Midsagittal corpus callosum area, intelligence, and language dominance in epilepsy

Alterations in midsagittal corpus callosum (CC) area and morphology have been suggested in several disease processes of the nervous system. In addition, some studies found a relation of CC area to handedness, language dominance, and gender. The relation of CC area to measures of intelligence and memory and the effect of epilepsy on CC area have received less attention. In this study CC area was measured on midsagittal magnetic resonance images in 48 patients undergoing presurgical evaluation of epilepsy and in 20 control subjects. All patients had the Wada test and formal neuropsychological testing. The mean CC area of the epilepsy group was significantly smaller than that of control subjects (p < 0.00001). CC area showed a positive correlation with presurgical performance IQ (p = 0.008) and full-scale IQ (p = 0.048), but not with memory scores or language dominance. There was no relation of CC area to location of epileptic focus, seizure types, age at onset, epilepsy duration, or etiology. The presence of an atrophic lesion was associated with a smaller CC area. The correlation of total CC area with performance and full-scale IQs may reflect axonal loss in patients with a low IQ, resulting from the etiology of epilepsy or the epilepsy itself.