Abstract
Transcranial direct-current stimulation (tDCS) has been suggested to improve language function in patients with post-stroke aphasia. Most studies on aphasic patients, however, were conducted with a very limited follow-up period, if any. In this pilot, single-blind study on chronic post-stroke aphasic patients, we aimed to verify whether or not tDCS is able to extend its beneficial effects for a longer period of time (21 weeks after the end of stimulation). Three aphasic patients underwent anodal tDCS (A-tDCS, 20 min, 1.5 mA) and sham stimulation (S-tDCS) over the left frontal (perilesional) region, coupled with a simultaneous naming training (on-line tDCS). Ten consecutive sessions (5 days per week for 2 weeks) were implemented. In the first five sessions, we used a list of 40 figures, while in the subsequent five sessions we utilized a second set of 40 figures differing in word difficulty. At the end of the stimulation period, we found a significant beneficial effect of A-tDCS (as compared to baseline and S-tDCS) in all our subjects, regardless of word difficulty, although with some inter-individual differences. In the follow-up period, the percentage of correct responses persisted significantly better until the 16th week, when an initial decline in naming performance was observed. Up to the 21st week, the number of correct responses, though no longer significant, was still above the baseline level. These results in a small group of aphasic patients suggest a long-term beneficial effect of on-line A-tDCS.
Highlights
Non-invasive brain stimulation (NIBS) techniques have recently emerged in restorative neurology due to their hypothetical advantage in enhancing the efficacy of traditional therapeutic intervention (Holland and Crinion, 2012)
These works converged in a body of evidence that A-transcranial direct-current stimulation (tDCS) can improve language performances when applied to the left hemisphere (LH), on the frontal cortex (Monti et al, 2013), whose residual activity is supposed to allow speech production (Fridriksson et al, 2010)
We found a clear beneficial effect of A-tDCS in all our subjects
Summary
Non-invasive brain stimulation (NIBS) techniques have recently emerged in restorative neurology due to their hypothetical advantage in enhancing the efficacy of traditional therapeutic intervention (Holland and Crinion, 2012) In this view, the re-discovery of the application of a direct-current flow of low intensity (1–2 μA) has raised much interest. Recent evidence suggests that tDCS is a safe and (relatively) painless instrument for manipulating performance in a variety of motor and cognitive domains, and investigators have started exploring the use of tDCS as a possible rehabilitative tool for patients with post-stroke deficits, including impairment of language. These works converged in a body of evidence that A-tDCS can improve language performances when applied to the left hemisphere (LH), on the frontal cortex (Monti et al, 2013), whose residual activity is supposed to allow speech production (Fridriksson et al, 2010)
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