Objective To determine the role played by the tensor veli palatini and levator veli palatini muscles (mTVP and mLVP, respectively) in eustachian tube (ET) opening.
Design Prospective study.
Setting Research laboratories at a tertiary care hospital.
Patients Fifteen healthy adults with normal middle ears and documented ET openings.
Interventions Submental and ground surface electrodes were placed. After anesthetizing and decongesting the nasal passages, paired electromyographic needle electrodes were inserted into both the mTVP and mLVP on the test side. A microphone was placed into the ipsilateral ear canal and the probe from a sound generator was introduced into the opposite nostril. A 45° telescope was used on the test side to video-record the soft palate and ET movements while the individual swallowed.
Main Outcome Measures Concurrent recordings of the ET openings by sonotubometry, the electromyographic activity for the LVP, TVP, and submental muscles, and video of the nasopharyngeal orifice of the ET during swallowing.
Results During swallowing, the median peak amplitude and duration of ET openings by sonotubometry were 30.6 mV and 196 milliseconds, respectively. For the mLVP and mTVP, the median peak amplitudes were 0.33 and 0.82 mV, and peak durations were 131 and 85 milliseconds, respectively. The mean onsets of muscle activity referenced to the sonotubometry peak amplitude were −0.28, −0.24, and −0.14 milliseconds for the mLVP, mTVP, and submental muscles, respectively. Video recording of ET movements were consistent with the timing of these events.
Conclusions The mTVP activity had a shorter duration but greater amplitude than the mLVP activity and was associated with peak ET opening by sonotubometry. The mLVP activity occurred before that of the mTVP, the submental muscle group, and peak ET opening. The mLVP contractions were associated with movements of the soft palate, anterior ET orifice, and rotation of the ET cartilage.