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Abstract

SummaryBackgroundAphasia affects 1/3 of stroke patients with improvements noted only in some of them. The goal of this exploratory study was to provide preliminary evidence regarding safety and efficacy of fMRI-guided excitatory repetitive transcranial magnetic stimulation (rTMS) applied to the residual left-hemispheric Broca’s area for chronic aphasia treatment.Material/MethodsWe enrolled 8 patients with moderate or severe aphasia >1 year after LMCA stroke. Linguistic battery was administered pre-/post-rTMS; a semantic decision/tone decision (SDTD) fMRI task was used to localize left-hemispheric Broca’s area. RTMS protocol consisted of 10 daily treatments of 200 seconds each using an excitatory stimulation protocol called intermittent theta burst stimulation (iTBS). Coil placement was targeted individually to the left Broca’s.Results6/8 patients showed significant pre-/post-rTMS improvements in semantic fluency (p=0.028); they were able to generate more appropriate words when prompted with a semantic category. Pre-/post-rTMS fMRI maps showed increases in left fronto-temporo-parietal language networks with a significant left-hemispheric shift in the left frontal (p=0.025), left temporo-parietal (p=0.038) regions and global language LI (p=0.018). Patients tended to report subjective improvement on Communicative Activities Log (mini-CAL; p=0.075). None of the subjects reported ill effects of rTMS.ConclusionsFMRI-guided, excitatory rTMS applied to the affected Broca’s area improved language skills in patients with chronic post-stroke aphasia; these improvements correlated with increased language lateralization to the left hemisphere. This rTMS protocol appears to be safe and should be further tested in blinded studies assessing its short- and long-term safety/efficacy for post-stroke aphasia rehabilitation.

Functional Reorganization of Right Prefrontal Cortex Underlies Sustained Naming Improvements in Chronic Aphasia via Repetitive Transcranial Magnetic Stimulation

“…This model assumes that damage to the left hemisphere releases the right hemisphere from transcallosal inhibitory input, resulting in increased right hemisphere activation and, consequently, increased behaviorally deleterious transcallosal inhibition of the already damaged left hemisphere (Fregni and Pascual-Leone, 2007). This model is broadly consistent with evidence of beneficial effects from TMS treatments intended to suppress right IFG activity (Naeser et al, 2005a, 2005b) or excite left perilesional cortical activity (Griffis et al, 2016; Szaflarski et al, 2011). This view reflects studies showing a correlation between better aphasia recovery and the reacquisition of perilesional regions for language processing (Postman-Caucheteux et al, 2010; Rosen et al, 2000; Saur et al, 2006; Szaflarski et al, 2013).…”

“…Previous studies using TMS as an aphasia treatment have applied either inhibitory stimulation to the right prefrontal cortex (Winhuisen et al, 2005, 2007) or excitatory stimulation to the left prefrontal cortex (Griffis et al, 2016; Szaflarski et al, 2011) under the assumption that right hemisphere recruitment is generally maladaptive in aphasia recovery. In particular, this model predicts that suppressing the right IFG, as was done in the current study, should produce language gains by releasing the left hemisphere from the transcallosal inhibitory effects of the overactive right hemisphere, thereby allowing the left hemisphere to reacquire language function (Fregni and Pascual-Leone, 2007).…”

Adaptive Plasticity in the Healthy Language Network: Implications for Language Recovery after Stroke

“…In contrast, the beneficial effect of perilesional facilitation was explored by Szaflarski and colleagues [33] who demonstrated improved semantic fluency in 8 patients with chronic poststroke aphasia after intermittent theta-burst stimulation over the left IFG. The beneficial effect of facilitatory stimulation was underpinned by a leftward shift in language-related activation during subsequent fMRI.…”

“…Notably, some rTMS protocols like intermittent theta-burst stimulation can also facilitate motor cortical excitability [30] and probably also some cognitive processes in the healthy brain, including language [31] and working memory [32]. Such a protocol might thus prove useful to promote language recovery after stroke [33]. …”

Transcranial magnetic stimulation intervention in Alzheimer’s disease: a research proposal for a randomized controlled trial

“…iTBS protocol allows an increase in cortical excitability in a much shorter time than conventional repetitive TMS (3 vs. 30 min) and has been effective, for example, in improving language deficits in Parkinson’s and post-stroke aphasia patients [22, 23]. …”