Utricular function in vestibular neuritis: a pilot study of concordance/discordance between ocular vestibular evoked myogenic potentials and ocular cycloposition

[Practical instructions for recording vestibular evoked myogenic potentials]

Recording of vestibular evoked myogenic potentials (VEMPs) is a well-established method for functional diagnostics of the otolith organs. VEMPs are vestibular reflexes of the sacculus und utriculus to acoustic stimulation by air-conducted sound or bone-conducted vibration and are recorded by surface electrodes from the cervical (cVEMP) and ocular (oVEMP) muscles. The results of VEMP recordings are part of the neuro-otologic test battery and enable diagnosis of various vestibular disorders or differentiation between non-vestibular and peripheral vestibular vertigo. However, the methods for recording VEMPs vary substantially, although recording and stimulation parameters as well as methods of data analysis have a significant influence on the results. This article provides an overview of recommended parameters as well as practical instructions for the recording, analysis, and interpretation of VEMPs.

The Relationship between the Subjective Visual Horizontal and Ocular Vestibular Evoked Myogenic Potentials in Acute Vestibular Neuritis

OBJECT

Vestibular evoked myogenic potentials (VEMPs) and the subjective visual horizontal (SVH) (or vertical [SVV]) have both been considered tests of otolith function: ocular-VEMPs (oVEMPs) utricular function, cervical VEMPs (cVEMPs) saccular function. Some studies have reported association between decreased oVEMPs and SVH, whereas others have not.

DESIGN

A retrospective study of test results.

SETTING

A tertiary, neuro-otology clinic, Royal Prince Alfred Hospital, Sydney, Australia.

METHOD

We analyzed results in 130 patients with acute vestibular neuritis tested within 5 days of onset. We sought correlations between the SVH, oVEMPs, and cVEMPs to air-conducted (AC) and bone-conducted (BC) stimulation.

RESULTS

The SVH deviated to the side of lesion, in 123 of the 130 AVN patients, by 2.5 to 26.7 degrees. Ninety of the AVN patients (70%) had abnormal oVEMPs to AC, BC or both stimuli, on the AVN side (mean asymmetry ratio ± SD [SE]): (64 ± 45.0% [3.9]). Forty-three of the patients (35%) had impaired cVEMPs to AC, BC or both stimuli, on the AVN side, [22 ± 41.6% (4.1)]. The 90 patients with abnormal oVEMP values also had abnormal SVH. Correlations revealed a significant relationship between SVH offset and oVEMP asymmetry (r = 0.80, p < 0.001) and a weaker relationship between SVH offset and cVEMP asymmetry (r = 0.56, p < 0.001).

CONCLUSIONS

These results indicate that after an acute unilateral vestibular lesion, before there has been a chance for vestibular compensation to occur, there is a significant correlation between the SVH, and oVEMP results. The relationship between SVH offset and oVEMP amplitude suggests that both tests measure utricular function.

Subjective visual horizontal correlates better with ocular than with cervical vestibular evoked myogenic potentials

OBJECTIVE

To examine the relationship between widely used otolith function tests: the Subjective Visual Horizontal (SVH) and Vestibular Evoked Myogenic Potentials (VEMP).

METHODS

A retrospective analysis was performed on 301 patients who underwent SVH, ocular and cervical VEMP (oVEMP and cVEMP) tests on the same day. Correlations between the mean SVH tilt and amplitude asymmetry ratios for bone-conducted (BC) oVEMP and air-conducted (AC) cVEMP were examined. Diagnoses included vestibular neuritis, stroke, vestibular migraine, Meniere's disease, sudden sensorineural hearing loss (SSNHL) and vestibular schwannoma.

RESULTS

SVH results were concordant with the oVEMP in 64% of cases and the cVEMP in 51%. Across all patients, SVH demonstrated a significant moderate correlation with BC oVEMP amplitude asymmetry ratios (r = 0.55, p < 0.001) and a weak correlation with AC cVEMP amplitude asymmetry ratios (r = 0.35, p < 0.001). A stronger correlation between SVH and oVEMPs was observed in patients with vestibular neuritis (r = 0.67, p < 0.001) and SSNHL (r = 0.76, p = 0.001).

CONCLUSIONS

SVH correlates better with oVEMP than cVEMP symmetry.

SIGNIFICANCE

This finding reinforces the hypothesis of a common utricular origin for both SVH and oVEMPs which is distinct from the saccular origin of cVEMPs.

