Subjective visual vertical/horizontal and video head impulse test in dyslexic children

Different studies have tried to establish a relationship between dyslexia and the vestibular system function. Subjective Visual Vertical/Horizontal (SVV and SVH) and Video Head Impulse Test (VHIT) are useful for studying the vestibular system and can be easily performed in children. Our aim was to evaluate the vestibular function in dyslexic children by SVV/SVH and VHIT. We enrolled 18 dyslexic children (10M/8F; mean age 10.7 ± 2.3 years; range 7-14 years) and 18 age-matched children with typical development of learning abilities. All children performed VHIT, SVV and SVH. We found normal gain and symmetry of vestibulo-ocular-reflex both in dyslexic and typically developing children. Fifteen out of 18 dyslexic children (83.3%) showed a difference of at least one amongst SVV or SVH. The mean value of SVV was 2.3° and the mean value of SVH was 2.6°. Statistical analysis showed a significant difference between typically developing and dyslexic children for both SVV and SVH. We confirm a relationship between dyslexia and the alteration of SVV and SVH. Our results could be related to the pathogenetic hypothesis of a visual processing impairment related to a dysfunction of the magnocellular pathway or to a general deficit related to a multimodal cortical network.

The Critical Thing about the Ear's Sensory Hair Cells

The capabilities of the human ear are remarkable. We can normally detect acoustic stimuli down to a threshold sound-pressure level of 0 dB (decibels) at the entrance to the external ear, which elicits eardrum vibrations in the picometer range. From this threshold up to the onset of pain, 120 dB, our ears can encompass sounds that differ in power by a trillionfold. The comprehension of speech and enjoyment of music result from our ability to distinguish between tones that differ in frequency by only 0.2%. All these capabilities vanish upon damage to the ear's receptors, the mechanoreceptive sensory hair cells. Each cochlea, the auditory organ of the inner ear, contains some 16,000 such cells that are frequency-tuned between ∼20 Hz (cycles per second) and 20,000 Hz. Remarkably enough, hair cells do not simply capture sound energy: they can also exhibit an active process whereby sound signals are amplified, tuned, and scaled. This article describes the active process in detail and offers evidence that its striking features emerge from the operation of hair cells on the brink of an oscillatory instability-one example of the critical phenomena that are widespread in physics.

A 5-week centrifuge-based G training with feedback on the magnitude of G force, does not improve the perception of roll tilt during simulated coordinated turns

When entering a coordinated flight turn without visual references, the perception of roll-angular displacement is determined by vestibular cues, and/or probably by assessment of the G load (G magnitude) and its translation into the corresponding bank angle. Herein, we examined whether repeated exposures to hypergravity (G training) in a centrifuge, would advance, not only the ability to accurately assess the G load, but also the capacity to detect or estimate the corresponding roll inclination of the centrifuge gondola. To this end, in 9 men without piloting experience, the subjective estimation of G load and roll tilt were assessed, in complete darkness, during 5-min coordinated turns in the centrifuge, performed at 1.1G (25° roll-tilt angle) and 2.0G (60° roll tilt angle). These trials were conducted before and after 5-weeks of G training [3×40-min sessions･week-1; protocol: 20×1-min at G levels close to the individual relaxed G-level tolerance (range: ∼2.6G(~67°)-3.6G(74°)), separated by 1-min intervals at idle speed (1.4G)], while continual feedback to the subjects was limited to the G load. As expected, G training improved subjects' capacity to assess G load, especially at 2.0 G (P=0.006). The perception of roll tilt, however, was consistently underestimated (by ~70-80%), and not enhanced by G training (P≥0.51). The present findings demonstrate that prolonged repeated G-induced roll-tilts in a centrifuge gondola, while external feedback is restricted to graviception, enhance the capacity to perceive G load, but fail to advance the ability to detect or consciously estimate the magnitude of roll-angular displacement during a coordinated turn.

