Essential language function of the right hemisphere in brain tumor patients.

Neuroimaging studies of language networks in patients with brain lesions of the left language-dominant hemisphere have shown activation in the right inferior frontal gyrus (IFG). We tested the functional relevance of right IFG activation using neuroimaging-guided repetitive transcranial magnetic stimulation (rTMS) to disturb language function over bilateral IFG in right-handed patients with brain tumors and controls. All subjects were susceptible to TMS over the left IFG. In patients, this susceptibility correlated with left-sided the degree of language lateralization to the left. Those patients with lowest dominance were also susceptible to right-sided TMS proving relevant language function of the right IFG.