Objective The primary aim of this review is to evaluate the effects of non-invasive brain stimulation on post-stroke dysphagia. Methods Thirteen databases were systematically searched through July 2014. Studies had to meet pre-specified inclusion and exclusion criteria. Each study's methodological quality was examined. Effect sizes were calculated from extracted data and combined for an overall summary statistic. Results Eight randomized controlled trials were included. These trials revealed a significant, moderate pooled effect size (0.55; 95% CI = 0.17, 0.93; p = 0.004). Studies stimulating the affected hemisphere had a combined effect size of 0.46 (95% CI = −0.18, 1.11; p = 0.16); studies stimulating the unaffected hemisphere had a combined effect size of 0.65 (95% CI = 0.14, 1.16; p = 0.01). At long-term follow up, three studies demonstrated a large but non-significant pooled effect size (0.81, p = 0.11). Conclusions This review found evidence for the efficacy of non-invasive brain stimulation on post-stroke dysphagia. A significant effect size resulted when stimulating the unaffected rather than the affected hemisphere. This finding is in agreement with previous studies implicating the plasticity of cortical neurons in the unaffected hemisphere. Significance Non-invasive brain stimulation appears to assist cortical reorganization in post-stroke dysphagia but emerging factors highlight the need for more data.

Superior and anterior hyoid movements are important events in pharyngeal deglutition. This cross-sectional study uses a cadaver model to document the structural properties of the muscles underlying these movements in an effort to understand how their morphology influences function. Measurements to determine physiological cross-sectional areas (PCSAs) of swallowing muscles were taken from hemisected head and neck formalin-fixed cadaver specimens (n = 13). Coordinates of muscle attachment sites and PCSAs were used to calculate î and ĵ unit force vectors, where î and ĵ represent anterior-posterior and superior-inferior directions, respectively. The suprahyoid muscle subsamples were grouped for analysis as follows: digastric (DG), geniohyoid (GH), mylohyoid (MH), and stylohyoid (SH). The ANOVA with Tukey HSD post hoc analysis of unit force vectors showed the following results: GH (−0.44 ± 0.15 cm2) >MH (−0.02 ± 0.21 cm2), DG (−0.05 ± 0.11 cm2), SH (0.14 ± 0.04 cm2), with negative values representing the anterior direction (p < 0.01); and MH (0.91 ± 0.28 cm2) >DG (0.29 ± 0.14 cm2), SH (0.22 ± 0.08 cm2), GH (12 ± 0.08 cm2), with positive values representing the superior direction (p < 0.01). The morphology of the suprahyoid muscles suggests that based on structural properties, the geniohyoid has the most potential to displace the hyoid in the anterior direction and the mylohyoid has the most potential to displace the hyoid in the superior direction. These data in complement with physiological findings may provide greater insight into these movements for those developing novel treatments for dysphagia.

Post-swallow residue is considered a sign of swallowing impairment. Existing methods for capturing post-swallow residue (perceptual and quantitative) have inherent limitations. We employed several different perceptual and quantitative (ratio) methods for measuring post-swallow residue on the same 40 swallows and addressed the following questions: (1) Do perceptual and quantitative methods demonstrate good agreement? (2) What differences in precision are apparent by measurement method (one-dimensional, two-dimensional, and circumscribed area ratios)? (3) Do residue ratios agree strongly with residue area measures that are anatomically normalized? Based on the findings of this series of questions, a new method for capturing residue is proposed: the Normalized Residue Ratio Scale (NRRS). The NRRS is a continuous measurement that incorporates both the ratio of residue relative to the available pharyngeal space and the residue proportionate to the size of the individual. A demonstration of this method is presented to illustrate the added precision of the NRRS measurement in comparison to other approaches for measuring residue severity.

Summary Elevation of the larynx is critical to swallowing function, an observation supported by the fact that radiation therapy-induced dysphagia is associated with reduced laryngeal elevation. We investigated muscles underlying hyolaryngeal elevation by using muscle functional MRI. We acquired scans from 11 healthy subjects to determine whole-muscle T2 signal profiles pre-swallowing, post-swallowing, and after performing swallowing exercises. Results demonstrate muscles essential to laryngeal elevation and exercises that target them. Purpose Reduced hyolaryngeal elevation, a critical event in swallowing, is associated with radiation therapy. Two muscle groups that suspend the hyoid, larynx, and pharynx have been proposed to elevate the hyolaryngeal complex: the suprahyoid and longitudinal pharyngeal muscles. Thought to assist both groups is the thyrohyoid, a muscle intrinsic to the hyolaryngeal complex. Intensity modulated radiation therapy guidelines designed to preserve structures important to swallowing currently exclude the suprahyoid and thyrohyoid muscles. This study used muscle functional magnetic resonance imaging (mfMRI) in normal healthy adults to determine whether both muscle groups are active in swallowing and to test therapeutic exercises thought to be specific to hyolaryngeal elevation. Methods and Materials mfMRI data were acquired from 11 healthy subjects before and after normal swallowing and after swallowing exercise regimens (the Mendelsohn maneuver and effortful pitch glide). Whole-muscle transverse relaxation time (T2 signal, measured in milliseconds) profiles of 7 test muscles were used to evaluate the physiologic response of each muscle to each condition. Changes in effect size (using the Cohen d measure) of whole-muscle T2 profiles were used to determine which muscles underlie swallowing and swallowing exercises. Results Post-swallowing effect size changes (where a d value of >0.20 indicates significant activity during swallowing) for the T2 signal profile of the thyrohyoid was a d value of 0.09; a d value of 0.40 for the mylohyoid, 0.80 for the geniohyoid, 0.04 for the anterior digastric, and 0.25 for the posterior digastric-stylohyoid in the suprahyoid muscle group; and d values of 0.47 for the palatopharyngeus and 0.28 for the stylopharyngeus muscles in the longitudinal pharyngeal muscle group. The Mendelsohn maneuver and effortful pitch glide swallowing exercises showed significant effect size changes for all muscles tested, except for the thyrohyoid. Conclusions Muscles of both the suprahyoid and the longitudinal pharyngeal muscle groups are active in swallowing, and both swallowing exercises effectively target muscles elevating the hyolaryngeal complex. mfMRI is useful in testing swallowing muscle function.