Cervical vestibular-evoked myogenic potentials in patients with multiple sclerosis: sensitive in detecting brainstem involvement?

Diagnostic value of vestibular evoked myogenic potentials in benign paroxysmal positional vertigo

OBJECTIVES

Vestibular evoked myogenic potentials (VEMPs) are useful for studying the disturbances along nerve pathways implicated in the transmission of neurological information from otolithic organs related to vestibular function. This study aims to determine the differences in VEMPs in patients affected with benign paroxysmal positional vertigo (BPPV).

METHODS

We recruited 36 patients, 9 diagnosed with recurrent BPPV (rBPPV), 9 with only one episode of vertigo (iBPPV), and 18 as a control group. We performed cervical and ocular VEMPs (cVEMPs and oVEMPs).

RESULTS

We observed differences in asymmetry ratio, which was 41.82% in cVEMPs in iBPPV and 68.27% in oVEMPs in rBPPV, while no asymmetry was found in control cases. Also, there was a lack of both VEMP responses in 22.2% of cases and an absence of cVEMP in 11.1% in iBPPV; in rBPPV, 11.1 % presented no responses in cVEMPs or oVEMPs, 22.2% showed no oVEMP, and 11.1% showed no cVEMP. These values were normal in the control group.

CONCLUSION

The value of VEMPs in BPPV demonstrates the implication of vestibular damage, mainly utricle damage. For better sensitivity in detecting otolith abnormalities, we should perform oVEMPs and cVEMPs in recurrent BPPV and early stages of BPPV.

Effects of multiple sclerosis on the audio-vestibular system: a systematic review

OBJECTIVE

Systematically investigate the effects of multiple sclerosis (MS) on the audio-vestibular system.

METHODS

Systematic review of literature investigating audio-vestibular conditions in persons with MS (PwMS) aged ≥18 years. PubMed, Scopus, NICE and Web of Science were searched. Randomised controlled trials, and cohort, case-control, observational and retrospective studies in English, published from 2000 to 21 November 2021, evaluated PwMS with at least one outcome (pure tone audiometry, auditory brainstem response, otoacoustic emissions, cortical auditory evoked potentials, functional MRI assessing auditory function, vestibular evoked myogenic potentials, videonystagmography, electronystagmography, posturography, rotary chair, gaps in noise, word discrimination scores, duration pattern sequence test), were included. Study selection and assessments of bias were independently conducted by two reviewers using the Risk of Bias Assessment Tool for Non-randomized Studies, Newcastle-Ottawa Scale (NOS) and the NOS adapted for cross-sectional studies.

RESULTS

35 studies were included. Auditory function was evaluated in 714 PwMS and 501 controls, vestibular function was evaluated in 682 PwMS and 446 controls. Peripheral auditory function results were contradictory between studies; some found abnormalities in PwMS, and others found no differences. Tests of brainstem and central auditory functions were more consistently found to be abnormal in PwMS. Most vestibular tests were reported as abnormal in PwMS, abnormalities were either peripheral or central or both. However, quantitative analyses could not be performed due to discrepancies between studies in results reporting, test stimulus and recording parameters.

CONCLUSIONS

Although abnormal results on auditory and vestibular tests were noted in PwMS, specific effects of MS on the audio-vestibular system could not be determined due to the heterogeneity between studies that restricted the ability to conduct any quantitative analyses. Further research with consistent reporting, consistent stimulus and consistent recording parameters is needed in order to quantify the effects of MS on the auditory and vestibular systems.

PROSPERO REGISTRATION NUMBER

CRD42020180094.

Impairment of vestibulo-collic reflex and linear vestibulo-ocular reflex in pediatric-onset multiple sclerosis patients

OBJECTIVES

This study aimed to examine the vestibulo-collic reflex (VCR) and linear vestibulo-ocular reflex (lVOR) and their correlation with brain lesions in pediatric-onset multiple sclerosis (POMS).

METHODS

The study group consisted of 17 patients (34 ears) with POMS (mean age 18.73 ± 2.02, mean age at disease onset 14.64 ± 1.36 years), and the control group included 11 age-matched healthy subjects (22 ears). Ocular and cervical Vestibular Evoked Myogenic Potentials (oVEMP and cVEMP) were performed to assess IVOR and VCR pathways. Magnetic Resonance Imaging was evaluated in the study group.

RESULTS

In the POMS group, 47.05 % of oVEMPs and 17.64 % of the cVEMPs were abnormal, while all VEMPs were normal in the control group. The oVEMP amplitude was associated with infratentorial lesion volume (r = -0.459, p = 0.01) and total lesion volume of the brainstem and cerebellum (r = -0.450, p = 0.01). The cVEMP asymmetry ratio was correlated with the deep white matter lesion volume (r = 0.683, p < 0.001). The MVEMP scores were found to correlate only with lesion volumes in the cerebellum (r = 0.488, p = 0.04) and infratentorial region (r = 0.573, p = 0.01).

CONCLUSIONS

Ocular and cervical VEMP abnormalities confirm that lVOR and VCR pathways may be affected in early POMS.

