Evidence-based diagnostic use of VEMPs

BACKGROUND Vestibular evoked myogenic potentials (VEMPs) are increasingly being used for testing otolith organ function. OBJECTIVE This article provides an overview of the anatomical, biomechanical and neurophysiological principles underlying the evidence-based clinical application of ocular and cervical VEMPs (oVEMPs and cVEMPs). MATERIAL AND METHODS Systematic literature search in PubMed until April 2019. RESULTS Sound and vibration at a frequency of 500 Hz represent selective vestibular stimuli for the otolith organs. The predominant specificity of oVEMPs for contralateral utricular function and of cVEMPs for ipsilateral saccular function is defined by the different central projections of utricular and saccular afferents. VEMPs are particularly useful in the diagnosis of superior canal dehiscence and otolith organ specific vestibular dysfunction and as an alternative diagnostic approach in situations when video oculography is not possible or useful. CONCLUSION The use of VEMPs is a simple, safe, reliable and selective test of dynamic function of otolith organs

Physiology, clinical evidence and diagnostic relevance of sound-induced and vibration-induced vestibular stimulation

Purpose of review: To examine the recent literature concerning the neural basis and clinical evidence for the response of the labyrinth to sound and vibration: vestibular-evoked myogenic potentials (VEMPs) and vibration-induced nystagmus (VIN). Recent findings: There are two streams of information from each otolith - a sustained stream (afferents with regular resting activity, signalling gravity and low-frequency linear accelerations) and a transient stream (afferents with irregular resting activity) signalling onset of linear acceleration, and sound and vibration. These irregular neurons are synchronized to each cycle of the stimulus. Neurons in the transient stream are tested by presenting sounds or vibration (500 Hz) and using surface electrodes to measure myogenic potentials from muscles activated by otolithic stimuli (VEMPs). 100 Hz vibration activates irregular canal afferents and causes a stimulus-locked VIN in patients with asymmetric canal function. These new tests of the transient system have one big advantage over older tests of the sustained system - they reliably show the effect of long-term unilateral vestibular loss. Summary: The new physiological and anatomical evidence shows how sound and vibration activate otolith and canal receptors and so provides the scientific foundation for VEMPs and VIN, which are important tools for diagnosing vestibular disorders. VIDEO ABSTRACT: http://links.lww.com/CONR/A47

Corticosteroids in patients with vestibular neuritis: An updated meta‐analysis

Vestibular neuritis is a common neuro-otological entity. Therapeutically, corticosteroids are advised, although the evidence is limited. The objective of this review is to update meta-analyses of clinical trials that address the question of whether patients with vestibular neuritis treated with corticosteroids show better recovery than control patients. The electronic databases Medline, Scopus and Cochrane were searched for clinical trials for the years 1970-2020 without language restriction. Data were extracted, and outcome parameters were subjected to conventional and cumulative meta-analysis using a commercially available software program (www.meta-analysis.com). Finally, 15 trials with 363 participants in the treatment and 489 in the control groups were identified and could be included. Eight studies were judged to be at high risk of bias. The odds ratio (OR) for good outcome in the acute phase was 3.1 (95% CI 1.2-7.8; p = .015) in favour of steroid treatment leading to the number needed to treat (NNT) = 6 (95% CI 4-23). The odds ratio (OR) for restoration of vestibular function in the follow-up was 2.4 (95% CI 1.3-4.4; p = .004) for the benefit of steroid treatment resulting in a NNT = 7 (95% CI 5-18). The results of the cumulative statistics did not differ. The risk of adverse effects was higher in patients treated with steroids with an OR of 10.9 (95% CI 1.3-93.8; p = .015) and an estimated number needed to harm (NNH) = 4 (95% CI 3-19). The advantage for corticosteroids remained when differentiating between patients who participated in randomized or non-randomized clinical trials. Steroid treatment in vestibular neuritis resulted in a statistically significant benefit compared to control therapies. However, broad heterogeneity of the studies, mostly low-grade quality of studies, high risk of bias and broad confidence intervals put the findings into perspective allowing only a careful judgement of some benefit of corticosteroids. The findings, however, support the call for an adequately powered and well-designed randomized controlled trial to re-evaluate the effectiveness of corticosteroids

Acute Unilateral Peripheral Vestibulopathy After COVID-19 Vaccination: Initial Experience in a Tertiary Neurotology Center