Deep Learning Model for Static Ocular Torsion Detection Using Synthetically Generated Fundus Images

Purpose

The objective of the study is to develop deep learning models using synthetic fundus images to assess the direction (intorsion versus extorsion) and amount (physiologic versus pathologic) of static ocular torsion. Static ocular torsion assessment is an important clinical tool for classifying vertical ocular misalignment; however, current methods are time-intensive with steep learning curves for frontline providers.

Methods

We used a dataset (n = 276) of right eye fundus images. The disc-foveal angle was calculated using ImageJ to generate synthetic images via image rotation. Using synthetic datasets (n = 12,740 images per model) and transfer learning (the reuse of a pretrained deep learning model on a new task), we developed a binary classifier (intorsion versus extorsion) and a multiclass classifier (physiologic versus pathologic intorsion and extorsion). Model performance was evaluated on unseen synthetic and nonsynthetic data.

Results

On the synthetic dataset, the binary classifier had an accuracy and area under the receiver operating characteristic curve (AUROC) of 0.92 and 0.98, respectively, whereas the multiclass classifier had an accuracy and AUROC of 0.77 and 0.94, respectively. The binary classifier generalized well on the nonsynthetic data (accuracy = 0.94; AUROC = 1.00).

Conclusions

The direction of static ocular torsion can be detected from synthetic fundus images using deep learning methods, which is key to differentiate between vestibular misalignment (skew deviation) and ocular muscle misalignment (superior oblique palsies).

Translational Relevance

Given the robust performance of our models on real fundus images, similar strategies can be adopted for deep learning research in rare neuro-ophthalmologic diseases with limited datasets.

Vestibular function testing in the 21st century: video head impulse test, vestibular evoked myogenic potential, video nystagmography; which tests will provide answers?

PURPOSE OF REVIEW

To most neurologists, assessing the patient with vertigo is an unpleasant and worrisome task. A structured history and focused examination can be complemented by carefully selected laboratory tests, to reach an early and accurate diagnosis. We provide evidence-based recommendations for vestibular test selection.

RECENT FINDINGS

The video head impulse test (vHIT), cervical and ocular vestibular evoked myogenic potential (VEMP) and home-video nystagmography are four modern, noninvasive methods of assessing vestibular function, which are equally applicable in the hospital and office-practice. Collectively, they enable assessment of all five vestibular end-organs. The prevalence and patterns of test abnormalities are distinct for each vestibular disorder. We summarize typical abnormalities encountered in four common vestibular syndromes.

SUMMARY

In the context of acute vestibular syndrome, an abnormal vHIT with low gain and large amplitude refixation saccades and an asymmetric oVEMP separates innocuous vestibular neuritis from stroke. In episodic spontaneous vertigo, high-velocity ictal nystagmus and asymmetric cVEMP help separate Ménière's disease from vestibular migraine. In chronic imbalance, all three tests help detect unilateral or bilateral vestibular loss as the root cause. Recurrent positional vertigo requires no laboratory test and can be diagnosed and treated at the bedside, guided by video nystagmography.

Evaluation of the Video Ocular Counter-Roll (vOCR) as a New Clinical Test of Otolith Function in Peripheral Vestibulopathy

Importance

Video-oculography (VOG) goggles have been integrated into the assessment of semicircular canal function in patients with vestibular disorders. However, a similar bedside VOG method for testing otolith function is lacking.

Objective

To evaluate the use of VOG-based measurement of ocular counter-roll (vOCR) as a clinical test of otolith function.

Design, Setting, and Participants

A case-control study was conducted to compare vOCR measurement among patients at various stages of unilateral loss of vestibular function with healthy controls. The receiver operating characteristic curve method was used to determine the diagnostic accuracy of the vOCR test in detecting loss of otolith function. Participants were recruited at a tertiary center including the Johns Hopkins outpatient clinic and Johns Hopkins Hospital, Baltimore, Maryland. Participants included 56 individuals with acute (≤4 weeks after surgery), subacute (4 weeks-6 months after surgery), and chronic (>6 months after surgery) unilateral vestibular loss as well as healthy controls. A simple bedside maneuver with en bloc, 30° lateral tilt of the head and trunk was used for vOCR measurement. The study was conducted from February 2, 2017, to March 10, 2019.

Intervention

In each participant vOCR was measured during static tilts of the head and trunk en bloc.

