Mouth asymmetry during speech of epileptic patients who have undergone carotid amytal testing.

Asymmetry in the opening of the two sides of the mouth during speech has been suggested as an observable correlate of lateralization of cerebral speech motor control. For 24 epileptic patients who suffered speech disturbance only during left hemisphere carotid amytal anesthetization, 22 showed the expected greater opening of the right side of the mouth during a repetition task. However, all four of the patients who suffered speech disturbance following only right hemisphere anesthetization, and 8 of the 11 "bilateral speech" patients, also showed greater opening of the right side of the mouth. The speech dominant patients may, however, have genetic left speech dominance but a pathology-forced shift of some components of language to the right hemisphere. Basic mouth asymmetry, as measured here, may primarily reflect lateralization of a component of the motor/speech/language control system that may not be shifted by pathology in epileptic patients sustaining early brain insult. Relative change in mouth asymmetry as the speech task becomes more demanding may, however, be a more sensitive indicator or cerebral asymmetries for language in pathological cases.