ObjectiveThe aim of the present study was to identify patients who developed acute unilateral peripheral vestibulopathy (AUPVP) after COVID-19 vaccination.MethodsFor this single-center, retrospective study, we screened the medical records of our tertiary interdisciplinary neurotology center for patients who had presented with AUPVP within 30 days after COVID-19 vaccination (study period: 1 June−31 December 2021). The initial diagnosis of AUPVP was based on a comprehensive bedside neurotological examination. Laboratory vestibular testing (video head impulse test, cervical and ocular vestibular evoked myogenic potentials, dynamic visual acuity, subjective visual vertical, video-oculography, caloric testing) was performed 1–5 months later.ResultsTwenty-six patients were diagnosed with AUPVP within the study period. Of those, n = 8 (31%) had developed acute vestibular symptoms within 30 days after COVID-19 vaccination (mean interval: 11.9 days, SD: 4.8, range: 6–20) and were thus included in the study. The mean age of the patients (two females, six males) was 46 years (SD: 11.7). Seven patients had received the Moderna mRNA vaccine and one the Pfizer/BioNTech mRNA vaccine. All patients displayed a horizontal(-torsional) spontaneous nystagmus toward the unaffected ear and a pathological clinical head impulse test toward the affected ear on initial clinical examination. Receptor-specific laboratory vestibular testing performed 1–5 months later revealed recovery of vestibular function in two patients, and heterogeneous lesion patterns of vestibular endorgans in the remaining six patients.Discussion and ConclusionsThe present study should raise clinicians' awareness for AUPVP after COVID-19 vaccination. The relatively high fraction of such cases among our AUPVP patients may be due to a certain selection bias at a tertiary neurotology center. Patients presenting with acute vestibular symptoms should be questioned about their vaccination status and the date of the last vaccination dose. Furthermore, cases of AUPVP occurring shortly after a COVID-19 vaccination should be reported to the health authorities to help determining a possible causal relationship

A Review of Neural Data and Modelling to Explain How a Semicircular Canal Dehiscence (SCD) Causes Enhanced VEMPs, Skull Vibration Induced Nystagmus (SVIN), and the Tullio Phenomenon

Angular acceleration stimulation of a semicircular canal causes an increased firing rate in primary canal afferent neurons that result in nystagmus in healthy adult animals. However, increased firing rate in canal afferent neurons can also be caused by sound or vibration in patients after a semicircular canal dehiscence, and so these unusual stimuli will also cause nystagmus. The recent data and model by Iversen and Rabbitt show that sound or vibration may increase firing rate either by neural activation locked to the individual cycles of the stimulus or by slow changes in firing rate due to fluid pumping (“acoustic streaming”), which causes cupula deflection. Both mechanisms will act to increase the primary afferent firing rate and so trigger nystagmus. The primary afferent data in guinea pigs indicate that in some situations, these two mechanisms may oppose each other. This review has shown how these three clinical phenomena—skull vibration-induced nystagmus, enhanced vestibular evoked myogenic potentials, and the Tullio phenomenon—have a common tie: they are caused by the new response of semicircular canal afferent neurons to sound and vibration after a semicircular canal dehiscence

Early disruption of photoreceptor cell architecture and loss of vision in a humanized pig model of usher syndromes

Usher syndrome (USH) is the most common form of monogenic deaf-blindness. Loss of vision is untreatable and there are no suitable animal models for testing therapeutic strategies of the ocular constituent of USH, so far. By introducing a human mutation into the harmonin-encoding USH1C gene in pigs, we generated the first translational animal model for USH type 1 with characteristic hearing defect, vestibular dysfunction, and visual impairment. Changes in photoreceptor architecture, quantitative motion analysis, and electroretinography were characteristics of the reduced retinal virtue in USH1C pigs. Fibroblasts from USH1C pigs or USH1C patients showed significantly elongated primary cilia, confirming USH as a true and general ciliopathy. Primary cells also proved their capacity for assessing the therapeutic potential of CRISPR/Cas-mediated gene repair or gene therapy in vitro. AAV-based delivery of harmonin into the eye of USH1C pigs indicated therapeutic efficacy in vivo

Der „schwierige“ Patient – Vestibularisdiagnostik unter erschwerten Bedingungen : Teil 1: Anamnese und klinisch-neurootologische Untersuchung

