New Treatment Strategy Using Repetitive Transcranial Magnetic Stimulation for Post-Stroke Aphasia

Repetitive transcranial magnetic stimulation (rTMS) for post-stroke aphasia (PSA) has been suggested to promote improvement of language function when used in combination with rehabilitation. However, many challenges remain. In some reports examined by category of language function, only naming has good evidence of improvement, and the improvement effect on other language modalities is low. Therefore, it is necessary to establish methods that contribute to the improvement of language functions other than naming. Therapeutic methods for PSA based on the mechanism of rTMS are mainly inhibitory stimulation methods for language homologous areas. However, the mechanisms of these methods are controversial when inferred from the process of recovery of language function. Low-frequency rTMS applied to the right hemisphere has been shown to be effective in the chronic phase of PSA, but recent studies of the recovery process of language function indicate that this method is unclear. Therefore, it has been suggested that evaluating brain activity using neuroimaging contributes to confirming the effect of rTMS on PSA and the elucidation of the mechanism of functional improvement. In addition, neuroimaging-based stimulation methods (imaging-based rTMS) may lead to further improvements in language function. Few studies have examined neuroimaging and imaging-based rTMS in PSA, and further research is required. In addition, the stimulation site and stimulation parameters of rTMS are likely to depend on the time from onset to intervention. However, there are no reports of studies in patients between 90 and 180 days after onset. Therefore, research during this period is required. New stimulation methods, such as multiple target methods and the latest neuroimaging methods, may contribute to the establishment of new knowledge and new treatment methods in this field.