Atypical hemispheric language dominance in left temporal lobe epilepsy as a result of the reorganization of language functions.

Hemispheric language dominance, as determined by intracarotid short-acting barbiturate injections (Wada testing), was retrospectively evaluated in 44 right-handed patients with medically intractable left (n=26) or right (n=18) temporal lobe epilepsy (TLE). Atypical hemispheric language dominance (right or bilateral) was revealed in 13.6% of all patients investigated. A significantly higher rate of deviance from complete left hemisphere dominance was observed in left TLE (23.1%) than in right TLE (0%). Patient age at the time of seizure onset was proven a critical variable affecting atypical speech development in left TLE. The mean patient age at the time of seizure onset in left TLE patients with atypical language representation was 5.61 years, but was 13.13 years in patients with left hemisphere language dominance. Our results strongly support the influential impact of epileptiform activity spreading from the left temporal lobe structures on the reorganization of language functions in patients with early brain injury.