Vestibular Testing: Patient Perceptions, Morbidity, and Opportunity Costs

Characterization of Optokinetic Nystagmus in Healthy Participants With a Novel Oculography Device

OBJECTIVE

To develop a proof-of-concept smart-phone-based eye-tracking algorithm to assess non-pathologic optokinetic (OKN) nystagmus in healthy participants. Current videonystagmography (VNG) is typically restricted to in-office use, and advances in portable vestibular diagnostics would yield immense public health benefits.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary academic medical center.

METHODS

Healthy participants (n = 39) without dizziness or vertigo were recruited. A smart-phone attached to a custom head stabilization device illuminated by a white LED circuit was used to record nystagmus induced with a 30 frames per second OKN stimulus over a 60-second period. A centroid tracking algorithm was created to detect slow-phase velocity (SPV) of horizontal nystagmus in a diverse subject cohort in a variety of lighting conditions. Nystagmus recordings were compared to those obtained with a standard VNG system.

RESULTS

Non-pathologic nystagmus from an OKN stimulus was measured across multiple lighting conditions, with high signal-to-noise ratios (SNR) and mean SPV 22.13 ± 5.26°/s. Nystagmus SPV was not significantly different between the device and standard VNG system (t = -0.5, P = .6). Lighting conditions produced SNRs of 57.30 (ideal), 50.59 (backlit), 51.33 (side-lit), 49.28 (dark), 54.52 (outdoor lighting).

CONCLUSION

We demonstrate the feasibility of a novel portable oculography system in the detection of non-pathologic nystagmus in healthy subjects. Future applications of this system include: (1) to obtain real-time measurements of nystagmus during an acute vertigo attack; (2) to test patients unable or unwilling to present to a specialized vestibular laboratory; (3) to efficiently repeat testing overtime; (4) to improve accessibility of vestibular testing.

Bedside Neuromodulation of Persistent Pain and Allodynia with Caloric Vestibular Stimulation

BACKGROUND

Caloric vestibular stimulation (CVS) is a well-established neurological diagnostic technique that also induces many phenomenological modulations, including reductions in phantom limb pain (PLP), spinal cord injury pain (SCIP), and central post-stroke pain.

OBJECTIVE

We aimed to assess in a variety of persistent pain (PP) conditions (i) short-term pain modulation by CVS relative to a forehead ice pack cold-arousal control procedure and (ii) the duration and repeatability of CVS modulations. The tolerability of CVS was also assessed and has been reported separately.

METHODS

We conducted a convenience-based non-randomised single-blinded placebo-controlled study. Thirty-eight PP patients were assessed (PLP, n = 8; SCIP, n = 12; complex regional pain syndrome, CRPS, n = 14; non-specific PP, n = 4). Patients underwent 1-3 separate-day sessions of iced-water right-ear CVS. All but four also underwent the ice pack procedure. Analyses used patient-reported numerical rating scale pain intensity (NRS-PI) scores for pain and allodynia.

RESULTS

Across all groups, NRS-PI for pain was significantly lower within 30 min post-CVS than post-ice pack (p < 0.01). Average reductions were 24.8% (CVS) and 6.4% (ice pack). CRPS appeared most responsive to CVS, while PLP and SCIP responses were less than expected from previous reports. The strongest CVS pain reductions lasted hours to over three weeks. CVS also induced substantial reductions in allodynia in three of nine allodynic CRPS patients, lasting 24 h to 1 month. As reported elsewhere, only one patient experienced emesis and CVS was widely rated by patients as a tolerable PP management intervention.

CONCLUSIONS

Although these results require interpretative caution, CVS was found to modulate pain relative to an ice pack control. CVS also modulated allodynia in some cases. CVS should be examined for pain management efficacy using randomised controlled trials.

Coding and Reimbursement for Vestibular Tests by the U.S. Centers for Medicare and Medicaid Services (CMS)

Coding and insurance reimbursement is a part of the healthcare system in the United States but is subject to periodic modifications. In addition to changes in the evaluation and management (E/M) codes that took effect in 2021, there are some differences in coding for some diagnostic vestibular function test procedures. Two new codes for vestibular myogenic evoked potential testing were added and previous codes for auditory evoked potential codes 92585 and 92586, which some facilities had used to bill for vestibular myogenic evoked potential testing, have been eliminated. This article outlines the current state of coding and reimbursement by CMS for vestibular procedures.

Efficient Use of Vestibular Testing

While the majority of vestibular disorders may be diagnosed solely on clinical grounds, a variety of clinical scenarios exist in which objective functional assessment of the vestibular system provides data that facilitate diagnosis and treatment decisions. There exists a veritable armamentarium of sophisticated vestibular test modalities, including videonystagmography, rotary chair testing, video head impulse testing, and vestibular-evoked myogenic potentials. This article aims to help clinicians apply an accessible decision-making rubric to identify the clinical scenarios that may and may not benefit from data derived from specific vestibular function tests.

Perspectives: Evaluation of Older Adult Cochlear Implant Candidates for Fall Risk in a Developing Country Setting

Dizziness, vertigo, and falls are common in older adults. Data suggest that cochlear implant candidates are no different and could be argued to be at elevated risk due to the presence of hearing loss and likely vestibular involvement. Perspectives contextualizes current testing and screening paradigms for vestibular deficits and fall risk and suggests a protocol suitable for use in developing country settings.

