Fields or flows? A comparative metaanalysis of transcranial magnetic and direct current stimulation to treat post-stroke aphasia

Shah-Basak, Priyanka P.; Wurzman, Rachel; Purcell, Juliann B.; Gervits, Felix; Hamilton, Roy H.

doi:10.3233/rnn-150616

Cited by 39 publications

(55 citation statements)

References 74 publications

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“…Importantly, future studies should also employ sample sizes that are sufficient to provide greater statistical power. However, we would also note that we have, in previously published work, been able to demonstrate a significant effect of non-invasive brain stimulation on language ability in cohorts of persons with aphasia with similarly small sample sizes - 6 and 10 (Medina et al, 2012; Shah-Basak et al, 2016). In these studies, we were able to demonstrate an effect on overall aphasia severity following tDCS (Shah-Basak et al, 2016) and an effect on fluency following TMS (Medina et al, 2012).…”

Section: Discussionmentioning

confidence: 54%

Transcranial Direct Current Stimulation in Post-stroke Chronic Aphasia: The Impact of Baseline Severity and Task Specificity in a Pilot Sample

Norise

Sacchetti

Hamilton

2017

Front. Hum. Neurosci.

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Emerging evidence suggests that transcranial direct current stimulation (tDCS) can improve aspects of language production in persons with chronic non-fluent aphasia due to left hemisphere stroke. However, to date, studies exploring factors that predict response to tDCS in this or any patient population remain sparse, as are studies that investigate the specific aspects of language performance that are most responsive to stimulation. The current study explored factors that could predict recovery of language fluency and which aspects of language fluency could be expected to improve with the identified factor(s). We report nine patients who demonstrated deficits in fluency as assessed using the Cookie Theft picture description task of the Boston Diagnostic Aphasia Examination. In the treatment condition, subjects received a 2.0 mA current through 5 cm × 5 cm electrodes for 20 min at a site previously shown to elicit a patient-dependent optimal response to tDCS. They were then tested 2-weeks and 2-months after treatment. In the sham condition, a subset of these subjects were tested on the same protocol with sham instead of real tDCS. The current study assessed language fluency improvements in measures of production at the word-level and sentence level, grammatical accuracy, and lexical selection as a function of baseline aphasia severity. A more severe baseline language profile was associated with larger improvements in fluency at the word-level after real tDCS but not sham stimulation. These improvements were maintained at the 2-week follow-up. The results suggest that for at least some outcome measures, baseline severity may be an important factor in predicting the response to tDCS in patients with chronic non-fluent aphasia. Moving forward, the ability to identify patient factors that can predict response could help refine strategies for the administration of therapeutic tDCS, focusing attention on those patients most likely to benefit from stimulation.

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Section: Discussionmentioning

confidence: 54%

Transcranial Direct Current Stimulation in Post-stroke Chronic Aphasia: The Impact of Baseline Severity and Task Specificity in a Pilot Sample

Norise

Sacchetti

Hamilton

2017

Front. Hum. Neurosci.

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“…However, to date no investigation has directly investigated the efficacy of different sides of stimulation at different phases of post-stroke recovery. A recent meta-analysis by Shah-Basak et al (2016) investigated the efficacy of rTMS and tDCS, including a subanalysis that explored stimulation at different post-stroke phases. They found comparable effect sizes in subacute and chronic studies, though the majority of studies employed a similar approach: low frequency stimulation of the right hemisphere.…”

Section: Tms and Tdcs In The Treatment Of Post-stroke Aphasiamentioning

confidence: 99%

“…Shah-Basak et al (2016) examined the relevance of stroke chronicity in a meta-analysis, demonstrating that tDCS delivered in the subacute period resulted in a smaller and less consistent language benefit than stimulation applied in the chronic phase. However, it is unclear from this analysis whether the difference in effect was related to consistent differences in study design between subacute (all between-subject) and chronic (within-subject) investigations.…”

Section: Tms and Tdcs In The Treatment Of Post-stroke Aphasiamentioning

confidence: 99%

Non-invasive Brain Stimulation in the Treatment of Post-stroke and Neurodegenerative Aphasia: Parallels, Differences, and Lessons Learned

Norise

Hamilton

2017

Front. Hum. Neurosci.

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Numerous studies over the span of more than a decade have shown that non-invasive brain stimulation (NIBS) techniques, namely transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can facilitate language recovery for patients who have suffered from aphasia due to stroke. While stroke is the most common etiology of aphasia, neurodegenerative causes of language impairment—collectively termed primary progressive aphasia (PPA)—are increasingly being recognized as important clinical phenotypes in dementia. Very limited data now suggest that (NIBS) may have some benefit in treating PPAs. However, before applying the same approaches to patients with PPA as have previously been pursued in patients with post-stroke aphasia, it will be important for investigators to consider key similarities and differences between these aphasia etiologies that is likely to inform successful approaches to stimulation. While both post-stroke aphasia and the PPAs have clear overlaps in their clinical phenomenology, the mechanisms of injury and theorized neuroplastic changes associated with the two etiologies are notably different. Importantly, theories of plasticity in post-stroke aphasia are largely predicated on the notion that regions of the brain that had previously been uninvolved in language processing may take on new compensatory roles. PPAs, however, are characterized by slow distributed degeneration of cellular units within the language system; compensatory recruitment of brain regions to subserve language is not currently understood to be an important aspect of the condition. This review will survey differences in the mechanisms of language representation between the two etiologies of aphasia and evaluate properties that may define and limit the success of different neuromodulation approaches for these two disorders.

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“…One recent meta-analysis found statistically significant improvements in people with aphasia using tDCS 71 , while another meta-analysis reported some promise using cathodal stimulation over the contralateral hemisphere, but found no statistical significance regarding the effects of tDCS for aphasia overall 56 .…”

Section: Tdcs/aphasia Literature Reviewsmentioning

confidence: 99%

Transcranial Direct Current Stimulation in Poststroke Aphasia Recovery

Wortman-Jutt

Edwards

2017

Stroke

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Fields or flows? A comparative metaanalysis of transcranial magnetic and direct current stimulation to treat post-stroke aphasia

Abstract: The magnitude of treatment effects appears to be consistent between TMS and tDCS in PWA. Larger-scale clinical trials should further substantiate our findings.

Cited by 39 publications

References 74 publications

Transcranial Direct Current Stimulation in Post-stroke Chronic Aphasia: The Impact of Baseline Severity and Task Specificity in a Pilot Sample

Transcranial Direct Current Stimulation in Post-stroke Chronic Aphasia: The Impact of Baseline Severity and Task Specificity in a Pilot Sample

Non-invasive Brain Stimulation in the Treatment of Post-stroke and Neurodegenerative Aphasia: Parallels, Differences, and Lessons Learned

Transcranial Direct Current Stimulation in Poststroke Aphasia Recovery

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