Language recovery after left hemispherectomy in children with late-onset seizures.

We investigated the language capabilities of the isolated right hemisphere in 6 children (age, 7-14 years) after left hemidecorticectomy for treatment of Rasmussen's syndrome. Patients were right-handed before surgery and had at least 5 years of normal language development before the onset of seizures. Language testing included speech sound (phoneme) discrimination, single word and phrasal comprehension, repetition, and naming. Within 4 to 16 days after surgery, patients showed improved phoneme discrimination compared with their performance shortly before surgery. Other language functions remained severely impaired until at least 6 months after surgery. By 1 year after surgery, receptive functions were comparable with, or surpassed, patient presurgery performance. Although word repetition was intact by 1 year after surgery, naming remained impaired, and patient speech was limited largely to production of single words. These results suggest that the right hemisphere is innately capable of supporting multiple aspects of phoneme processing. Recovery of higher level receptive and, to a lesser extent, expressive language functions is attributed to plasticity of the right hemisphere, which appears to persist beyond the proposed critical period for language acquisition and lateralization.