Vestibular Thresholds: A Review of Advances and Challenges in Clinical Applications

Vestibular disorders pose a substantial burden on the healthcare system due to a high prevalence and the severity of symptoms. Currently, a large portion of patients experiencing vestibular symptoms receive an ambiguous diagnosis or one that is based solely on history, unconfirmed by any objective measures. As patients primarily experience perceptual symptoms (e.g., dizziness), recent studies have investigated the use of vestibular perceptual thresholds, a quantitative measure of vestibular perception, in clinical populations. This review provides an overview of vestibular perceptual thresholds and the current literature assessing use in clinical populations as a potential diagnostic tool. Patients with peripheral and central vestibular pathologies, including bilateral vestibulopathy and vestibular migraine, show characteristic changes in vestibular thresholds. Vestibular perceptual thresholds have also been found to detect subtle, sub-clinical declines in vestibular function in asymptomatic older adults, suggesting a potential use of vestibular thresholds to augment or complement existing diagnostic methods in multiple populations. Vestibular thresholds are a reliable, sensitive, and specific assay of vestibular precision, however, continued research is needed to better understand the possible applications and limitations, especially with regard to the diagnosis of vestibular disorders.

Impact and Cost Effectiveness of Videonystagmography

Objective:

Videonystagmography (VNG) is a commonly ordered test to evaluate patients with vestibular complaints. To date, there are no evidence-based guidelines for evaluating patients presenting with vestibular symptoms. This study evaluates the cost effectiveness of VNG and the impact of VNG findings on patient management.

Methods:

Patient charts were reviewed from 3 institutions to collect the pre- and post-VNG ICD-9/10 diagnosis and treatment plan. VNG findings were recorded to calculate the incidence of abnormal findings and the incidence of change in diagnosis and/or treatment plan. The cost effectiveness of VNG was estimated based on these calculations.

Results:

A total of 120 patient charts were reviewed. 69/120 (57.5%; 95% CI: 48.2%-66.5%) patients had abnormal findings on their VNG. A change in diagnosis was noted in 24/120 (20.0%; 95% CI: 13.3%-28.3%) patients. A change in treatment plan was noted in 62/120 (51.7%; 95% CI: 42.4%-60.9%) patients, and 11/120 (9.2%; 95% CI: 4.7%-15.8%) had a change in diagnosis that led to change in treatment plan. Using the average Medicare reimbursement for VNG, the cost effectiveness analysis showed a cost of $869.57 per VNG with abnormal findings and a cost of $5454.55 per VNG that lead to a change in diagnosis and treatment plan.

Conclusions:

VNG findings may not result in changes in clinical diagnosis. However, VNG is impactful at influencing treatment plan changes. VNG results are beneficial for counseling patients, guiding treatment plans, and managing patient expectations. When there is a clear indication, VNG testing can be cost effective in managing patients presenting with vestibular symptoms.

Clinical Practice Guideline: Ménière's Disease

OBJECTIVE

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid (endolymph) volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Conventional imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many and typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

Cortical modulation of nociception by galvanic vestibular stimulation: A potential clinical tool?

OBJECTIVE

Vestibular afferents converge with nociceptive ones within the posterior insula, and can therefore modulate nociception. Consistent with this hypothesis, caloric vestibular stimulation (CVS) has been shown to reduce experimental and clinical pain. Since CVS can induce undesirable effects in a proportion of patients, here we explored an alternative means to activate non-invasively the vestibular pathways using innocuous bi-mastoid galvanic stimulation (GVS), and assessed its effects on experimental pain.

METHODS

Sixteen healthy volunteers participated in this study. Experimental pain was induced by noxious laser-heat stimuli to the left hand while recording pain ratings and related brain potentials (LEPs). We evaluated changes of these indices during left- or right-anodal GVS (cathode on contralateral mastoid), and contrasted them with those during sham GVS, optokinetic vestibular stimulation (OKS) using virtual reality, and attentional distraction to ascertain the vestibular-specific analgesic effects of GVS.

RESULTS

GVS elicited brief sensations of head/trunk deviation, inoffensive to all participants. Both active GVS conditions showed analgesic effects, greater for the right anodal stimulation. OKS was helpful to attain significant LEP reductions during the left-anodal stimulation. Neither sham-GVS nor the distraction task were able to modulate significantly pain ratings or LEPs.

CONCLUSIONS

GVS appeared as a well-tolerated and powerful procedure for the relief of experimental pain, probably through physiological interaction within insular nociceptive networks. Either isolated or in combination with other types of vestibular activation (e.g., optokinetic stimuli), GVS deserves being tested in clinical settings.

Endre Hőgyes (1847-1906), Forgotten Father of the Vestibulo-Ocular Reflex

OBJECTIVE

Throughout the history of vestibular research, the discovery of the vestibulo-ocular reflex in 1881 by Endre Hőgyes (1847-1906) is rarely mentioned. The aim of this study is to review Hőgyes' vestibular research articles, all originally written in Hungarian and emphasize their epoch-making content.

MAIN DATA SOURCES

Hőgyes' vestibular publications, originally written in Hungarian, which describe various eye movements of the rabbit in response to vestibular stimulation by rotation about three axes.

RESULTS

Hőgyes was the first to use a three-axis turntable on an experimental animal, in this case a rabbit. He found that depending on the plane of rotation, different types of binocular eye movements were produced. He then demonstrated by destructive and excitatory experiments, the anatomical pathways and the physiological function producing this phenomenon. Ultimately, he explained the exact connections between the inner ear labyrinth and certain muscle contractions during eye movements. He identified this pathway as the "associating center of the ocular movements," later defined as the vestibulo-ocular reflex. Hőgyes' discovery was only superficially noted during his lifetime and ignored after his death.

CONCLUSION

Hőgyes was the first to demonstrate the vestibulo-ocular reflex. He was forgotten during the ensuing 140 years probably because his articles were appeared only in Hungarian and because a short time later, Róbert Bárány's award of the Nobel Prize overshadowed many of Bárány's predecessors and contemporaries, including Hőgyes and relegated them to the background.