Vestibular-evoked myogenic potentials recorded from miniature pigs and rats

To report vestibular evoked myogenic potentials from different recording sites (neck extensor or masseter muscles) in miniature pigs and rats.

Potentials were recorded using 1000 Hz tone bursts from the neck extensor muscle or masseter muscle in normal adult Bama miniature pigs and rats anesthetized with 3% pentobarbital sodium and Sumianxin II.

At 80 dB SPL, the first positive wave (P wave) of VEMPs was recognizable in 58% of rats with a latency of 6.45 ± 0.23 ms and an amplitude of 1.45 ± 0.49 μV when recorded from the neck extensor muscle, and in 50% of rats with a latency of 6.38 ± 0.34 ms and an amplitude of 1.57 ± 0.35 μV when recorded from the masseter muscle. In miniature pigs, at the same stimulus intensity, P wave was recognizable in 58% of the animals with a latency of 7.65 ± 0.64 ms and an amplitude of 1.66 ± 0.34 μV when recorded from the neck extensor muscle, and in 50% of the animals with a latency of 7.65 ± 0.64 ms and an amplitude of 0.31 ± 0.28 μV when recorded from the masseter muscle.

VEMP can be induced from both neck extensor and masseter muscles in the miniature pig and rat. For a given species, the site of recording affects P wave induction rate and amplitude but not latency. Consistency and repeatability analysis suggests that the masseter muscle is a better recording site in miniature pigs while the cervical extensor is a better recording site in rats. For a given recording site, both latency and amplitude of the P wave are slightly greater in miniature pigs than in rats.