Main Outcomes and Measures

The vOCR measurements and diagnostic accuracy of vOCR in detecting patients with loss of vestibular function from healthy controls.

Results

Of the 56 participants, 28 (50.0%) were men; mean (SD) age was 53.5 (11.4) years. The mean (SD) time of acute unilateral vestibular loss was 9 (7) days (range, 2-17 days) in the acute group, 61 (39) days (range, 28-172 days) in the subacute group, and 985 (1066) days (range 185-4200 days) in the chronic group. The vOCR test showed reduction on the side of vestibular loss, and the deficit was greater in patients with acute and subacute vestibular loss than in patients with chronic loss and healthy controls (acute vs chronic: -1.81°; 95% CI, -3.45° to -0.17°; acute vs control: -3.18°; 95% CI, -4.83° to -1.54°; subacute vs chronic: -0.63°; 95% CI, -2.28° to 1.01°; subacute vs control: -2.01°; 95% CI, -3.65° to -0.36°; acute vs subacute: -1.17°; 95% CI, -2.88° to 0.52°; and chronic vs control: -1.37°; 95% CI, -2.96° to 0.21°). The asymmetry in vOCR between the side of vestibular loss and healthy side was significantly higher in patients with acute vs chronic loss (0.28; 95% CI, 0.06-0.51). Overall, the performance of the vOCR test in discriminating between patients with vestibular loss and healthy controls was 0.83 (area under the receiver operating characteristic curve). The best vOCR threshold to detect vestibular loss at the 30° tilt was 4.5°, with a sensitivity of 80% (95% CI, 0.62%-0.88%) and specificity of 82% (95% CI, 0.57%-1.00%).

Conclusions and Relevance

The findings of this case-control study suggest that the vOCR test can be performed with a simple bedside maneuver and may be used to detect or track loss of otolith function.

Cochlear implant surgery and perioperative dizziness is associated with utricular hyperfunction

BACKGROUND

Dizziness is a common perioperative complication after cochlear implantation (CI). To date, the exact cause behind this phenomenon remains unclear. There is recent evidence to suggest that otolith function, specifically utricular, may be affected shortly after CI surgery, however whether these changes are related to patient symptoms has not yet been investigated.

OBJECTIVE

To determine whether CI surgery and perioperative dizziness is associated with changes on utricular function.

METHODS

We performed an observational study on patients undergoing routine CI surgery. Utricular function was assessed using the Subjective Visual Vertical (SVV), and perioperative dizziness was determined using a questionnaire. The study followed patients before surgery and then again 1-day, 1-week and 6-weeks after implantation.

RESULTS

Forty-one adult CI recipients participated in the study. The SVV deviated away from the operated ear by an average of 2.17° a day after implantation, 0.889° 1 week and -0.25° 6 weeks after surgery. Dizziness contributed to a tilt of 0.5° away from the implanted ear. These deviations were statistically significant.

CONCLUSIONS

CI surgery causes utricular hyperfunction in the operated ear that resolves over 6 weeks. SVV tilts were greater in participants experiencing dizziness, suggesting that utricular hyperfunction may contribute to the dizziness.

Different time course of compensation of subjective visual vertical and ocular torsion after acute unilateral vestibular lesion

PURPOSE

Time course of the recovery of otolithic dis-function caused by superior vestibular neuritis has been examined in fifteen patients.

METHODS

The subjective visual vertical (SVV) and the ocular cyclotorsion (OT) have been measured four times after the acute episode up to 1 year RESULTS: In most of the patients the SVV tilt returned to control values within few months (3-6 months) after the acute episode, while OT remained out of normal range in almost all patients a year later.

CONCLUSION

The abnormal OT observed after 1 year from the acute episode of vestibular neuritis, suggests that the otolithic receptors remained altered for several months and the OT may be a good indicator of the entity of the residual peripheral otolithic lesion. Moreover, the dissociation between the SVV tilt recovery and that of OT supports the issue that the two signs of the otolithic disfunction are only partially linked each other with centrally or peripherally distinct re-balancing circuits.

