RECOVERY FROM WERNICKES APHASIA - A POSITRON EMISSION TOMOGRAPHIC STUDY

Changes in the organization of the brain after recovery from aphasia w ere investigated by measuring increases in regional cerebral blood flo w (rCBF) during repetition of pseudowords and during verb generation. Six right-handed patients who had recovered from Wernicke's aphasia ca used by an infarction destroying the left posterior perisylvian langua ge zone were compared with 6 healthy, right-handed volunteers. In the control subjects, strong rCBF increases were found in the left hemisph ere in the posterior part of the superior and middle temporal gyrus (W ernicke's area), and during the generation task in lateral prefrontal cortex (LPFC) and in inferior frontal gyrus (Broca's area). There were some weak right hemisphere increases in superior temporal gyrus and i nferior premotor cortex. In the patients, rCBF increases were preserve d in the frontal areas. There was clear right hemisphere activation in superior temporal gyrus and inferior premotor and lateral prefrontal cortices, homotopic to the left hemisphere language zones. Increased l eft frontal and right perisylvian activity in patients with persisting destruction of Wernicke's area emphasizes redistribution of activity within the framework of a preexisting, parallel processing and bilater al network as the central mechanism in functional reorganization of th e language system after stroke.