Postcallosotomy language impairments in patients with crossed cerebral dominance.

Language impairments were reviewed retrospectively in patients who underwent partial or total corpus callosum section for medically refractory secondary generalized epilepsy. Postoperatively, four of 32 patients had clinically significant language impairments that were not present prior to the operation. All involved primarily verbal output (speech and writing) and spared verbal comprehension. Written language skills (reading and spelling), verbal memory, and verbal reasoning abilities were impaired to varying degrees. These impairments were associated with crossed cerebral dominance. Three patients with severe difficulties after surgery were right hemisphere-dominant for speech and were right-handed. One left hemisphere speech-dominant, left-handed patient was agraphic after surgery, but spoke normally. It is concluded from these data and from other reports in the literature that three syndromes of language disturbance may follow callosotomy. The first, involving speech difficulty but but sparing writing, is attributable to buccofacial apraxia. The second involves speech and writing difficulties and occurs in right hemisphere-dominant right-handed patients. The third involves dysgraphia with intact speech and occurs in left hemisphere-dominant left-handed patients.