Effects of single-session repetitive transcranial magnetic stimulation to identify the optimal brain target in primary progressive aphasia

Abstract

Background: Non-invasive brain stimulation has shown positive results in maximizing the effects of language therapy in primary progressive aphasia (PPA). Due to the different patterns of brain damage in each aphasia variant, we hypothesized that patients with non-fluent and semantic variants would show a differential response to transcranial magnetic stimulation (TMS). Objective: We aimed to compare the clinical responses after a single session of repetitive TMS in the left inferior frontal gyrus (IFG) and the left dorsolateral prefrontal cortex (DLPC). Methodology: Twenty patients with PPA (14 with non-fluent and 6 with semantic variants) were assessed before and after repetitive TMS over the IFG, DLPC, and vertex with several language tasks, connected speech, and a subjective impression of change scale. Results: IFG stimulation was associated with an improvement in words per minute and the subjective assessment in the non-fluent variant, but no effects were found in the semantic variant. DLPC stimulation was associated with an improvement in words per minute, repetition, and naming latency in the non-fluent variant, and in naming and subjective impression of change in the semantic variant. Conclusions: Our study showed a differential effect of one session of brain stimulation over the IFG and DLPC in patients with non-fluent and semantic PPA variants. These findings suggest that the selection of the target of stimulation may be relevant for the success of brain stimulation and favor the use of DLPC over the IFG.