COVID-19 and Vestibular Symptoms and Assessment: A Review.

BACKGROUND: The current pandemic of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in significant morbidity and mortality primarily associated with respiratory failure. However, it has also been reported that COVID-19 can evolve into a nervous system infection. The direct and indirect mechanisms of damage associated with SARS-CoV-2 neuropathogenesis could affect our sensory functionality, including hearing and balance. SUMMARY: In order to investigate a possible association between SARS-CoV-2 viral infection and possible damage to the vestibular system, this review describes the main findings related to diagnosing and evaluating otoneurological pathologies. KEY MESSAGES: The clinical evidence shows that SARS-CoV-2 causes acute damage to the vestibular system that would not leave significant sequelae. Recovery is similar to vestibular pathologies such as vestibular neuronitis and benign paroxysmal positional vertigo. Further basic science, clinical, and translational research is needed to verify and understand the short- and long-term effects of COVID-19 on vestibular function.

Assessment of functional and structural brain abnormalities with resting-state functional MRI in patients with vestibular neuronitis.

BACKGROUND: Vestibular neuritis (VN) is a disorder manifesting as acute, isolated, spontaneous vertigo. There are few comprehensive studies on the changes in related functional and structural brain regions. PURPOSE: To evaluate alterations in spontaneous neural activity, functional connectivity (FC), and gray matter volume (GMV) in patients with VN. MATERIAL AND METHODS: A total of 24 patients with VN and 22 age- and sex-matched healthy controls underwent resting-state functional magnetic resonance imaging (rs-fMRI) and three-dimensional T1-weighted anatomical imaging. We calculated the amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC) to discern local brain abnormalities. The most abnormal brain region was selected as the region of interest (ROI) for FC analysis based on ALFF and ReHo values after Bonferroni correction. Voxel-based morphometry (VBM) was used to assess differences in GMV. RESULTS: Patients with VN, compared to healthy controls, showed increased ALFF (P < 0.001), ReHo values (P = 0.002, <0.001), and DC (P = 0.013) in the left lingual gyrus and right postcentral gyrus. FC analysis demonstrated enhanced connectivity between the left lingual gyrus and the left superior frontal gyrus, and decreased connectivity with the right insula gyrus, right and left supramarginal gyrus (P = 0.012, 0.004, <0.001, 0.014). In addition, GMV was reduced in the bilateral caudate (P = 0.022, 0.014). CONCLUSIONS: Patients with VN exhibit abnormal spontaneous neural activity and changes in ALFF, ReHo, DC, GMV, and FC. Understanding these functional and structural brain abnormalities may elucidate the underlying mechanisms of VN.

VEMPs and Dysautonomia Assessment in Definite Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS): a Case Series Study.

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a recently described slowly progressive ataxia with severe imbalance due to the compromise of three of the four sensory inputs for balance, leaving only vision unaffected. Bilateral vestibulopathy is present but saccular and utricular function, measured by vestibular evoked myogenic potentials (VEMPs), has not been widely studied in these patients. Dysautonomia has been reported but is not among the diagnostic criteria. We performed a database analysis to identify patients evaluated between 2003 and 2019 with probable diagnosis of CANVAS by using key words "bilateral vestibulopathy and/or cerebellar ataxia and/or sensory polyneuropathy." Five out of 842 met all conditions. Patients underwent neurological/neurootological exam, brain MRI, visually enhanced vestibulo-ocular reflex (VVOR) exam by high-speed video-oculography using video-Head Impulse Test (vHIT), VEMPs, neurophysiological studies, and genetic tests to exclude other causes of ataxia. Dysautonomia was addressed by the standardized survey of autonomic symptoms. All patients had clinically definite CANVAS as brain MRI showed vermal cerebellar atrophy, neurophysiological studies showed a sensory neuronopathy pattern (absent sensory action potentials), VVOR was abnormal bilaterally, and genetic tests ruled out other causes of ataxia including SCA 3 and Friedreich ataxia. Patients had at least 3 dysautonomic symptoms, including xerostomia/xerophthalmia (5/5). VEMP results varied among patients, ranging from normal to completely abnormal. We found inconsistent results with VEMPs. The utilization of VEMPs in more CANVAS cases will determine its utility in this syndrome. Dysautonomia may be included in the diagnostic criteria.

The Price of Immune Responses and the Role of Vitamin D in the Inner Ear.

