Optimum Number of Sweeps in Clinical OVEMP Recording; How Many Sweeps are Necessary?

The clinical meaning and significance of OVEMP morphology

PURPOSE

While some OVEMP recordings are morphologically straightforward, some are poor in appearance, which can create a challenge, as they often require a "second look" by another experienced assessor. Even OVEMPs in normal subjects are sometimes poorly formed, but we wondered if the morphological assessment of the OVEMP response might provide some additional diagnostic information.

METHODS

A single experienced assessor evaluated the OVEMP recordings of 60 patients referred sequentially to a tertiary care centre, and categorized them as "easy to assess" (i.e. obvious to a minimally trained assessor) or "difficult to assess", often requiring a second look by another experienced assessor.

RESULTS

In 48 patients, the results were easy to assess (regardless of the actual clinical results) while 12 were classified as "difficult". This figure reflected the rate of morphologically poor responses we found in our population of normative data.

CONCLUSION

Our clinical concern is that many centres have given up relying on OVEMP assessment because the morphology of the wave may be challenging to interpret. OVEMP assessment often calls for a "second look", requiring a collaboration between two experienced assessors. It seems that this feature may not be diagnostically useful and poor OVEMP morphology may present a challenge in interpretation, but this should not be used as a reason to defer OVEMP testing.

Vestibular Evoked Myogenic Potentials and Postural Control in Adults with Age-Related Hearing Loss

BACKGROUND

 Age-related changes to auditory function have been attributed to, through histopathological study, specific degradation of the sensory, supporting, and afferent structures of the cochlea. Similar to age-related hearing loss (ARHL), age-related changes to the vestibular sensory and supporting structures with specific degeneration of the saccule, utricle, otoconia, primary vestibular afferents have also been noted. Significant decreases in postural control with age are also well-documented in the literature attributed to multifactorial changes in function.

PURPOSE

 The purpose of this study is to further evaluate the association of ARHL and saccule/utricle function as measured by VEMPs and postural control measures.

STUDY SAMPLE

 Audiologic, vestibular and postural control results from 34 participants were analyzed. The age range was from 50 to 70 years old with 16 males and 18 females. Group 1 consisted of 33 ears from participants age 50-70 with normal hearing with average age of 60.8 years (sd 6.287 years) and an average speech-frequency PTA of 14.8 dB HL. Group 2 consisted of 27 ears from participants age 50-70 years with ARHL and an average age of 62.9 years (sd 4.984 years) with an average speech-frequency PTA of 39.9 dB HL.

DATA COLLECTION AND ANALYSIS

 Independent samples t-tests were used to assess group mean differences for dependent variables. The independent variable was group with 2 levels (normal hearing, ARHL). The dependent variables were cVEMP P1/N1 Amplitude, cVEMP P1 Latency, cVEMP N1 Latency, cVEMP P2 Latency, oVEMP N1/P1 Amplitude, oVEMP N1 Latency, and oVEMP P1 Latency. Additional analyses were completed using Pearson correlation to evaluate the relationship of audiometric findings to the dependent variables.

RESULTS

 Results indicated significantly decreased cVEMP P1/N1 amplitude and oVEMP N1/P1 amplitude adults 50-70-years of age with ARHL compared with their normal counterparts. Significant correlations were also found for audiometric results and both cVEMP and oVEMP measures.

CONCLUSIONS

 Overall, the results of this study describe concomitant auditory and vestibular degeneration as measured by audiometric testing and vestibular function testing involving the saccule and to a lesser degree the utricle.

Performing and analysing tone-induced cervical and ocular vestibular-evoked myogenic potentials in traumatic and non-traumatic vestibular pathology

OBJECTIVE

This paper discusses our technique of carrying out cervical and ocular vestibular-evoked myogenic potential testing in a single position. The described technique allows for a symmetrical, natural flexion of the neck muscles, which is helpful as many of our patients have suffered traumatic deceleration injures.

METHODS

Patients with suspected vestibular pathology referred by specialists were sequentially assessed in a tertiary referral neuro-otology unit within a teaching hospital using our technique and our previously established normative database. All patients underwent standardised vestibular assessment in addition to cervical and ocular vestibular-evoked myogenic potential assessment. Our normative data are in keeping with that reported by other centres.

RESULTS

Many of the patients had abnormal vestibular-evoked myogenic potentials, which is in line with a history suggesting otolithic disease.

CONCLUSION

Both cervical and ocular vestibular-evoked myogenic potentials offer several parameters for detecting abnormalities. The technique reported enables us to assess patients in an accurate fashion whether or not they have suffered traumatic neck injuries.