Functional assessment of muscle activities during swallowing in healthy subjects and patients with dysphagia

Swallowing disorder is one of the most important complaints of patients with upper motor neuron lesions.The rate of disphagia increases due to elderly subjects and brain injuries in our society Majority of these patients have hidden aspiration. Electromyographic assessment of swallowing can produce indicators of recovery and treatment effectiveness. This study tries to indicate pattern and recruitment of muscle activity in swallowing by surface electromyography.Methods and Materials: Twenty healthy subjects (20-50) and ten subjects with swallowing dysfunction contribute at this study. Activities of bilateral orbicularis oris, buccinator, sternocleidomastoid and anterior region of throat muscles recorded during three stage of liquid swallowing include water, juice and honey by surface electrodes. Value of activity (RMS), duration of activity (Dur), median (Mdf) and band (Banf) frequency of above muscles were measured. Healthy subjects indicated increase of RMS, Dur, Mdf and Banf of muscles, following increase of sweeten and viscose of liquid (P<0.05). Patients had more increase of this findings at oral muscles markedly, whereas Dur of throat muscle showed more increase in time (P<0.05). Comparison of between two groups indicated patients have more Dur time especially at throat muscles (P<0.05) and in contras reduce of activities and frequency parameters than healthy subjects (P<0.05). Patients lean to keep liquid in oral phase and during throat swallow have more limitation. Patients may catch early fatigue and dysfunction for maintenance and keep of liquid particularly in throat region and it redound to change of trajectory of liquid to the respiratory tube. Therefore, rehabilitation protocols must enforce on coordination of oropharengeal muscles and recovery by movement therapy patterns.