Comparison of Different Electrode Configurations for the oVEMP With Bone-Conducted Vibration

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Abstract

Objectives:

This study was performed to compare three electrode configurations for the ocular vestibular evoked myogenic potentials (oVEMPs)—“standard,” “sternum,” and “nose”—by making use of bone-conducted stimuli (at the level of Fz with a minishaker). In the second part, we compared the test–retest reliability of the standard and nose electrode configuration on the oVEMP parameters.

Design:

This study had a prospective design. Fourteen healthy subjects participated in the first part (4 males, 10 females; average age = 23.4 (SD = 2.6) years; age range 19.9 to 28.3 years) and second part (3 males, 11 females; average age = 22.7 (SD = 2.4) years; age range 20.0 to 28.0 years) of the study. OVEMPs were recorded making use of a hand-held bone conduction vibrator (minishaker). Tone bursts of 500 Hz (rise/fall time = 2 msec; plateau time = 2 msec; repetition rate = 5.1 Hz) were applied at a constant stimulus intensity level of 140 dB FL.

Results:

PART 1: The n10–p15 amplitude obtained with the standard electrode configuration (mean = 15.8 μV; SD = 6.3 μV) was significantly smaller than the amplitude measured with the nose (Z = −3.3; p = 0.001; mean = 35.0 μV; SD = 19.1 μV) and sternum (Z = −3.3; p = 0.001; mean = 27.1 μV; SD = 12.2 μV) electrode configuration. The p15 latency obtained with the nose electrode configuration (mean = 14.2 msec; SD = 0.54 msec) was significantly shorter than the p15 latency measured with the standard (Z = −3.08; p = 0.002) (mean = 14.9 msec; SD = 0.75 msec) and sternum (Z = −2.98; p = 0.003; mean = 15.4 msec; SD = 1.07 msec) electrode configuration. There were no differences between the n10 latencies of the three electrode configurations. The 95% prediction intervals (given by the mean ± 1.96 * SD) for the different interocular ratio values were [−41.2; 41.2], [−37.2; 37.2], and [−25.9; 25.9] for standard, sternum, and nose electrode configurations, respectively. PART 2: Intraclass correlation (ICC) values calculated for the oVEMP parameters obtained with the standard electrode configuration showed fair to good reliability for the parameters n10–p15 amplitude (ICC = 0.51), n10 (ICC = 0.52), and p15 (ICC = 0.60) latencies. The ICC values obtained for the parameters acquired with the nose electrode configuration demonstrated a poor reliability for the n10 latency (ICC = 0.37), a fair to good reliability for the p15 latency (ICC = 0.47) and an excellent reliability for the n10–p15 amplitude (ICC = 0.85).

Conclusions:

This study showed the possible benefits from alternative electrode configurations for measuring bone-conducted-evoked oVEMPs in comparison with the standard electrode configuration. The nose configuration seems promising, but further research is required to justify clinical use of this placement.

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