Mylohyoid and sternohyoid muscles electromyography (EMG)‎ in obstructive sleep apnea syndrome

Abstract EN

This study was conducted on fifteen patients, eleven men and four women, aged 30-50 years, with obstructive sleep apnea syndrome (OSA) and ten healthy controls.

We studied the electromyographic (EMG) activity of the mylohyoid and stermohyoid muscles as examples of supra and infrahyoid muscles respectively.

This was performed at rest, during swallowing and with deep inspiration to investigate their function in controlling the position of the hyoid bone in OSA patients as compared to controls.

EMG was done using concentric needle electrodes.

The following parameters were estimated as a function of muscle force: the mean amplitude of the motor unit action potentials (MUAPs) (v), Turns/second T/S, the mean amplitude per second (A/Sec) (mv/sec) and the ratio between turns/sec and mean amplitude (T/A).

There was a significant decrease in the mean amplitude of MUAPs of both muscles at resting activity in OSA patients than in normal controls (p<0.01).

During swallowing and deep inspiration, analysis of the interference pattern (IP) revealed a statistically significant reduction in the mean amplitude MUAPs, T/S, A/sec in OSA patients than in normals (p<0.001).

In addition, the mean ratios of IP of the mylohyoid under swallowing and deep inspiration were significantly higher in OSA patients than those of normals (p<0.05).

The mean ratios of the sternohyoid were also higher (but insignificant statistically p>0.05).

We concluded that needle EMG revealed weakness of both supra and infrahyoid muscles in OSA patients.

This hypotonic weakness could be related to a myogenic cause and results in disturbances in the pharyngeal vertical tension, which controls the position of the hyoid bone and is subsequently involved in the reduction of the pharyngeal collapsibility.