A literature review was conducted on hyoid and/or laryngeal displacement during swallowing in healthy populations according to several inclusion criteria. Anterior and superior displacement measures of both structures from previously published studies were compiled for meta-analysis. Results showed a large degree of variability across studies for each structure and plane of movement. Potential sources of variation were identified, including statistical, methodological, stimulus-related, and participant-related sources.

Physiological Variability in the Deglutition Literature: Hyoid and Laryngeal Kinematics

Background

Chronic poststroke oropharyngeal dysfunction (OD) is a common condition, leading to severe complications, including death. Treatments for chronic poststroke OD are scarce. The aim of our study was to assess and compare the efficacy and safety of treatment with surface electrical stimulation (e-stim) at sensory and motor intensities in patients with chronic poststroke OD.



Methods

Twenty chronic poststroke patients with OD were randomly assigned to (i) sensory e-stim (treatment intensity: 75% of motor threshold) or (ii) motor e-stim (treatment intensity: motor threshold). Patients were treated during 10 days, 1 h/day. Videofluoroscopy was performed at the beginning and end of the study to assess signs of impaired efficacy and safety of swallow and timing of swallow response.



Key Results

Patients presented advanced age (74.95 ± 2.18), 75% were men. The mean days poststroke was 336.26 ± 89.6. After sensory stimulation, the number of unsafe swallows was reduced by 66.7% (p < 0.001), the laryngeal vestibule closure time by 22.94% (p = 0.027) and maximal vertical hyoid extension time by 18.6% (p = 0.036). After motor stimulation, the number of unsafe swallows was reduced by 62.5% (p = 0.002), the laryngeal vestibule closure time by 38.26% (p = 0.009) and maximal vertical hyoid extension time by 24.8% (p = 0.008). Moreover, the motor stimulus reduced the pharyngeal residue by 66.7% (p = 0.002), the upper esophageal sphincter opening time by 39.39% (p = 0.009), and increased bolus propulsion force by 211.1% (p = 0.008). No serious adverse events were detected during the treatment.



Conclusions & Inferences

Surface e-stim is a safe and effective treatment for chronic poststroke dysphagic patients.

Effect of surface sensory and motor electrical stimulation on chronic poststroke oropharyngeal dysfunction

Objective:To evaluate the effectiveness of inspiratory/expiratory muscle training (IEMT) and neuromuscular electrical stimulation (NMES) to improve dysphagia in stroke.Design:Prospective, single-blind, randomized-controlled trial.Setting:Tertiary public hospital.Subjects:Sixty-two patients with dysphagia were randomly assigned to standard swallow therapy (SST) (Group I, controls, n=21), SST+ IEMT (Group II, n=21) or SST+ sham IEMT+ NMES (Group III, n=20).Interventions:All patients followed a 3-week standard multidisciplinary rehabilitation program of SST and speech therapy. The SST+IEMT group’s muscle training consisted of 5 sets/10 repetitions, twice-daily, 5 days/week. Group III’s sham IEMT required no effort; NMES consisted of 40-minute sessions, 5 days/week, at 80Hz.Main outcomes:Dysphagia severity, assessed by Penetration-Aspiration Scale, and respiratory muscle strength (maximal inspiratory and expiratory pressures) at the end of intervention and 3-month follow-up.Results:Maximal respiratory pressur...

Respiratory muscle strength training and neuromuscular electrical stimulation in subacute dysphagic stroke patients: A randomized controlled trial

Normal contractile algorithm of swallowing related muscles revealed by needle EMG and its comparison to videofluoroscopic swallowing study and high resolution manometry studies: A preliminary study

OBJECTIVE To investigate the therapeutic effects of repetitive electrical stimulation of the suprahyoid muscles in brain-injured patients with dysphagia. METHOD Twenty-eight brain-injured patients who showed reduced laryngeal elevation and supraglottic penetration or subglottic aspiration during a videofluoroscopic swallowing study (VFSS) were selected. The patients received either conventional dysphagia management (CDM) or CDM with repetitive electrical stimulation of the suprahyoid muscles (ESSM) for 4 weeks. The videofluoroscopic dysphagia scale (VDS) using the VFSS and American Speech-Language-Hearing Association National Outcome Measurement System (ASHA NOMS) swallowing scale (ASHA level) was used to determine swallowing function before and after treatment. RESULTS VDS scores decreased from 29.8 to 17.9 in the ESSM group, and from 29.2 to 16.6 in the CDM group. However, there was no significant difference between the groups (p=0.796). Six patients (85.7%) in the ESSM group and 14 patients (66.7%) in the CDM group showed improvement according to the ASHA level with no significant difference between the ESSM and CDM groups (p=0.633). CONCLUSION Although repetitive neuromuscular electrical stimulation of the suprahyoid muscles did not further improve the swallowing function of dysphagia patients with reduced laryngeal elevation, more patients in the ESSM group showed improvement in the ASHA level than those in the CDM group. Further studies with concurrent controls and a larger sample group are required to fully establish the effects of repetitive neuromuscular electrical stimulation of the suprahyoid muscles in dysphagia patients.

/pdf/electrical-stimulation-of-the-suprahyoid-muscles-in-brain-3i7t142tz7.pdf

Electrical Stimulation of the Suprahyoid Muscles in Brain-injured Patients with Dysphagia: A Pilot Study

Objective. This study aims to investigate the movements of hyolaryngeal structures during the surface electrical stimulation of suprahyoid muscles and to compare these with movements during liquid swallowing.



Materials and methods.  Twelve volunteers without dysphagia participated in this study. Volunteers swallowed 5 mL of diluted barium liquid, which was recorded videofluoroscopically. They then received surface electrical stimulation at midpoints between the chin and the bilateral edges of the hyoid, and movements were again recorded. Two-dimensional motion analysis was performed and displacements of the hyoid and of subglottic air-column and epiglottic rotations were calculated. Movements caused by surface stimulation were compared to those during liquid swallowing.



Results.  Elevation and anterior excursion of the hyoid by electrical stimulation were 66.8% and 45.2% of those during liquid swallowing, respectively, and rotation of the epiglottis by electrical stimulation was 24.0% of that during liquid swallowing. Elevation and anterior excursion of the subglottic air column during liquid swallowing were 24.1 mm and 4.6 mm, respectively, compared with 9.6 mm and 1.9 mm during electrical stimulation. All the movements during electrical stimulation were significantly smaller than those that occurred during liquid swallowing (p < 0.05). Trajectories of the hyoid and larynx during electrical stimulation were smaller than but similar to those that occurred during liquid swallowing.



Conclusion.  This study suggests that surface electrical stimulation of suprahyoid muscles causes the elevation and anterior excursion of hyolaryngeal structures, as is observed during normal physiologic swallowing, although the movements involved were smaller. Further studies are required to determine the effect of synchronized electrical stimulation on dysphagia patients with reduced laryngeal elevation to allow the development of a swallow-assisting neural orthosis.

Sang Jun Kim

Papers

Effect of Surface Electrical Stimulation of Suprahyoid Muscles on Hyolaryngeal Movement