The Relationship Between Submental Surface Electromyography and Hyo-Laryngeal Kinematic Measures of Mendelsohn Maneuver Duration

Abstract

Purpose The Mendelsohn Maneuver (MM) is a commonly prescribed technique that is taught to individuals with dysphagia to improve swallowing ability. Due to cost and safety concerns associated with videofluoroscopy (VFS) use, submental surface electromyography (ssEMG) is commonly used in place of VFS to train the MM in clinical and research settings. However, it is unknown whether ssEMG accurately reflects the prolonged hyo-laryngeal movements required for execution of the MM. The primary goal of this study was to examine the relationship among ssEMG duration, duration of laryngeal vestibule closure, and duration of maximum hyoid elevation during MM performance. Method Participants included healthy adults and patients with dysphagia due to stroke. All performed the MM during synchronous ssEMG and VFS recording. Results Significant correlations between ssEMG duration and VFS measures of hyo-laryngeal kinematic durations during MM performance ranged from very weak to moderate. None of the correlations in the group of stroke patients reached statistical significance. Conclusion Clinicians and researchers should consider that the MM involves novel hyo-laryngeal kinematics that may be only moderately represented with ssEMG. Thus, there is a risk that these target therapeutic movements are not consistently being trained.

Kinematic Visual Biofeedback Improves Accuracy of Learning a Swallowing Maneuver and Accuracy of Clinician Cues During Training

“…Their duration target was 2 seconds of increased ssEMG amplitude. Similar to Ding et al (2002), Crary et al (2004), and Azola et al (2015), a specific amplitude target threshold was not established. Instead, we aimed to simulate clinical use of ssEMG biofeedback without simultaneous complex analysis and interpretation of the EMG signal by the participant.…”

“…It is safe, widely available, and less expensive than videofluoroscopy. We used the same ssEMG recording procedures as Azola et al (2015). Bipolar ssEMG electrodes (Dual Bio Amp by AD Instruments) were placed on the left and right sides of the submental muscle group, approximately half way between the hyoid bone and the mentalis of the mandible.…”

“…Raw ssEMG signals were used as visual biofeedback (Figure 1). Participants were oriented to the meaning of changes in the ssEMG signal on the Y-axis (thicker signal means more muscle activity) and to sustain thickness at four times the baseline (rest) signal, as in Azola et al (2015). Participants were also oriented to the time course along the X-axis to improve their interpretation of increasing ssEMG signal thickness for 2 seconds.…”

“…Thus, ssEMG as visual biofeedback might not confirm that certain target therapeutic movements have been attained. This was supported by Azola et al (2015), wherein ssEMG represented less than 40% of hyo-laryngeal movements (duration of hyoid elevation, and laryngeal vestibule closure duration) seen in videofluoroscopy (VF) during Mendelsohn maneuver training in healthy adults and in individuals with dysphagia due to stroke (6). This discrepancy in measurement specificity between ssEMG and videofluoroscopy outcomes likely exists because the submental muscle group is also active during other co-occurring swallowing functions, including lingual movement and stabilization against infrahyoid musculature (7,8).…”

Kinematic Visual Biofeedback Improves Accuracy of Swallowing Maneuver Training and Accuracy of Clinician Cues During Training in Stroke Patients with Dysphagia

“…Given the barriers in using VF or FEES for therapeutic purposes, submental surface EMG (ssEMG) is commonly employed in dysphagia management as a form of nonkinematic biofeedback because it is widely available, safe, and cost effective . The caveat of ssEMG is that it displays nonkinematic information, meaning that, although it can record and display the activation of muscle groups involved in swallowing, it cannot provide direct visualization of the movements of specific structures essential for airway protection and thus its effectiveness as a visual biofeedback tool in dysphagia management has been questioned . In fact, in a study with concurrent ssEMG and VF, Azola et al showed that when training a swallowing maneuver called the Mendelsohn Maneuver (involves prolonging elevation of the hyoid bone and larynx), changes in ssEMG while performing this maneuver represented less than 40% of the actual kinematics of the hyoid bone or larynx in both healthy adults and individuals poststroke .…”