OBJECTIVE: In this review the authors discuss evidence from the literature concerning vitamin D and temporal bone diseases (benign paroxysmal positional vertigo [BPPV], Menière's disease [MD], vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss). Common features shared by Menière's disease, glaucoma, and the possible influence by vitamin D are briefly discussed. DATA SOURCES, STUDY SELECTION: Publications from 1970 until recent times have been reviewed according to a keyword search (see above) in PubMed. CONCLUSIONS: MD, BPPV, vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss may all have several etiological factors, but a common feature of the current theories is that an initial viral infection and a subsequent autoimmune/autoinflammatory reaction might be involved. Additionally, in some of these entities varying degrees of demyelination have been documented. Given the immunomodulatory effect of vitamin D, we postulate that it may play a role in suppressing an eventual postviral autoimmune reaction. This beneficial effect may be enhanced by the antioxidative activity of vitamin D and its potential in stabilizing endothelial cells. The association of vitamin D deficiency with demyelination has already been established in other entities such as multiple sclerosis and experimental autoimmune encephalitis. Mice without vitamin D receptor show degenerative features in inner ear ganglia, hair cells, as well as otoconia. The authors suggest further studies concerning the role of vitamin D deficiency in diseases of the temporal bone. Additionally, the possible presence and degree of demyelination in these entities will have to be elucidated more systematically in the future.

Assessment of Vestibulo-ocular Reflex Gain and Catch-up Saccades During Vestibular Rehabilitation.

OBJECTIVE: To assess, in patients referred to vestibular rehabilitation (VR) for persistence of disability after acute unilateral vestibulopathy (AUV), whether the video head impulse test (vHIT) can be a useful technique to define the efficacy of the treatment. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary academic referral hospitals. PATIENTS: Thirty patients with residual symptoms after AUV were included. INTERVENTION: Patients underwent a 10-week VR program. MAIN OUTCOME MEASURES: Evaluation of dizziness handicap inventory score, high-velocity vestibulo-ocular reflex gain, asymmetry index, and catch-up saccade parameters before and after VR. RESULTS: All patients reported a clear clinical improvement after VR, also demonstrated by better dizziness handicap inventory scores (p < 0.001). A consistent increased gain and decreased asymmetry index were also observed (p < 0.001 for both). Patients did not show any change in covert catch-up saccades, while a statistically significant reduction of the number and amplitude of the overt catch-up saccades was interestingly detected (p = 0.009 and p = 0.030, respectively). CONCLUSION: VR is a valid approach for patients with residual disability after AUV. A reduction in number and amplitude of overt catch-up saccades seems useful to evaluate the efficacy of VR and to be related to clinical improvement.

The takeaway Frenzel goggles: a Fresnel-based device.

OBJECTIVE: To develop and evaluate new thin and light glasses for the examination of patients with nystagmus and to compare them with Frenzel goggles. METHODS: First, we designed new examination glasses: a Fresnel-based device with a short focal length that is not as heavy or bulky as Frenzel goggles. Second, visual-fixation suppression of postrotatory nystagmus with Frenzel goggles and the Fresnel-based device, the latter with 2 different magnifications (2- and 4-fold), was compared in 13 healthy subjects. Third, the intensity of the peripheral vestibular spontaneous nystagmus-in 6 patients with acute vestibular neuritis-with the Frenzel goggles and the Fresnel-based device with the 4-fold magnification was compared. Fourth, the visibility and clinical applicability were evaluated. RESULTS: The Fresnel-based device weighs 6 g (dimensions 12 × 8 × 0.3 cm). There was no significant difference in the intensity of postrotatory nystagmus between the Fresnel-based device with 4-fold magnification (37.3 ± 17.9°/s) and the Frenzel goggles (39.0 ± 18.3°/s). There was also no significant difference between the intensity of peripheral vestibular spontaneous nystagmus in the patients with acute vestibular neuritis. The Fresnel-based device can be easily applied. CONCLUSION: For suppression of nystagmus, the new Fresnel-based device or so-called M glasses is not inferior to Frenzel goggles. Doctors can carry it in their pocket, it is inexpensive, and easy to handle and to fix to the patient's nose so that it can be used in daily practice for the bedside examination. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that, in subjects with nystagmus, a Fresnel-based device identifies a similar intensity of nystagmus as that identified by Frenzel goggles.

Reading while moving: the functional assessment of VOR.

The head impulse test (HIT) is nowadays recognized as the gold standard for clinical testing of the angular vestibulo-ocular reflex (VOR). By imposing unpredictable, abrupt head rotations in canal pairs' planes it aims at unveiling the dysfunction of the semicircular canal towards which the head is rotated based on Ewald's II law. Functional testing of the VOR aims at assessing the ability of the reflex to stabilize gaze in space and thus allow clear vision during head movements. The HIT device (HITD) approach exploits impulsive head rotations spawning a range of angular accelerations while requiring subjects to identify optotypes briefly displayed on a screen. Here we also recorded eye movements, so that the evaluation of the individual subject is based both on the VOR gain and on the percentage of correct answers with respect to a population of controls. Here we used the HITD to study 14 patients suffering from vestibular neuritis and 7 of those were re-tested after three months. We found that the HITD was able to unveil the ipsilesional deficit and the contralesional impairment, together with the improvement in the follow-up test.