Central tendency and serial dependence in vestibular path integration

Path integration, the process of updating one's position using successive self-motion signals, has previously been studied using visual distance reproduction tasks in which optic flow patterns provide information about traveled distance. These studies have reported that reproduced distances show two types of systematic biases: central tendency and serial dependence. In the present study, we investigated whether these biases are also present in vestibular path integration. Participants were seated on a linear motion platform and performed a distance reproduction task in total darkness. The platform first passively moved the participant a pre-defined stimulus distance which they then actively reproduced by steering the platform back the same distance. Stimulus distances were sampled from short- and long-distance probability distributions and presented in either a randomized order or in separate blocks to study the effect of presentation context. Similar to the effects observed in visual path integration, we found that reproduced distances showed an overall positive central tendency effect as well as a positive, attractive serial dependence effect. Furthermore, reproduction behavior was affected by presentation context. These results were mostly consistent with predictions of a Bayesian Kalman-filter model, originally proposed for visual path integration.

Causal association between blood metabolites and vertigo: A Mendelian randomization study

Metabolic disorders have been identified as an important factor causing nervous system diseases. However, due to the interference of confounding factors, the causal relationship between them has not been clearly elucidated, so it is necessary to study the causal relationship between them. To explore the causal relationship between blood metabolites and vertigo by Mendelian randomization. To assess causality, the inverse variance weighting method was employed as the primary analytical approach, complemented by additional sensitivity analyses. Metabolic pathway enrichment analysis and genetic correlation analysis were employed to further assess the metabolites. All statistical analyses were conducted using the R software. The study employed metabolite Genome Wide Association Study and vertigo diseases summary data sets to examine the causal relationship between 486 blood metabolites and 3 types of vertigo. A total of 55 potential metabolites associated with the 3 types of vertigo were identified, with 22, 16, and 13 candidate metabolites showing relatively reliable MR Evidence for Vestibular Dysfunction, Peripheral Vertigo, and Central Vertigo, respectively. Enrichment analysis was conducted to investigate the biological significance of these candidate metabolites, resulting in the identification of 7 key metabolic pathways across the 3 diseases, the metabolic pathway known as "Valine, leucine, and isoleucine biosynthesis" was found to be associated with all 3 types of vertigo, suggesting its potential influence on the vestibular system. Genetic correlation analysis revealed a genetic correlation between X-10510 and dodecanedioate with Vestibular Dysfunction. This study offers novel perspectives on the causal impact of blood metabolites on vertigo through the integration of genomics and metabolomics. Identifying metabolites that contribute to vertigo could serve as potential biomarkers and contribute to a better understanding of the underlying biological mechanisms associated with vertigo.

Cajal's contributions to vestibular research

The Spanish neurohistologist Santiago Ramón y Cajal (1852-1934) is widely regarded as the father of modern Neuroscience. In addition to identifying the individuality of cells in the nervous system (the neuron theory) or the direction followed by nerve impulses (the principle of dynamic polarization), he described numerous details regarding the organization of the different structures of the nervous system. This task was compiled in his magnum opus, "Textura del Sistema Nervioso del Hombre y los Vertebrados," first published in Spanish between 1899 and 1904, and later revised and updated in French as "Histologie du système nerveux de l'homme et des vertébrés" between 1909 and 1911 for wider distribution among the international scientific community. Some of Cajal's findings are fundamental to our understanding of the anatomy and histology of the vestibular system. He depicted the nerve endings in the sensory epithelia, the structure of the vestibular nerve and Scarpa ganglion, afferent vestibular fibers, vestibular nuclei, lateral vestibulospinal tract, vestibulocerebellar connections, and the fine structure of the cerebellum. However, most of these pioneering descriptions were published years earlier in Spanish journals with limited circulation. Our study aimed to gather Cajal's findings on the vestibular system and identify his original publications. After this endeavor, we claim a place for Cajal among the founders of anatomy and histology of the vestibular system.

Evaluation of Balance with Computerized Dynamic Posturography in Children with Otitis Media

BACKGROUND

Otitis media with effusion (OME) frequently leads to vestibular symptoms in children. However, young children face difficulty expressing their symptoms due to their limited language abilities.