Independent Measures of Utricular Function: Ocular Vestibular Evoked Myogenic Potentials Do Not Correlate With Subjective Visual Vertical or Fundus Photographic Binocular Cyclorotation

Ocular vestibular evoked myogenic potentials (oVEMPs), subjective visual vertical (SVV), and fundus photographically measured binocular cyclorotation (BCR) are diagnostic tests to assess utricular function in patients with vertigo or dizziness. In 138 patients with chronic vertigo or dizziness, we asked whether the asymmetry ratio of oVEMP (normal, right side pathological, left side pathological) could predict the SVV deviation (normal, rightward deviation, leftward deviation) or BCR (normal, cyclorotation to the right, cyclorotation to the left). There was no correlation between oVEMP and SVV and between oVEMP and BCR, while SVV and BCR correlated highly. Although both oVEMP and SVV measure aspects of utricular function, our findings demonstrate that oVEMP and SVV are not redundant and may reflect different utricular pathologies. The role of fundus photographic BCR may be relegated to only confirm unclear SVV results in vestibular diagnostic workup.

Static and dynamic otolith reflex function in people with Parkinson's disease

PURPOSE

Parkinson's disease (PD) is a neurodegenerative disorder with possible vestibular system dysfunction. This study reports the transient and sustained functions of the otoliths and their reflex pathways in PD compared to healthy controls (HC) and determines if otolith function relates to previous fall history.

METHODS

Forty participants with PD and 40 HC had their otolith function assessed. Transient saccular and utricular-mediated reflexes were assessed by cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs, respectively) elicited by air-conducted stimulus (clicks) and bone-conducted vibration (light tendon hammer taps). Static otolith function was assessed by the Curator Subjective Visual Vertical (SVV) test.

RESULTS

Compared to HC, the PD group had significantly more absent cVEMP responses to both clicks (47.5% vs. 30%, respectively, p = 0.03) and taps (21.8% vs. 5%, respectively, p = 0.002). Only the PD group had bilaterally absent tap cVEMPs, this was related to previous falls history (p < 0. 001). In both groups, click oVEMPs were predominantly absent, and tap oVEMPs were predominantly present. The PD group had smaller tap oVEMP amplitudes (p = 0.03) and recorded more abnormal SVV responses (p = 0.01) and greater error on SVV compared to HC, p < 0.001. SVV had no relationship with VEMP responses (p = 0.14).

CONCLUSIONS

PD impacts on cVEMP reflex pathways but not tap oVEMP reflex pathways. Bone-conducted otolith stimuli (taps) are more robust than air-conducted sound stimuli (clicks) for both o and cVEMPs. A lack of association between SVV and VEMP responses suggest that static and dynamic otolith functions are differentially affected in PD.

The Anatomical and Physiological Basis of Clinical Tests of Otolith Function. A Tribute to Yoshio Uchino

Otolithic receptors are stimulated by gravitoinertial force (GIF) acting on the otoconia resulting in deflections of the hair bundles of otolithic receptor hair cells. The GIF is the sum of gravitational force and the inertial force due to linear acceleration. The usual clinical and experimental tests of otolith function have used GIFs (roll tilts re gravity or linear accelerations) as test stimuli. However, the opposite polarization of receptors across each otolithic macula is puzzling since a GIF directed across the otolith macula will excite receptors on one side of the line of polarity reversal (LPR at the striola) and simultaneously act to silence receptors on the opposite side of the LPR. It would seem the two neural signals from the one otolith macula should cancel. In fact, Uchino showed that instead of canceling, the simultaneous stimulation of the oppositely polarized hair cells enhances the otolithic response to GIF—both in the saccular macula and the utricular macula. For the utricular system there is also commissural inhibitory interaction between the utricular maculae in each ear. The results are that the one GIF stimulus will cause direct excitation of utricular receptors in the activated sector in one ear as well as indirect excitation resulting from the disfacilitation of utricular receptors in the corresponding sector on the opposite labyrinth. There are effectively two complementary parallel otolithic afferent systems—the sustained system concerned with signaling low frequency GIF stimuli such as roll head tilts and the transient system which is activated by sound and vibration. Clinical tests of the sustained otolith system—such as ocular counterrolling to roll-tilt or tests using linear translation—do not show unilateral otolithic loss reliably, whereas tests of transient otolith function [vestibular evoked myogenic potentials (VEMPs) to brief sound and vibration stimuli] do show unilateral otolithic loss. The opposing sectors of the maculae also explain the results of galvanic vestibular stimulation (GVS) where bilateral mastoid galvanic stimulation causes ocular torsion position similar to the otolithic response to GIF. However, GVS stimulates canal afferents as well as otolithic afferents so the eye movement response is complex.