Vestibular rehabilitation using the Nintendo® Wii Balance Board -- a user-friendly alternative for central nervous compensation.

CONCLUSION: The Nintendo® Wii Balance Board is a cost-effective and user-friendly alternative to other popular frequently used systems that aid vestibular compensation, particularly in elderly patients. In addition, further treatment in the home environment is possible. OBJECTIVE: This cohort study was designed to investigate the impact of the Nintendo® Wii Balance Board as a visual compensation device after acute vestibular neuritis. METHODS: Subjects were randomly assigned to one of two treatment groups. Group A (n = 37) performed customized exercises with the Nintendo® Wii Balance Board. Group B (n = 34) performed only two elected exercises as a control group for comparison of the results. Both groups underwent additive therapy with steroids (intravenous) in decreasing doses (250 mg decreasing to 25 mg over 10 days). The Sensory Organization Test (SOT), Dizziness Handicap Inventory (DHI), Vertigo Symptom Scale (VSS), and Tinneti questionnaire were evaluated immediately before treatment (baseline), at the end of treatment, i.e. at day 5, and after 10 weeks. RESULTS: The early use of a visual feedback system in the context of the balance training supports the central nervous vestibular compensation after peripheral labyrinthine disorders. Patients in group B (without training) required a longer in-patient stay (average 2.4 days, SD 0.4) compared with patients following early Wii rehabilitation. The absence of nystagmus under Frenzel's goggles in group A was observed 2.1 days (SD 0.5) earlier than in group B. Group A showed significantly better results in the SOT, DHI, VSS, and Tinneti questionnaire at all time points measured (p < 0.05).

Assessment of postural stability using foam posturography at the chronic stage after acute unilateral peripheral vestibular dysfunction.

OBJECTIVE: To investigate the utility of foam posturography for assessing equilibrium at the chronic stage after acute unilateral peripheral vestibulopathy. METHODS: Thirty-four consecutive patients (16 patients at the chronic stage) with acute unilateral peripheral vestibulopathy and absent caloric responses unilaterally were recruited, along with 66 healthy control subjects. Two-legged stance tasks were performed in 4 conditions: with eyes open or closed, with or without using foam rubber. We adopted 6 parameters: the movement velocity of the center of pressure, the envelopment area traced by the movement of the center of pressure with eyes closed/foam rubber, Romberg's ratios of velocity and area with foam rubber, and the foam ratios (the ratio of a parameter measured with and without foam rubber) of velocity and area with eyes closed. RESULTS: All 6 parameters were significantly higher in the patients in the acute/subacute stage (<3 mo) than in the control subjects (p < 0.0001). Five parameters, excluding the foam ratio of the area with eyes closed, were still significantly higher in the patients at the chronic stage (>3 mo) than in the control subjects (p < 0.01). CONCLUSION: Foam posturography is useful for assessing equilibrium even at the chronic stage after acute unilateral peripheral vestibulopathy.

Assessment of diagnostic accuracy of foam posturography for peripheral vestibular disorders: analysis of parameters related to visual and somatosensory dependence.

OBJECTIVES: Simple tests to detect peripheral vestibulopathy might be practically useful before conducting elaborate examinations. The purpose of this study was to assess the diagnostic accuracy of foam posturography for peripheral vestibulopathy, with emphasis on visual and somatosensory dependence. METHODS: Two-legged stance tasks were conducted in patients with unilateral (n=68) and bilateral (n=16) vestibulopathy and healthy controls (n=66), under four conditions; eyes open with and without the foam rubber, and eyes closed with and without the foam rubber. RESULTS: The values of six parameters; the velocity of movement of the center of pressure (COP) and envelopment area tracing by the movement of the COP in eyes closed/foam rubber, the Romberg's ratios of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber), of velocity and area in eyes closed, were significantly higher in unilateral and bilateral vestibulopathy compared with the control (p<0.001). The area under the receiver operating characteristic curve for the Romberg's ratio of velocity with the foam rubber was the largest. CONCLUSIONS: Foam posturography detected high levels of visual and somatosensory dependence in patients with vestibulopathy. SIGNIFICANCE: Foam posturography is useful for preliminary assessment of possible peripheral vestibulopathy.

Psychodynamic vulnerability factors in the development of panic disorders--a prospective trial in patients after vestibular neuritis.