METHODS

The balance of study and patient group evaluated with computer dynamic posturography, single-leg stance test with eyes closed and regular Head Impulse Test. The study group was assessed once again after the insertion of a ventilation tube two months later.

RESULTS

In the Sensory Organization Test, the scores for conditions 5, 6, and composite equilibrium of the preoperative patient group were notably lower compared with both the control and postoperative patient groups (p < 0.05). Additionally, a significant correlation was found between single-leg stance test with eyes closed results and conditions 5, 6, and composite equilibrium scores.

CONCLUSION

The impact of OME on the vestibular system is negative. This effect can be objectively assessed using Computer Dynamic Posturography and following tube insertion, there is a notable improvement in vestibular function. Furthermore, the single-leg stance (SLS) test with eyes closed has shown its reliability in assessing balance disorders, notably in children with OME.

LEVEL OF EVIDENCE

2 Laryngoscope, 134:4126-4133, 2024.

Unreliable association between self-reported sense of direction and peripheral vestibular function

BACKGROUND

Uni- or bilateral peripheralvestibular impairment causes objective spatial orientation deficits, which can be measured using pen-and-paper-tests or sensorimotor tasks (navigation or pointing). For patients' subjective orientation abilities, questionnaires are commonly used (e.g., Santa Barbara sense of direction scale [SBSODS]). However, the relationship between subjective assessment of spatial skills and objective vestibular function has only been scarcely investigated.

METHODS

A total of 177 patients (mean age 57.86 ± 17.53 years, 90 females) who presented in our tertiary Center for Vertigo and Balance Disorders underwent neuro-otological examinations, including bithermal water calorics, video head impulse test (vHIT), and testing of the subjective visual vertical (SVV), and filled out the SBSODS (German version). Correlation analyses and linear multiple regression model analyses were performed between vestibular test results and self-assessment scores. Additionally, groupwise vestibular function for patients with low, average, and high self-report scores was analyzed.

RESULTS

Forty-two patients fulfilled the diagnostic criteria for bilateral vestibulopathy, 93 for chronic unilateral vestibulopathy (68 unilateral caloric hypofunction and 25 isolated horizontal vestibulo-ocular reflex deficits), and 42 patients had normal vestibular test results. SBSODS scores showed clear sex differences with higher subjective skill levels in males (mean score males: 4.94 ± 0.99, females 4.40 ± 0.94; Student's t-test: t-3.78, p < .001***). No stable correlation between objective vestibular function and subjective sense of spatial orientation was found. A multiple linear regression model could not reliably explain the self-reported variance. The three patient groups with low, average, and high self-assessment-scores showed no significant differences of vestibular function.

CONCLUSION

Self-reported assessment of spatial orientation does not robustly correlate with objective peripheral vestibular function. Therefore, other methods of measuring spatial skills in real-world and virtual environments are required to disclose orientation deficits due to vestibular hypofunction.

Vestibular Neurostimulation for Parkinson's Disease: A Novel Device-Aided Non-Invasive Therapeutic Option

Dopaminergic replacement therapy remains the mainstay of symptomatic treatment for Parkinson's disease (PD), but many unmet needs and gaps remain. Device-based treatments or device-aided non-oral therapies are typically used in the advanced stages of PD, ranging from stereotactic deep brain stimulation to levodopa or apomorphine infusion therapies. But there are concerns associated with these late-stage therapies due to a number of procedural, hardware, or long-term treatment-related side effects of these treatments, and their limited nonmotor benefit in PD. Therefore, there is an urgent unmet need for low-risk adjuvants or standalone therapies which can address the range of burdensome motor and nonmotor symptoms that occur in PD. Recent studies suggest that non-invasive neurostimulation of the vestibular system may be able to address these gaps through the stimulation of the vestibular brainstem sensory network which extensively innervates brain regions, regulating both motor and a range of nonmotor functions. Therapeutic non-invasive vestibular stimulation is a relatively modern concept that may potentially improve a broad range of motor and nonmotor symptoms of PD, even at early stages of the disease. Here, we review previous studies supporting the therapeutic potential of vestibular stimulation for the treatment of PD and discuss ongoing clinical trials and potential areas for future investigations.

