Patricia A. Carpenter

Plasticity of Language-Related Brain Function During Recovery From Stroke

BACKGROUND AND PURPOSE This study was undertaken to correlate functional recovery from aphasia after acute stroke with the temporal evolution of the anatomic, physiological, and functional changes as measured by MRI. METHODS Blood oxygenation level-dependent contrast and echo-planar MRI were used to map language comprehension in 6 normal adults and in 2 adult patients during recovery from acute stroke presenting with aphasia. Perfusion, diffusion, sodium, and conventional anatomic MRI were used to follow physiological and structural changes. RESULTS The normal activation pattern for language comprehension showed activation predominately in left-sided Wernickes and Brocas areas, with laterality ratios of 0.8 and 0.3, respectively. Recovery of the patient confirmed as having a completed stroke affecting Brocas area occurred rapidly with a shift of activation to the homologous region in the right hemisphere within 3 days, with continued rightward lateralization over 6 months. In the second patient, in whom mapping was performed fortuitously before stroke, recovery of a Wernickes aphasia showed a similar increasing rightward shift in activation recruitment over 9 months after the event. CONCLUSIONS Recovery of aphasia in adults can occur rapidly and is concomitant with an activation pattern that changes from left to a homologous right hemispheric pattern. Such recovery occurs even when the stroke evolves to completion. Such plasticity must be considered when evaluating stroke interventions based on behavioral and neurological measurements.