SIGNIFICANCE

Routine use of the VEMP test, especially the oVEMP test is recommended as a useful tool in the follow-up of POMS patients.

What might cervical vestibular-evoked myogenic potential abnormalities mean in essential tremor?

AIM/BACKGROUND

Essential tremor (ET) is one of the most common movement disorders. However, its pathogenesis is unclear. Human vestibular reflexes are essential not only for gait and posture but also for goal-directed voluntary movements. In this study, cervical vestibular-evoked myogenic potentials (cVEMPs), the electrophysiological equivalent of the vestibulo-collic reflex was studied in ET patients to understand the interaction between the tremor network and the vestibular neural pathways.

METHODS

cVEMPs were recorded in 40 ET patients and 40 age and sex-matched healthy controls (HCs). The latencies of peaks p13 and n23 and peak-to-peak amplitude of p13-n23 were measured.

RESULTS

There was no statistically significant difference between the p13 latencies of the HC and ET groups (p 0.79 and p 0.23 for the right and left sides respectively). n23 latency was shortened bilaterally in the ET group (p 0.009 and p 0.02 for the right and left sides respectively). p13-n23 amplitudes of the ET patients were bilaterally reduced when compared with the HC (p <0.001 and p 0.001 for the right and left sides respectively).

CONCLUSION

Information provided by vestibular afferents is crucial in the control of voluntary movements in humans. Despite this silent but significant effect, the role of the vestibular system in movement disorders is often overlooked. In this study, it was found that cVEMP responses reflecting the activity of the vestibulo-collic pathway were affected in ET which can be either caused by dysfunctional structures or pathways responsible from ET or an additional disorder of vestibular information processing in these patients.

Cervical Vestibular Evoked Myogenic Potentials in Idiopathic Intracranial Hypertension

PURPOSE

Idiopathic intracranial hypertension (IIH) is raised intracranial pressure without any identifiable etiology. The inner ear structures are susceptible to cerebrospinal fluid (CSF) pressure changes because of connections between the CSF space and the labyrinth to explain the audiovestibular symptoms, such as pulsatile tinnitus or dizziness, reported in 50% to 60% of these patients. The aim of this study was to investigate the vestibular functions using cervical vestibular evoked myogenic potentials in IIH.

METHODS

Cervical vestibular evoked myogenic potentials were recorded in 30 patients with IIH before lumbar puncture. Thirty healthy volunteers constituted the control group. The latencies of peaks p13 and n23 and peak-to-peak amplitude of p13-n23 were measured.

RESULTS

Responses were gathered bilaterally from all healthy controls. In 30 patients with IIH, 49 responses could be gathered from 60 tests (81.7%). The potential was absent bilaterally in five and unilaterally in one patient. When recorded, the latency and amplitude values of the responses of the patients were not significantly different from the healthy controls (P > 0.005). A correlation between CSF pressure and response persistence could not be determined.

CONCLUSIONS

Cervical vestibular evoked myogenic potentials are affected in patients with IIH and the main finding is the absence of the responses. Increased intracranial pressure causing sound transmission changes within the inner ear can affect the saccular afferents and may end up with absent responses on air-conducted cVEMP recordings. To comment on the correlation between the CSF pressure and cVEMP changes, successive cVEMP recordings with longitudinal CSF pressure monitoring seem necessary.

Enhancing research quality of studies on VEMPs in central neurological disorders: a scoping review

Common pitfalls in vestibular-evoked myogenic potential (VEMP) recording methods have been extensively outlined by several reviews. Conversely, the robustness of research methodology employed for the design and conduct of VEMP studies has never been appraised. To fill this void, we conducted a scoping review to map and evaluate the overall quality of the existing literature on VEMPs in central neurological disorders. Five databases were searched from inception to October 2018 for case-control studies on multiple sclerosis (MS), cerebellar and/or brainstem strokes, Parkinson's disease (PD), migraine, and tumors of the cerebellopontine angle. Study quality was assessed using the Agency for Healthcare Research and Quality criteria (AHRQ). The 11-criteria AHRQ scoring system revealed that PD studies achieved a score of 5/11, migraine and cerebellar and/or brainstem stroke a score of 4/11, MS and tumors of the cerebellopontine angle a score of 3/11. Age was found to be one of the main sources of case-control imbalance: compared with controls, cases were significantly older with a 3.6-yr difference in MS studies, 6 yr in PD, up to 12 yr in stroke and tumors. Regardless of pathological condition, case-control groups were found unmatched also by gender. Post hoc power calculations revealed that 53% of the studies achieved the minimum statistical power of 80%. This scoping review revealed low research quality across the literature on VEMPs in central neurological disorders. Scoping lines are provided on actions to be undertaken in future studies to establish a common methodological platform and enhance the quality of research in this field.NEW & NOTEWORTHY Robust methodology is a prerequisite for any type of research, particularly for observational designs such as those employed in vestibular-evoked myogenic potential (VEMP) research. On these premises, this scoping review provides methodological guidelines to improve validity, accuracy and consistency of clinical outcomes from VEMP studies involving central nervous system disorders. In fact, the high risk for bias that is inherent to poor methodology threatens the validity of the findings of works that are technically sound but methodologically flawed.