Perinatal adversities as a common factor underlying the association between atypical laterality and neurodevelopmental disorders: A developmental perspective

Several neurodevelopmental disorders are associated with a higher prevalence of atypical laterality (e.g., left-handedness). Both genetic and non-genetic factors play a role in this association, yet the underlying neurobiological mechanisms are largely unclear. Recent studies have found that stress, mediated by the hypothalamic-pituitary-adrenal (HPA) axis, could be linked to laterality development. These findings provide an opportunity to explore new theoretical perspectives on the association between atypical laterality and neurodevelopmental disorders. This article aims to provide a theoretical framework demonstrating how perinatal adversities could disrupt the typical developmental trajectories of both laterality and neurodevelopment, potentially impacting both the HPA axis and the vestibular system. Additionally, we argue that the relationship between atypical laterality and neurodevelopmental disorders cannot be understood by simply linking genetic and non-genetic factors to a diagnosis, but the developmental trajectories must be considered. Based on these ideas, several perspectives for future research are proposed.

Simultaneous recordings from vestibular Type I hair cells and their calyceal afferents in mice

The vestibular hair cell receptors of anamniotes, designated Type II, are presynaptic to bouton endings of vestibular nerve distal neurites. An additional flask-shaped hair cell receptor, Type I, is present in amniotes, and communicates with a chalice-shaped afferent neuritic ending that surrounds the entire hair cell except its apical neck. Since the full repertoire of afferent fiber dynamics and sensitivities observed throughout the vertebrate phyla can be accomplished through Type II hair cell-bouton synapses, the functional contribution(s) of Type I hair cells and their calyces to vestibular performance remains a topic of great interest. The goal of the present study was to investigate electrical coupling between the Type I hair cell and its enveloping calyx in the mouse semicircular canal crista ampullaris. Since there are no gap junctions between these two cells, evidence for electrical communication would necessarily involve other mechanisms. Simultaneous recordings from the two cells of the synaptic pair were used initially to verify the presence of orthodromic quantal synaptic transmission from the hair cell to the calyx, and then to demonstrate bi-directional communication due to the slow accumulation of potassium ions in the synaptic cleft. As a result of this potassium ion accretion, the equilibrium potentials of hair cell conductances facing the synaptic cleft become depolarized to an extent that is adequate for calcium influx into the hair cell, and the calyx inner face becomes depolarized to a level that is near the threshold for spike initiation. Following this, paired recordings were again employed to characterize fast bi-directional electrical coupling between the two cells. In this form of signaling, cleft-facing conductances in both the hair cell and calyx increase, which strengthens their coupling. Because this mechanism relies on the cleft resistance, we refer to it as resistive coupling. We conclude that the same three forms of hair cell-calyceal transmission previously demonstrated in the turtle are present in the mammalian periphery, providing a biophysical basis for the exceptional temporal fidelity of the vestibular system.

A Month of Vestibular Migraine: Symptom Characterization Using Ecological Momentary Assessment

OBJECTIVE(S)

This study investigated the frequency and intensity of vestibular migraine (VM) symptoms using Ecological Momentary Assessment (EMA). This approach was intended to provide insights into the day-to-day experiences of individuals with VM, contributing to a more comprehensive understanding of this condition.

METHODS

Participants reported symptoms to an automated text system, rating their dizziness over the prior 24 h as none, mild, moderate, or severe. Definitive Dizzy Days (DDDs) were defined as days with moderate or severe dizziness. A student's independent group t-test was used to compare the number of DDDs between VM and probable VM subjects.

