Clinical Measurement of Pharyngeal Surface Electromyography

Electroacupuncture improves swallowing function in a post-stroke dysphagia mouse model by activating the motor cortex inputs to the nucleus tractus solitarii through the parabrachial nuclei

As a traditional medical therapy, stimulation at the Lianquan (CV23) acupoint, located at the depression superior to the hyoid bone, has been shown to be beneficial in dysphagia. However, little is known about the neurological mechanism by which this peripheral stimulation approach treats for dysphagia. Here, we first identified a cluster of excitatory neurons in layer 5 (L5) of the primary motor cortex (M1) that can regulate swallowing function in male mice by modulating mylohyoid activity. Moreover, we found that focal ischemia in the M1 mimicked the post-stroke dysphagia (PSD) pathology, as indicated by impaired water consumption and electromyographic responses in the mylohyoid. This dysfunction could be rescued by electroacupuncture (EA) stimulation at the CV23 acupoint (EA-CV23) in a manner dependent on the excitatory neurons in the contralateral M1 L5. Furthermore, neuronal activation in both the parabrachial nuclei (PBN) and nucleus tractus solitarii (NTS), which was modulated by the M1, was required for the ability of EA-CV23 treatment to improve swallowing function in male PSD model mice. Together, these results uncover the importance of the M1-PBN-NTS neural circuit in driving the protective effect of EA-CV23 against swallowing dysfunction and thus reveal a potential strategy for dysphagia intervention.

Numerical and Experimental Analysis of Inhalation Airflow Dynamics in a Human Pharyngeal Airway

This paper presents a computational and experimental study of steady inhalation in a realistic human pharyngeal airway model. To investigate the intricate fluid dynamics inside the pharyngeal airway, the numerical predicted flow patterns are compared with in vitro measurements using Particle Image Velocimetry (PIV) approach. A structured mesh with 1.4 million cells is used with a laminar constant flow rate of 10 L/min. PIV measurements are taken in three sagittal planes which showed flow acceleration after the pharynx bend with high velocities in the posterior pharyngeal wall. Computed velocity profiles are compared with the measurements which showed generally good agreements with over-predicted velocity distributions on the anterior wall side. Secondary flow patterns on cross-sectional slices in the transverse plane revealed vortices posterior of pharynx and a pair of secondary flow vortexes due to the abrupt cross-sectional area increase. Finally, pressure and flow resistance analysis demonstrate that greatest pressure occurs in the superior half of the airway and maximum in-plane pressure variation is observed at the velo-oropharynx junction, which expects to induce a high tendency of airway collapse during inhalation. This study provides insights of the complex fluid dynamics in human pharyngeal airway and can contribute to a reliable approach to assess the probability of flow-induced airway collapse and improve the treatment of obstructive sleep apnea.

Electrical bioimpedance measurement as a tool for dysphagia visualisation

A non-invasive and portable bioimpedance method and a device for detecting superior to inferior closure of the pharynx during swallowing have been developed. The 2-channel device measures electric impedance across the neck at two levels of the pharynx via injected currents at 40 and 70 kHz. The device has been trialled on both healthy and dysphagic subjects. Results from these trials revealed a relationship (r = 0.59) between the temporal separation of the second peaks in the bioimpedance waveforms and descending pressure sequence in the pharynx as measured by pharyngeal manometry. However, these features were only clearly visible in the bioimpedance waveforms for 64% of swallows. Further research is underway to improve the bioimpedance measurement reliability and validate waveform feature correlation to swallowing to maximise the device's efficacy in dysphagia rehabilitation.

A novel emergency department dysphagia screen for patients presenting with acute stroke

OBJECTIVES

Dysphagia is a common complication for emergency department (ED) patients presenting with acute stroke (AS). Recent stroke recommendations have suggested that EDs screen patients with AS for dysphagia prior to administering anything by mouth. This study sought to develop and test a novel ED dysphagia screen to be used in this population.

METHODS

A multidisciplinary approach was used to create a novel dysphagia screen performed by ED nurses during the initial evaluation of patients with suspected AS. The screen consists of five questions of which any single affirmative answer signified possible dysphagia. A prospective cohort study was conducted to evaluate the performance of this screen in detecting dysphagia after AS. Patients were followed for 30 days, and true dysphagia was determined if the patient had an abnormal modified barium swallow study (MBS), had placement of a feeding tube, or was placed on a dysphagia diet after assessment by a speech pathologist. The authors performed a substudy to determine agreement using a blinded kappa (κ) assessment with a convenience sample of 40 patients.

RESULTS

Over a 21-month period, 283 patients met eligibility for analysis. The rate of cerebral infarction in this cohort was 245 (87%). The rates for true dysphagia, pneumonia, and death were 91 (32%), 26 (9%), and 18 (6%), respectively. The dysphagia screen had a sensitivity of 95% (95% confidence [CI] = 88% to 98%) and a negative likelihood ratio of 0.1 (95% CI = 0.04 to 0.2). The inter-rater agreement assessed by kappa was substantial (0.69, 95% CI = 0.55 to 0.83).

CONCLUSIONS

These data suggest that this dysphagia screen may be a valuable tool for detecting dysphagia in ED patients presenting with AS. The simple screen can be performed by nursing personnel and appears to perform well with good agreement. Given the overall rate of dysphagia in one-third of AS patients, the use of an ED dysphagia screen appears warranted.

Pharyngeal pressure generation during tongue-hold swallows across age groups

PURPOSE

To compare the effects of the tongue-hold swallowing maneuver on pharyngeal pressure generation in healthy young and elderly research volunteers.

METHOD

Sixty-eight healthy research volunteers (young, n = 34, mean age = 26.8 years, SD = 5.5; elderly, n = 34, mean age = 72.6 years, SD = 4.8; sex equally represented) performed 5 noneffortful saliva swallows and 5 tongue-hold swallows each. Amplitude and duration of pharyngeal pressure were investigated during both swallowing conditions with solid-state pharyngeal manometry at the level of the oropharynx, hypopharynx, and upper esophageal sphincter (UES).

RESULTS

At both pharyngeal levels, tongue-hold swallows produced lower peak pressure compared with saliva swallows. During tongue-hold swallows, UES relaxation pressure was increased in the elders, whereas the younger group displayed a trend toward reduced relaxation pressure. Elderly individuals produced pressure longer during control swallows in the oropharynx and hypopharynx than young individuals.

CONCLUSIONS

The tongue-hold maneuver affects oropharyngeal and hypopharyngeal pressure in the young and elders in similar ways, whereas effects on UES peak relaxation pressure differ between age groups. Reduced pharyngeal peak pressure and increased UES relaxation pressure underscore the notion that tongue-hold swallows should not be performed when bolus is present. Long-term training effects remain to be investigated.