Influence of head acceleration on ocular vestibular-evoked myogenic potentials via skull vibration at Fz versus Fpz sites

Abstract

Objective: This study applied bone vibration (BV) stimulation to the Fz and Fpz sites to investigate the influence of head acceleration on the ocular vestibular-evoked myogenic potentials (oVEMPs). Design: Prospective study. Study Sample: Fourteen healthy subjects underwent oVEMP tests combined with real-time triaxial accelerometry. Results: Under BV stimulation from a vibrator to the Fz and Fpz sites, acceleration magnitudes along x-, y- or z-axis did not significantly differ between the two sites. The mean nI and pI latencies of the oVEMPs stimulated at Fz were significantly earlier than those at Fpz. However, no statistical differences existed in the nI-pI interval and amplitude between the two sites. A blunt or double peak nI configuration was noted in three subjects (22%) when tapping at Fpz, but not at Fz, likely because different muscles contributing to the oVEMPs. Conclusion: While both Fz and Fpz are effective sites for generating an oVEMP, the variation in human skull shapes and properties will lead to different acceleration profiles being transmitted to the vestibular apparatus. These differing stimuli may lead to different oVEMP profiles, so if one site does not produce the expected response, the clinician should try the other site.

Key Words::

• bone vibration
• interaural acceleration
• ocular vestibular-evoked myogenic potential
• triaxial accelerometry

Acknowledgement

This study was supported by a research grant (NSC 99 - 2314-B002 - 049-MY3) from the National Science Council, Taipei, Taiwan.

Declaration of interest: The authors report no conflicts of interest. The author (Young) is responsible for the content of the paper.