Introduction: While non-invasive brain and peripheral stimulation have shown promise in treating several neurological impairments, their relevance and potential contributions to dysarthria rehabilitation remain understudied. This research aimed to lay early groundwork for investigating the use of neuromuscular electrical stimulation (NMES) as a therapeutic approach in the treatment of acquired dysarthria.
Methods: A multiple methods approach with five interrelated studies was adopted. Firstly, a systematic review (SR) with meta-analysis (when possible) examined the evidence base of non-invasive stimulation for treating dysarthria and determined safety risks. The second and third studies consisted of two cross-sectional quantitative surveys conducted with speech-language therapists (SLTs) and persons with dysarthria (PwD) respectively and investigated current management approaches for acquired dysarthria, perceived effectiveness and satisfaction levels with treatment, and assessed interest in using NMES for the speech disorder. The fourth study, a qualitative study consisting of semi-structured interviews mapped the development process of NMES devices for neurorehabilitation, the associated barriers and facilitators, and its applicability to acquired dysarthria from the perspective of medical device manufacturers. The fifth study explored the feasibility, tolerability, acceptability and safety, and the potential effectiveness of NMES coupled with traditional dysarthria therapy (TDT) for acquired dysarthria treatment. Lastly, a research protocol for further investigation on the use of surface electromyography (sEMG) in healthy individuals and PwD post-stroke was developed with an aim to investigate the neuromuscular control and execution of several muscle regions during speech execution.
Results: The SR evidenced that despite the fact that non-invasive brain stimulation may provide positive effects, the high risk of bias, heterogeneity of stimulation parameters and outcome measures prevented any conclusions. Peripheral stimulation, specifically NMES, was not investigated using experimental or quasi-experimental methods. SLTs expressed dissatisfaction with current dysarthria rehabilitation and showed interest in NMES, despite limited knowledge. PwDs are generally satisfied with rehabilitation, yet, they expressed interest in NMES, aligning with SLTs' views on NMES. Interviews with NMES manufacturers revealed complexities in device development, with facilitators and barriers identified, as well as indications for the potential applicability of NMES to acquired dysarthria. The two case studies of individuals with chronic post-stroke dysarthria indicate that NMES coupled with TDT is a potentially feasible, acceptable, tolerable, safe and effective treatment approach for dysarthria treatment.
Conclusion: These five studies have established initial groundwork for investigating the use of NMES in acquired dysarthria rehabilitation, demonstrating stakeholder interest and potential applicability. Further research is essential to drive innovation in this research field.
