Speaking with a single cerebral hemisphere: fMRI language organization after hemispherectomy in childhood.

Speech-related fMRI activation was examined in six hemispherectomy patients (three left LX, three right RX, four with congenital and two with late-acquired hemiplegia) operated in childhood for the relief of drug-resistant epilepsy. Although the temporal and sensorimotor pattern of activation was similar to that found in neurologically intact control participants, activation in Broca's area and its right homolog varied greatly. Involvement of pars triangularis and orbitalis was found in the three cases with best outcome (two RX, one LX), whereas pars opercularis alone was activated in the two remaining LX patients. The results suggest that distinct subregions of Broca's area and their right homologs can subserve speech and language, and that this variability may determine functional outcome.