Episodic aphemia and epileptic focus in nondominant hemisphere: relieved by section of corpus callosum.

A patient had right hemiparesis since infancy. At age 31, she had recurrent right focal motor and sensory seizures. In prolonged focal seizures, she could not speak but retained most other language-related functions. Intracarotid cerebral amytal testing demonstrated right hemisphere speech. Left intracarotid amytal injection stopped a typical attack. Complete section of the corpus callosum abolished the aphemic episodes and reduced the frequency and intensity of the focal seizures. Focal seizure activity in the left nondominant hemisphere appears to have caused restricted functional disturbance in the right dominant hemisphere.