Language representation in a patient with a dominant right hemisphere: fMRI evidence for an intrahemispheric reorganisation

Studies have suggested that congenital left hemispheric (LH) frontal arteri ovenous malformations (AVMs) are associated with an early transfer of langu age to right hemisphere (RH) frontal regions. The question remains whether such anatomo-functional reorganisation is due to RH compensatory abilities or to a general principle of lateral shift. In this study, we used fMRI lan guage paradigms to investigate the case of a patient presenting aphasic sym ptoms following an haemorrhage due to a right frontal AVM. Prior to surgery , fMRI showed that language processing was confined to the RH, suggesting t hat language had not shifted during childhood from this congenitally domina nt RH to the LH. After surgery, the patient presented severe aphasia that r ecovered to presurgical level within 70 days. At this time, fMRI showed tha t language tasks were still not associated with activations in the LH. Thes e results suggest that the principles of early cerebral reorganisation afte r congenital lesions may differ in the RH and the LH. In addition, they sup port the idea that efficient restoration of language is achieved if a suffi ciently large neuronal network is preserved around the lesion. NeuroReport 12:2785-2790 (C) 2001 Lippincott Williams & Wilkins.