The association of the plasma vasopressin level during attacks with a prognosis of Meniere's disease

Vestibular Disorders and Hormonal Dysregulations: State of the Art and Clinical Perspectives

The interaction between endocrine and vestibular systems remains poorly documented so far, despite numerous observations in humans and animals revealing direct links between the two systems. For example, dizziness or vestibular instabilities often accompany the menstrual cycle and are highly associated with the pre-menopause period, while sex hormones, together with their specific receptors, are expressed at key places of the vestibular sensory network. Similarly, other hormones may be associated with vestibular disorders either as causal/inductive factors or as correlates of the pathology. This review was carried out according to the PRISMA method, covering the last two decades and using the MEDLINE and COCHRANE databases in order to identify studies associating the terms vestibular system and/or vestibular pathologies and hormones. Our literature search identified 646 articles, 67 of which referred directly to vestibular dysfunction associated with hormonal variations. While we noted specific hormonal profiles depending on the pathology considered, very few clinical studies attempted to establish a direct link between the expression of the vestibular syndrome and the level of circulating hormones. This review also proposes different approaches to shed new light on the link between hormones and vestibular disorders, and to improve both the diagnosis and the therapeutic management of dizzy patients.

Functional and Molecular Markers for Hearing Loss and Vertigo Attacks in Meniere's Disease

Meniere's disease (MD) is one of the most complicated diseases in the otologic clinic. The complexity of MD is partially due to the multifactorial etiological mechanisms and the heterogenous symptoms, including episodic vertigo, hearing loss, aural fullness and tinnitus. As a result, the diagnosis of MD and differentiating MD from other diseases with similar symptoms, such as vestibular migraine (VM), is challenging. In addition, it is difficult to predict the progression of hearing loss and the frequency of vertigo attacks. Detailed studies have revealed that functional markers, such as pure tone audiometry (PTA), electrocochleography (ECochG), vestibular evoked myogenic potential (VEMP), caloric test, video head impulse test (vHIT) and magnetic resonance imaging (MRI) could help to evaluate MD with different hearing levels and frequency of vertigo attacks. Investigations of molecular markers such as autoimmunity, inflammation, protein signatures, vasopressin and circadian clock genes in MD are still underway. This review will summarize these functional and molecular markers, address how these markers are associated with hearing loss and vertigo attacks in MD, and analyze the results of the markers between MD and VM.

Hormones and Vestibular Disorders: The Quest for Biomarkers

The vestibular system exerts control over various functions through neural pathways that are not yet fully mapped. Functional dysregulations or tissue lesions at different levels of the peripheral and the central vestibular networks can alter these different functions, causing a wide variety of symptoms, ranging from posturo-locomotor alterations to psychiatric syndromes such as PPPD, including the deregulation of the main biological functions. These different symptoms differ by their expression kinetics (they each appear and regress with their own kinetics) by the targets affected (muscles, organs, and brain areas) and by the sensitivity specific to each individual. Vestibular pathologies thus cover a mosaic of distinct effects, and they involve various effectors—which constitute the many markers of their different types and stages. It is therefore crucial, to predict the onset of a vertigo syndrome, to follow its temporal course, or to monitor the impact of therapeutic approaches, and to have specific and reliable biomarkers. Hormonal variations are among the possible sources of biomarkers for neurotology. We know that specific hormonal profiles can promote the appearance of vestibular disorders. We also know that the expression of vertigo syndrome is accompanied by measurable hormonal variations. The link between endocrine deregulation and vestibular alterations therefore no longer needs to be proven. However, there are still few data on their precise correlations with the vertigo syndrome. This study was undertaken with the aim to deliver an extensive review of the hormonal alterations linked to vestibular disorders. A review of the literature covering the last two decades was carried out using the MEDLINE and COCHRANE databases in order to identify studies associating the terms vestibular system or vestibular pathologies and hormones. Bibliographic data provides several outcomes in terms of therapeutic innovation in the diagnosis and therapeutic follow-up of vestibular pathologies.