BACKGROUND: In our 2-year prospective study of 80 patients admitted consecutively to our clinic with an episode of acute vestibular neuritis, a total of 8 patients later developed a panic disorder according to DSM-III-R criteria. The goal of our analysis was to determine whether certain conflict patterns (e.g. in the area of autonomy vs. dependence) or deficient psychological structure could predict later panic disorder, as might be expected based on psychodynamic theory. SAMPLING AND METHODS: Between 4 and 8 weeks after the acute vestibular episode, we evaluated all patients using operationalized psychodynamic diagnostics (OPD). With the different axes of the OPD system, we were able to assess patients' experience of illness (Axis I), potential conflicts (Axis III), and psychological structure (Axis IV) in a semiquantitative manner. RESULTS AND CONCLUSIONS: Poor psychosocial integration, a lack of social support, a high burden of suffering, and moderate to severe impairment of self-experience were able to account for 32.1% (Nagelkerkes R(2)=0.321) of variance in the development of panic disorder over the course of 2 years. However, contrary to what might have been expected based on psychodynamic theory, patients who later developed a panic disorder did not exhibit any differences in their Axis III or IV scores compared to patients who remained psychologically healthy.

Vertigo: clinical assessment and diagnosis.

Dizziness is a common presenting complaint to emergency departments and medical admission units; the key is to differentiate between central and peripheral causes of vertigo. This review focuses on bedside assessment of vertigo and, by looking at patterns of symptoms and signs, provides guidance as to when to suspect a central cause.

Effectiveness of careful bedside examination in assessment, diagnosis, and prognosis of vestibular neuritis.

OBJECTIVE: To determine whether the use of 4 bedside tests (head-impulse, head-heave, head-shake, and vibration tests) can be as effective as the caloric test, a widely accepted standard, in the diagnosis and prediction of the time to recovery from vestibular neuritis. DESIGN: Inception cohort (1-year follow-up), criterion standard study. SETTING: Primary referral center. PATIENTS: All patients had acute vertigo, and those having a diagnosis of vestibular neuritis were eligible for inclusion in the study. Sixty-eight patients (43 men and 25 women; mean age, 54.9 years) met this criterion, and 53 of them (77.9%) completed the study. MAIN OUTCOME MEASURES: Spontaneous head-shaking and vibration-induced nystagmus elicited with a battery-powered device were tested wearing Frenzel goggles. The head-impulse and head-heave tests were performed manually. Caloric irrigation was administered with hot, cold, and ice water. RESULTS: At baseline, more than half of the patients exhibited positive signs with all 4 tests and all had caloric paralysis or paresis. Signs with the head-impulse and head-heave tests correlated highly (odds ratio, 24.9; P < .001), as did those with the head-shake and vibration tests (odds ratio, 22.8; P < .001). Patients with a positive sign with the head-impulse or vibration test were 70% less likely to recover than were those with a negative sign. Head-impulse (hazard ratio, 0.08; P = .002) and head-shake (hazard ratio, 0.23; P = .01) test results were associated with the outcome of the caloric test. CONCLUSION: Careful bedside examination of patients with vestibular neuritis has both diagnostic value in the short term and prognostic value in the long term.

Production of diagnostic rules from a neurotologic database with decision trees.

A decision tree is an artificial intelligence program that is adaptive and is closely related to a neural network, but can handle missing or nondecisive data in decision-making. Data on patients with Meniere's disease, vestibular schwannoma, traumatic vertigo, sudden deafness, benign paroxysmal positional vertigo, and vestibular neuritis were retrieved from the database of the otoneurologic expert system ONE for the development and testing of the accuracy of decision trees in the diagnostic workup. Decision trees were constructed separately for each disease. The accuracies of the best decision trees were 94%, 95%, 99%, 99%, 100%, and 100% for the respective diseases. The most important questions concerned the presence of vertigo, hearing loss, and tinnitus; duration of vertigo; frequency of vertigo attacks; severity of rotational vertigo; onset and type of hearing loss; and occurrence of head injury in relation to the timing of onset of vertigo. Meniere's disease was the most difficult to classify correctly. The validity and structure of the decision trees are easily comprehended and can be used outside the expert system.

Decision tree induction in the diagnosis of otoneurological diseases.

Expert systems have been applied in medicine as diagnostic aids and education tools. The construction of a knowledge base for an expert system may be a difficult task; to automate this task several machine learning methods have been developed. These methods can be also used in the refinement of knowledge bases for removing inconsistencies and redundancies, and for simplifying decision rules. In this study, decision tree induction was employed to acquire diagnostic knowledge for otoneurological diseases and to extract relevant parameters from the database of an otoneurological expert system ONE. The records of patients with benign positional vertigo, Meniere's disease, sudden deafness, traumatic vertigo, vestibular neuritis and vestibular schwannoma were retrieved from the database of ONE, and for each disease, decision trees were constructed. The study shows that decision tree induction is a useful technique for acquiring diagnostic knowledge for otoneurological diseases and for extracting relevant parameters from a large set of parameters.