Evidence-Based Systematic Review: Effects of Neuromuscular Electrical Stimulation on Swallowing and Neural Activation

Abstract

Purpose To systematically review the literature examining the effects of neuromuscular electrical stimulation (NMES) on swallowing and neural activation. The review was conducted as part of a series examining the effects of oral motor exercises (OMEs) on speech, swallowing, and neural activation. Method A systematic search was conducted to identify relevant studies published in peer-reviewed journals from 1960 to 2007. All studies meeting the exclusion/inclusion criteria were appraised for quality and categorized as efficacy or exploratory research based on predetermined criteria. Results Out of 899 citations initially identified for the broad review of OMEs, 14 articles relating to NMES qualified for inclusion. Most of the studies (10/14) were considered exploratory research, and many had significant methodological limitations. Conclusions This systematic review reveals that surface NMES to the neck has been most extensively studied with promising findings, yet high-quality controlled trials are needed to provide evidence of efficacy. Surface NMES to the palate, faucial pillars, and pharynx has been explored in Phase I research, but no evidence of efficacy is currently available. Intramuscular NMES has been investigated in a single Phase I exploratory study. Additional research is needed to document the effects of such protocols on swallowing performance.