Stress and Unusual Events Exacerbate Symptoms in Menière's Disease: A Longitudinal Study

HYPOTHESIS

Stress and unusual events are associated with a higher likelihood of attacks and increased symptom severity in Menière's disease (MD).

BACKGROUND

MD is an unpredictable condition which severely impacts the quality of life of those affected. It is thought that unusual activity and stress may act as an attack trigger in MD, but research in this area has been limited to date.

METHODS

This was a longitudinal study conducted over two phases. A mobile phone application was used to collect daily data on Menière's attacks and individual symptoms (aural fullness, dizziness, hearing loss, and tinnitus), as well as prevalence of unusual events (phase I), and stress levels (phase II). There were 1,031 participants (730 women, mean age 46.0 yr) in phase I and 695 participants (484 women, mean age 47.7 yr) in phase II. Panel data regression analyses were employed to examine for associations between unusual events/stress and attacks/symptoms, including the study of 24 hours lead and lag effects.

RESULTS

Unusual events and higher stress levels were associated with higher odds of Menière's attacks and more severe symptoms. The odds of experiencing an attack were 2.94 (95% confidence interval [CI] 2.37, 3.65) with reporting of unusual events and increased by 1.24 (95% CI 1.20, 1.28) per unit increase in stress level. Twenty-four hour lead (OR 1.10 [95% CI 1.07, 1.14]) and lag (OR 1.10 [95% CI 1.06, 1.13]) effects on attacks were also found with increases in stress.

CONCLUSION

This study provides the strongest evidence to date that stress and unusual events are associated with attacks and symptom exacerbation in MD. Improving our understanding of stress and unusual events as triggers in Menière's may reduce the uncertainty associated with this condition and lead to improved quality of life for affected individuals.

Vasopressin Proves Es-sense-tial: Vasopressin and the Modulation of Sensory Processing in Mammals

As mammals develop, they encounter increasing social complexity in the surrounding world. In order to survive, mammals must show appropriate behaviors toward their mates, offspring, and same-sex conspecifics. Although the behavioral effects of the neuropeptide arginine vasopressin (AVP) have been studied in a variety of social contexts, the effects of this neuropeptide on multimodal sensory processing have received less attention. AVP is widely distributed through sensory regions of the brain and has been demonstrated to modulate olfactory, auditory, gustatory, and visual processing. Here, we review the evidence linking AVP to the processing of social stimuli in sensory regions of the brain and explore how sensory processing can shape behavioral responses to these stimuli. In addition, we address the interplay between hormonal and neural AVP in regulating sensory processing of social cues. Because AVP pathways show plasticity during development, early life experiences may shape life-long processing of sensory information. Furthermore, disorders of social behavior such as autism and schizophrenia that have been linked with AVP also have been linked with dysfunctions in sensory processing. Together, these studies suggest that AVP's diversity of effects on social behavior across a variety of mammalian species may result from the effects of this neuropeptide on sensory processing.

Diuretics in Meniere disease: a therapy or a potential cause of harm?

Despite the lack of clear evidence for their effectiveness in treating vertigo, tinnitus, hearing loss and aural fullness, diuretics, represent a common treatment for Meniere disease (MD), as they are supposed to decrease volume and pressure in the endolymphatic partition of the labyrinth. Our group have outlined the possibility of an adverse effect on inner ear function derived from an abrupt lowering of blood pressure: a subsequent exaggerated vasomotor response inducing local ischemia could be responsible for more or less permanent damage. The inner ear, owing both to its terminal vascular supply and to the necessity of a steady metabolism, seems a reliable target for any hemodynamic imbalance that acutely affect its perfusion. In our opinion, the complexity of the inner ear anatomy and function argues against the usefulness of diuretics to reduce endolymphatic volume, in analogy to their effect on the volemia: too many active mechanisms and "buffer" systems are involved in the labyrinth. Even considering that the finding of mean low pressure values is relatively common in subjects with MD, an attempt should be to maintain a stable blood perfusion to the labyrinth; in fact, an abrupt decrease in systemic blood pressure can trigger an adverse sympathetic reaction and transmit misleading information to the cochlear vasopressin receptors.