The effect of bi-hemispheric transcranial direct current stimulation on verbal function in Broca's aphasia

Abstract

Aphasia is one of the most common deficits occurring after stroke that remains, at least in part, even after speech therapy and medication treatment. Non-invasive direct current transcranial stimulation (tDCS) is used to improve brain function by induction of neural plasticity. This study investigated the effect of bi-hemispheric tDCS on verbal function in patients with stroke-induced Broca's aphasia. Thirty patients with Broca's aphasia due to ischemic stroke, referred to an academic hospital in Guilan Province, Iran, in 2019-20, were studied. Patients were divided into two groups receiving seven sessions of either active or sham tDCS. The tDCS sessions began 10–20 days after stroke onset. The severity of aphasia before and after the intervention and a 3-month follow-up were assessed by the Persian version of the Western Battery-1 test (P-WAB-1). T-test, ANOVA, and Repeated Measurement were used for data analyses. The mean P-WAB-1 score was significantly higher in the intervention group both early after tDCS (P ≤ 0.0001) and on the 3-months follow-up (P ≤ 0001). Linear regression analysis indicated that tDCS had a positive effect on verbal performance scores independent of age, sex, and lesion volume (Regression coefficient = −33.3). Bi-hemispheric tDCS effectively improves verbal function in Broca's aphasia in the sub-acute phase of ischemic stroke.