Combining Cerebellar tDCS and Constraint-induced Language Therapy in Non-fluent Aphasia: a Novel Approach to Target Discourse

Detailed Summary

The long-term goal of this work is to determine if combining a highly intensive, task-specific behavioral language intervention with modulation of the efferent cerebellar-cortical pathway using transcranial direct current stimulation (tDCS) has a positive influence on discourse, verbal fluency and working memory in individuals with non-fluent aphasia after stroke. And if these changes can be related to neuroplastic change in the cerebellar cortical pathway indirectly measured through neurophysiologic changes using spectral electroencephalogram (EEG). The initial phase includes the proposed pilot study data from which will be used to inform a larger clinical trial. The primary aims of this pilot are to 1) determine the effect of combining cerebellar tDCS with constraint-induced language therapy (CILT) on language as measured by a verbal fluency task and discourse task in a small population and 2) identify the tolerance of the intervention and barriers to participation measured by the adverse events questionnaire that will inform the methodology of a larger study. The secondary aims include estimating the size of the treatment effect on 1) delta percentage in F3, F7 and Fp1 compared to F4, F8, and Fp2 using resting state EEG spectral analysis and coherence, 2) working memory as measured by the score on the n-back test and 3) quality of life as measured by the Stroke Aphasia Quality of Life survey tool. The secondary aims will be used to determine the utility of these measures in a larger clinical trial. This is a prospective, crossover study, sham-controlled intervention study with two intervention conditions delivered across 6 intervention sessions (3x/week for two weeks) with a 4-week washout in between. Conditions include: 1) sham cerebellar tDCS and 2) real cerebellar tDCS delivered at 2mA across 20 minutes. Each of these will be delivered during CILT intervention with a licensed, certified speech-language pathologist trained in CILT. Once tDCS stimulation has ended, CILT will continue to be delivered for an additional 25 minutes. Assessments of discourse, verbal fluency, working memory and EEG spectral analysis will be conducted at four timepoints, before and after each intervention phase.

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