Test-retest reliability of p13n23 and n34p44 components of vestibular evoked myogenic potentials in a large healthy population.

OBJECTIVE: The aim of this study is to evaluate the reliability of the VEMP characteristics recorded in a large number of healthy subjects. METHODS: VEMP response was obtained on 75 healthy volunteers. Thirty-nine (39) of them were males and 36 were females. Their age varied between 25 and 63 years (mean value 43). Recording was achieved using monaural acoustic stimulation and ipsilateral muscle contraction. Latencies of p13, n23, n34, p44 peaks, p13n23 and n34p44 amplitudes and the interaural amplitude differences (IAD) were assessed. RESULTS: The stability of latencies, amplitudes of the first p12-n23 and second n34-p44 waveforms was verified. The second complex was present in 76%. No factor indicates statistically significant side difference for both runs. IAD variable was not statistically different from zero in all cases. Results show very good reliability for amplitudes, good for some latencies, poor for some other latencies and IAD34-44 and very poor for IAD13-23. No strong and significant correlations were also found between IAD34-44 and IAD13-23 and between p13n23 and n34p44 amplitudes. CONCLUSION: It is the first time that optimal latencies and amplitudes for early and late components of VEMP are described in a large sample of healthy subjects. The p13, n23, n34 and p44 latencies and p13-n23, and n34-p44 amplitudes were reliable, verifying that the method is reproducible and feasible. The IAD13-23 has the disadvantage of low reliability.

Vestibular evoked myogenic potential eliciting in normal subjects: comparison of four different methods.

OBJECTIVE: Vestibular evoked myogenic potential (VEMP) recording is a new method for testing the otolith receptors and vestibulospinal pathways. The aim of this study was to evaluate the characteristics of VEMP using four different techniques to find reasons to prefer one type of recording over the others. MATERIAL AND METHODS: Twenty healthy persons, 10 males and 10 females with ages ranging from 20 to 57 years (mean age 41 years), were enrolled in this study. Eliciting of VEMPs by using monaural or binaural acoustic stimulation and unilateral or bilateral SCM contraction was evaluated; 105 dB NHL acoustic stimulation consisting of 145 dB rarefaction clicks was applied. Latencies of p13, n23, n34, p44 peaks; amplitudes p13-n23 and n34-p44; and interaural amplitude differences (IADs) were assessed. RESULTS: All four methods elicited constant and evident waveforms. The reliability coefficients of amplitudes were high for all four methods and for both waves. However, the higher scores of reliability appeared for the monaural-ipsilateral recording. The results indicated no statistically significant difference between the right and left sides for all four types of VEMP eliciting. No correlation was found between IAD13-23 and IAD34-44 for all four methods. Statistically significant differences were found only for n23 latency among the four methods. CONCLUSIONS: Although no evidence to reject or strongly favour a specific method was found, the monaural-ipsilateral recording was associated with some advantages.