RESULTS

Sixty-six subjects were included, with an average of 29 days of pre-intervention data (SD = 1.4). The average number of days with no dizziness was 3.5 (SD = 6.5), mild dizziness was 9.1 (SD = 6.7), moderate dizziness was 11 (SD = 6.1), and severe dizziness was 5.4 (SD = 6.3). Out of the 66 patients, 52 were classified as VM and 14 as pVM. The average number of DDDs was not significantly different between VM (17.0, SD = 8.3) and pVM (15.3, SD = 10.0) patients, with a two-tailed p-value of 0.44.

CONCLUSION

With EMA, we found that the average subject with VM had some degree of dizziness almost every day, and more than 15 DDDs per month.

LEVEL OF EVIDENCE

III Laryngoscope, 2024.

Normative values to Horus® computerized posturography in children

PURPOSE

Propose normalization values of the Horus® computerized posturography platform, in children aged 4 to 6 years, without auditory and/or vestibular complaints.

METHODS

Cross-sectional study, 216 children aged 4 to 6 years participated. All the children underwent to visual screening, audiological evaluation and computerized posturography, which consists of research on stability limits and seven sensory conditions. The results were statistically analyzed using the tests non-parametric Kruskal-Walli, post hoc Dunn-Bonferroni for pairwise age comparisons and the Mann-Whitney U for sex analysis. Categorical data were presented in relative frequency and quantitative data in mean and standard deviation.

RESULTS

Standardization values were described for the stability limit and for the seven sensory conditions. There was a difference for the stability limit between sex at 4 years old(p<0.007) and, in the comparison between ages 4 and 5 (p=0.005) and 4 and 6 years old(p<0.001). In the residual functional balance, comparison between ages, there was a difference between 4 and 5, 4 and 6, 5 and 6 years, however for different data. The presence of statistical difference for different evaluation data also occurred in the analysis by sex. In the sensory systems, the findings between ages showed differences for the vestibular system, right and left optokinetic visual dependence, tunnel visual dependence and for the composite balance index.

CONCLUSION

It was possible to establish normative values for the Horus® posturography in healthy children aged 4 to 6 years.

French adaptation and validation of the Niigata PPPD Questionnaire: measure of severity of Persistent Postural-Perceptual Dizziness and its association with psychiatric comorbidities and perceived handicap

Persistent Postural-Perceptual Dizziness (PPPD) is a functional vestibular condition. Despite being the most common chronic neuro-otologic disorder, it remains undertreated. The Niigata PPPD Questionnaire (NPQ), developed by Yagi et al. in 2019 to assess the severity of PPPD, could be a useful tool to help in the screening and diagnosis of this condition. This study aimed to validate a French version of the NPQ and make it an available assessment tool. Moreover, we aimed to understand the characteristics of PPPD patients better. The NPQ was translated and adapted into French. 50 PPPD patients, 50 patients with vestibular disorders without PPPD, and 50 healthy controls were included. They answered the adapted NPQ and additional questionnaires assessing trait (STAI) and state anxiety (HADS-A), depression (HADS-D) and handicap related to dizziness (DHI). The NPQ's reliability was assessed by Cronbach's alpha. Intergroup comparisons and multiple linear regressions were conducted to examine the characteristics of PPPD patients compared to vestibular patients and healthy controls, to validate NPQ's reliability, and to explore the effect of clinical parameters and treatment with selective serotonin reuptake inhibitors. Receiver operating characteristic (ROC) curves were carried out to determine the diagnostic values of the NPQ total score and sub-scores. Relations between NPQ and reported handicap, depression and anxiety were evaluated by correlations between questionnaire scores. The internal consistency was high (>0.8) for all NPQ subscales and the total score. Intergroup comparisons showed a significantly higher NPQ total score and sub-scores in the PPPD group compared to the two others. The ROC curve analysis showed a significant, but poor, discrimination of NPQ (AUC = 0.664) and its subscales. DHI scores, depressive symptoms and trait anxiety were significantly higher in PPPD patients than in vestibular patients and healthy controls. State anxiety did not differ between patients with PPPD and vestibular patients without PPPD. Finally, there was a significant correlation between the NPQ and the DHI. Our study provides a better understanding of PPPD symptomatology and its assessment. It showed that the NPQ is a reliable tool that can assist in symptom assessment for a French-speaking population.

