[Neuroimaging and neurorehabilitation for aphasia]

With the development of neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), many reports revealing the underlying mechanisms of functional recovery from aphasia have been published. Three types of compensatory mechanisms seem to operate in aphasic patients with left hemisphere damage: (1) functional recovery of the damaged area in the left hemisphere, (2) activation of the perilesional area in the left hemisphere, and (3) activation of the right frontal area (area homologous to the language-relevant area). Although there are some pitfalls in the interpretation of neuroimaging, it is recommended that the areas that compensate for impaired language function should be clarified prior to the initiation of neurorehabilitation for aphasia. The clinical effectiveness of repetitive transcranial magnetic stimulation (rTMS) and pharmacotherapy for aphasia has been recently studied. We administered low-frequency rTMS and language therapy to 4 stroke patients with motor-dominant aphasia for 6 consecutive days. The application site of rTMS was determined on the basis of the findings of pretreatment fMRI during word repetition tasks. Our novel approach resulted in significant improvement in language functions. The results of some double-blind placebo-controlled trials on aphasic patients have indicated that levodopa, dextroamphetamine, and donepezil play a critical role in the recovery from aphasia. We anticipate limitless future possibilities for the intensive neurorehabilitation of aphasic patients, including constraint-induced language therapy, rTMS application, and pharmacotherapy. The application of newly developed neuroimaging techniques may provide additional important information for improving neurorehabilitative intervention for aphasia.