function. The P value determined by Fisher's exact test was P =.061, suggesting that further study with greater numbers may be warranted. The prevalen ce of mental retardation in this condition, and the fact that hypoplas ia is as common as complete and partial agenesis of the corpus callosu m combined, suggest that hypoplasia of the corpus callosum is a marker of cerebral dysgenesis that should be looked for in the appropriate c linical setting.