Exploring stimulation patterns for electrical stimulation of the larynx using surface electrodes
Functional electrical stimulation (FES) is considered an upcoming treatment modality for a number of laryngeal diseases. However, sound data are scarce when it comes to surface FES to treat voice disorders. Aim of the present study was to identify and differentiate suitable surface FES patterns to activate internal laryngeal muscles.
Non-invasive FES was performed in a cohort of 17 elderly woman. Our user-customized electrical stimulation setup allowed us to deliver ten different stimulation patterns (rectangular and sawtooth shaped) with variation of frequency and amplitude. Stimulation outcome, i.e., vocal fold (VF) reaction, was continuously verified by transnasal endoscopy.
Responses to FES using ten different stimulation patterns varied inter-individually. None of the stimulation parameter sets could elicit a VF reaction in all participants.
Based on our findings we conclude that individual fitting is necessary when defining surface stimulation parameters. To overcome limitations of previous studies, devices with freely programmable patterns are required as shown here. Endoscopic control of VF reaction is absolutely essential to ensure effectiveness of the delivered patterns.
KeywordsLaryngeal functional electrical stimulation Transcutaneous electrical stimulation Voice rehabilitation Presbyphonia Dysphonia
This work was supported by the Austrian Research Promotion Agency (Österreichische Forschungsförderungsgesellschaft), fund no. 848458.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in this study were in accordance with the ethical standards of the ethics committee of the Medical University of Graz and with the 1964 Helsinki Declaration and its later amendments.
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