Electromyographic activation patterns during swallowing in older adults

Area of Science:

• Gerontology
• Physiology
• Biomedical Engineering

Background:

• Age-related oropharyngeal muscle weakness, atrophy, and fatty infiltration are potential causes of dysphagia in older adults.
• Limited understanding exists regarding age-related alterations in oropharyngeal muscle activation patterns during swallowing.
• Investigating these patterns is crucial for understanding and potentially mitigating age-related swallowing difficulties.

Purpose of the Study:

• To investigate and compare oropharyngeal muscle activation patterns during swallowing in healthy young and older adults.
• To identify differences in muscle activation strategies related to age, bolus volume, and viscosity.

Main Methods:

• A prospective experimental study involving 40 healthy participants (20 young, 20 older adults).
• Surface electromyography (sEMG) recorded from suprahyoid (SH), retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles.
• sEMG signals analyzed during swallowing of varying water volumes (2cc, 5cc) and a highly viscous fluid, measuring latency, duration, and peak amplitude.

Main Results:

• Both age groups exhibited similar activation sequences (SH, TH, StH) and classified patterns (Type I: monophasic, Type II: pre-reflex and main phase).
• A pre-reflex phase emerged in oropharyngeal and SH muscles with increased volume and viscosity in both groups.
• Type I patterns showed age-related differences with highly viscous fluids, while Type II patterns remained consistent across age groups.

Conclusions:

• Healthy older adults utilize a compensatory pre-reflex muscle activation phase to manage swallowing challenges associated with increased fluid volume and viscosity.
• This adaptive strategy likely counteracts age-related oropharyngeal muscle weakness, preserving swallowing function.
• Understanding these compensatory mechanisms can inform interventions for age-related dysphagia.