Review of chaos in hair-cell dynamics

The remarkable signal-detection capabilities of the auditory and vestibular systems have been studied for decades. Much of the conceptual framework that arose from this research has suggested that these sensory systems rest on the verge of instability, near a Hopf bifurcation, in order to explain the detection specifications. However, this paradigm contains several unresolved issues. Critical systems are not robust to stochastic fluctuations or imprecise tuning of the system parameters. Further, a system poised at criticality exhibits a phenomenon known in dynamical systems theory as critical slowing down, where the response time diverges as the system approaches the critical point. An alternative description of these sensory systems is based on the notion of chaotic dynamics, where the instabilities inherent to the dynamics produce high temporal acuity and sensitivity to weak signals, even in the presence of noise. This alternative description resolves the issues that arise in the criticality picture. We review the conceptual framework and experimental evidence that supports the use of chaos for signal detection by these systems, and propose future validation experiments.

Vestibular Rehabilitation Using Dynamic Posturography: Objective and Patient-Reported Outcomes from a Randomized Trial

OBJECTIVE

Balance deficits are common and debilitating. Standard treatments have limitations in addressing symptoms and restoring dynamic balance function. This study compares a rehabilitative computerized dynamic posturography (CDP) protocol, computerized vestibular retraining therapy (CVRT), with a home exercise program (HEP) for patients with objectively confirmed unilateral vestibular deficits (UVDs).

STUDY DESIGN

Single-center, randomized, interventional trial, with 1-sided crossover.

SETTING

A tertiary neurotology clinic.

METHODS

Patients with UVDs and Dizziness Handicap Inventory (DHI) score >30 were randomized to receive either CVRT or HEP. After completion of treatment, the HEP group was crossed over to CVRT. Outcome measures were the sensory organization test (SOT) and 3 participants reported dizziness disability measures: the DHI, Activity-Specific Balance Confidence Scale (ABC) scale, and Falls Efficacy Score-International (FES-I).

RESULTS

We enrolled 37 patients: 18 participants completed CVRT and 12 completed HEP, 11 of whom completed the crossover. Seven participants withdrew. The CVRT group demonstrated a greater improvement in SOT composite score than the HEP group (P = .04). Both groups demonstrated improvement in participant-reported measures but there were no differences between groups (DHI: P = .2604; ABC: P = .3627; FES-I: P = .96). Following crossover to CVRT after HEP, SOT composite (P = .002), DHI (P = .03), and ABC (P = .006) improved compared to HEP alone.

CONCLUSION

CVRT and HEP were both associated with improved participant-reported disability outcomes. CVRT was associated with greater improvement in objective balance than HEP. Adding CVRT after HEP was superior to HEP alone. Multimodal CDP-based interventions, such as CVRT, should be considered as an adjunct to vestibular physiotherapy for patients with UVD.

Vertiginous epilepsy in the pediatric population

Vertiginous epilepsy (VE) is a rare and underrecognized epilepsy subtype in the pediatric population. Vertiginous symptoms are the sole or predominant feature, arise from the vestibular cortex, and seizures are usually brief. The incidence is estimated to be between six and 15 percent of pediatric patients presenting with dizziness. Diagnosis is often delayed for many years following the onset of symptoms, as there are no widely accepted diagnostic criteria. Diagnostic work-up should include a detailed history, physical exam, EEG, and brain imaging with MRI. Vestibular testing is helpful if peripheral vestibulopathy is suspected. Vertiginous epilepsy can have many possible causes, but a large majority are idiopathic or suspected to be genetic. Most patients with vertiginous epilepsy achieve seizure freedom with anti-seizure medications.

