The persistent and broadly modulating effect of inhibitory rTMS in nonfluent aphasic patients: a sham-controlled, double-blind study

Abstract

Background: While prior preliminary studies have broadened our understanding of how repetitive transcranial magnetic stimulation (rTMS) improves language outcomes in stroke patients with nonfluent aphasia, the evidence base of the effectiveness of this method remains inadequate.

Objective: In this study, we aimed to strengthen the evidence that this approach improves language performance and to identify characteristics of patients predisposed to benefit most from this treatment.

Methods: Fifty-six stroke patients with nonfluent aphasia were randomly allocated to a real or a sham stimulation group: Group A (n = 33), who underwent 10 sessions of 1-Hz rTMS over the contralesional pars triangularis (PTr), and Group B (n = 23), who received sham 1-Hz stimulation. We performed the Picture Naming Test and the Concise Chinese Aphasia Test (CCAT) at the baseline, post-rTMS intervention, and at 3-month follow-up.

Results: Group A showed significantly greater improvement than Group B in CCAT scoring (P < .001), object-naming accuracy (P = .01), and naming reaction time (P = .004). The CCAT scoring and naming testing changes for Group A were persistent at 3 months following intervention (P = .008). Patients who had a lower contralesional rest motor threshold (rMT) were predisposed to a favorable therapeutic outcome (P = .006), independent of aphasia type, severity, and duration.

Conclusions: The results of this study provide evidence that inhibitory rTMS, through downregulating the circuitry of the right pars triangularis (PTr), achieves a persistent and broadly modulating effect, irrespective of aphasia severity and subtype. Patients who show lower rMT in the right motor system would seem to benefit the most from inhibitory rTMS.

Keywords: aphasia; neuroplasticity; nonfluent aphasia; pars triangularis; repetitive transcranial magnetic stimulation; stroke.