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

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.

The Sequence of Swallowing Events During the Chin-Down Posture.

PURPOSE: This study investigated the effect of the chin-down posture on the sequence of swallowing events in healthy adults. METHOD: Sixteen healthy participants performed 45 5-ml thin liquid swallows during videofluoroscopy: 5 neutral head position, 30 chin-down posture, and then 10 neutral head position. Eight swallowing events were measured: the time of hyoid burst, bolus head in the pharynx, bolus tail in the pharynx, laryngeal vestibule closure (LVC), upper esophageal sphincter (UES) opening, bolus head in the UES, bolus tail exiting the pharynx, and laryngeal vestibule opening (LVO). RESULTS: Our key finding is that LVC was one of the first 3 swallowing events in 69% of neutral swallows and in 78% of chin-down swallows (p = .006). Also, LVO occurred last in 14% of chin-down swallows but never occurred last in the preceding neutral swallows (p ≤ .001). Thus, in chin-down swallows, LVC occurred earlier and LVO occurred later. CONCLUSIONS: The chin-down posture may be beneficial for individuals with delayed onset of LVC and reduced duration of the LVC. Future studies are needed to examine this effect in individuals with dysphagia.

The effects of feedback on volitional manipulation of airway protection during swallowing.

Volitional control of autonomic responses, such as heart rate and blood pressure, can be facilitated with the use of augmented feedback. Oropharyngeal swallowing typically includes both volitional and reflexive components, offering a unique opportunity for observing how performance is affected by feedback. Sixteen healthy participants (M age=29 years, SD=10 years) completed multiple trials of a novel airway closure technique during swallowing under one of two conditions: no feedback or feedback. The feedback condition included knowledge of performance and knowledge of results. Only the feedback group improved performance across trials (p=.01), with no difference from baseline seen for the no feedback group (p=.66). These results show that airway closure during swallowing can be volitionally manipulated with augmented feedback.