Der Patient mit dem Leitsymptom Schwindel stellt häufig eine Herausforderung für den Hals-Nasen-Ohren-Arzt dar. Die folgende Artikelserie beleuchtet unterschiedliche Aspekte des „schwierigen“ Schwindelpatienten. Der vorliegende erste Teil widmet sich den Besonderheiten und Fallstricken bei der Anamneseerhebung und der klinisch-neurootologischen Untersuchung. Dabei werden situationsspezifische Lösungsansätze zu folgenden Themen der Anamneseerhebung aufgezeigt: Definition von Erwartungen und Zielen, „ausschweifende“ Anamnese, Beschreibung des Symptoms Schwindel, mehrere Schwindelentitäten bei einem Patienten, Diskrepanz zwischen Symptomschwere und vestibulären Befunden, kognitive Verzerrungen und der Umgang mit Emotionen. Des Weiteren werden praxisbezogene Hinweise für die neurootologische Untersuchung von Patienten mit Halswirbelsäulenproblemen und Augenbewegungsstörungen sowie bei ängstlichen Patienten gegeben. = Patients presenting with vertigo or dizziness may pose a real challenge for the clinical otorhinolaryngologist. This series of articles covers different aspects of the “difficult” dizzy patient. The first part is dedicated to pearls and pitfalls in history taking and clinical neurotological examination. It suggests possible solutions for challenging situations in history taking, such as definition of the expectations and aims, patients presenting with a long-winded history, patients’ description of the symptom “vertigo”, multiple vestibular syndromes in one patient, discrepancy between subjective symptoms and objective vestibular findings, cognitive bias and dealing with emotions. Furthermore, it offers practically oriented tips for the neurotological examination of patients with problems of the cervical spine, oculomotor disorders and anxiety.

Seltene Erkrankungen des vestibulären Labyrinths: von Zebras, Chamäleons und Wölfen im Schafspelz

Die Differenzialdiagnose von Erkrankungen des vestibulären Labyrinths stellt eine grosse Herausforderung dar, da sich hinter dem sehr häufigen Leitsymptom «Schwindel» viele verschiedene und v. a. seltene Erkrankungen verbergen können. Der vorliegende Beitrag gibt einen Überblick über die für den HNO-Arzt wichtigen seltenen Erkrankungen des vestibulären Labyrinths ausgehend von ihrer klinischen Präsentation als akutes (AVS), episodisches (EVS) oder chronisches vestibuläres Syndrom (CVS). Der Schwerpunkt liegt dabei auf den EVS, sortiert nach ihrer Dauer und dem Vorhandensein von Triggern (Sekunden, ohne Trigger: Vestibularisparoxysmie, Tumarkin-Krise; Sekunden, lärm- und druckinduziert: Syndrome des «dritten Fensters»; Sekunden bis Minuten, positionsabhängig: seltene Varianten und Differenzialdiagnosen des benignen paroxysmalen Lagerungsschwindels; Stunden bis Tage, spontan: intralabyrinthäre Schwannome, Tumoren des endolymphatischen Sacks, Autoimmunerkrankungen des Innenohres). Des Weiteren werden seltene Differenzialdiagnosen eines AVS (Neuritis vestibularis inf., Otolithenfunktionsstörungen, vaskuläre Ursachen, akute bilaterale Vestibulopathie) und eines CVS (bilaterale Vestibulopathie) erläutert. Dabei werden insbesondere die entscheidenden diagnostischen Massnahmen für die Identifikation der einzelnen Krankheitsbilder und die Warnzeichen für potentiell gefährliche Ursachen (z. B. Labyrinthinfarkt/-blutung) dargelegt. Somit dient dieser Beitrag dem HNO-Arzt in Klinik und Praxis als eine Art «Vademecum» für die zügige Identifikation und zeitnahe Therapie seltener Erkrankungen des Gleichgewichtsorgans. = The differential diagnosis of vertigo syndromes is a challenging issue, as many – and in particular – rare disorders of the vestibular labyrinth can hide behind the very common symptoms of “vertigo” and “dizziness”. The following article presents an overview of those rare disorders of the balance organ that are of special interest for the otorhinolaryngologist dealing with vertigo disorders. For a better orientation, these disorders are categorized as acute (AVS), episodic (EVS) and chronic vestibular syndromes (CVS) according to their clinical presentation. The main focus lies on EVS sorted by their duration and the presence/absence of triggering factors (seconds, no triggers: vestibular paroxysmia, Tumarkin attacks; seconds, sound and pressure induced: “third window” syndromes; seconds to minutes, positional: rare variants and differential diagnoses of benign paroxysmal positional vertigo; hours to days, spontaneous: intralabyrinthine schwannomas, endolymphatic sac tumors, autoimmune disorders of the inner ear). Furthermore, rare causes of AVS (inferior vestibular neuritis, otolith organ specific dysfunction, vascular labyrinthine disorders, acute bilateral vestibulopathy) and CVS (chronic bilateral vestibulopathy) are covered. In each case, special emphasis is laid on the decisive diagnostic test for the identification of the rare disease and “red flags” for potentially dangerous disorders (e. g. labyrinthine infarction/hemorrhage). Thus, this chapter may serve as a clinical companion for the otorhinolaryngologist aiding in the efficient diagnosis and treatment of rare disorders of the vestibular labyrinth