Human senses and sensors from Aristotle to the present

This historical review on the semantic evolution of human senses and sensors revealed that Aristotle's list of the five senses sight, hearing, touch, taste, and smell is still in use among non-scientific lay persons. It is no surprise that his classification in the work "De Anima" (On the Soul) from 350 BC confuses the sensor "touch" with the now more comprehensively defined somatosensory system and that senses are missing such as the later discovered vestibular system and the musculotendinous proprioception of the position of parts of the body in space. However, it is surprising that in the three most influential ancient cultures, Egypt, Greece, and China-which shaped the history of civilization-the concept prevailed that the heart rather than the brain processes perception, cognition, and emotions. This "cardiocentric view" can be traced back to the "Doctrine of Aristotle," the "Book of the Dead" in ancient Egypt, and the traditional Chinese medicine of correspondence documented in the book "Huang di Neijing." In Greek antiquity the philosophers Empedocles, Democritus and Aristotle were proponents of the allocation of the spirit and the soul to the heart connected to the body via the blood vessels. Opponents were the pre-Socratic mathematician Pythagoras, the philosopher Plato, and especially the Greek physician Hippocrates who regarded the brain as the most powerful organ in humans in his work "De Morbo Sacro." The Greek physician Galen of Pergamon further elaborated on the concept of the brain ("cephalocentric hypothesis") connected to the body by a network of nerves. The fundamental concepts for understanding functions and disorders of the vestibular system, the perception of self-motion, verticality and balance control were laid by a remarkable group of 19th century scientists including Purkynӗ, Mach, Breuer, Helmholtz, and Crum-Brown. It was also in the 19th century that Bell described a new sense of a reciprocal sensorimotor loop between the brain and the muscles which he called "muscular sense," later termed "kinaesthesia" by Bastian and defined in 1906 as "proprioception" by Sherrington as "the perception of joint and body movements as well as position of the body or body segments, in space." Both, the vestibular system and proprioception could be acknowledged as senses six or seven. However, we hesitate to recommend "pain"-which is variously assigned to the somatosensory system or extero-, intero-, visceroception-as a separate sensory system. Pain sensors are often not specific but have multisensory functions. Because of this inconsistent, partly contradictory classification even by experts in the current literature on senses and sensors we consider it justified to recommend a comprehensive reorganization of classification features according to the present state of knowledge with an expansion of the number of senses. Such a project has also to include the frequent task-dependent multisensory interactions for perceptual and sensorimotor achievements, and higher functions or disorders of the visual and vestibular systems as soon as cognition or emotions come into play. This requires a cooperation of sensory physiologists, neuroscientists and experienced physicians involved in the management of patients with sensory and multisensory disorders.

Evaluation of the audiovestibular system before and after treatment in patients with Idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) can affect both hearing and balance due to increased inner ear pressure.

AIMS/OBJECTIVES

This study aimed to evaluate the impact of increased inner ear pressure on hearing and balance in patients with IIH using auditory and vestibular tests.

MATERIAL AND METHODS

Twenty-four IIH patients and 28 healthy controls underwent oVEMP, pure tone audiometry, tympanometry, and acoustic reflex tests pre-lumbar punctures. IIH patients received acetazolamide. Pre- and post-treatment results, tinnitus, and vertigo scores were compared. Post-treatment oVEMP and audiometry results were compared between groups.

RESULTS

Pre-treatment oVEMP showed a significant left N1 latency difference (p = 0.049). Post-treatment, left ear amplitude (p = 0.035) and both ear amplitude ratios (p = 0.044 and p = 0.047) increased significantly. Audiometry had no significant changes (p < 0.05). Tinnitus and vertigo scores decreased significantly (p ≤ 0.001).

CONCLUSION

Prolonged oVEMP latency suggests IIH may impact the brain stem and vestibular nerve, while increased amplitude values indicate peripheral vestibular involvement. IIH affects hearing across all frequencies, especially at 4000 Hz, impacting both hearing and balance.

SIGNIFICANCE

Understanding the effects of IIH on auditory and vestibular functions can guide effective treatments, improving quality of life for patients by addressing both hearing and balance issues.

Improved Recovery after Vestibular Schwannoma Excision with Intratympanic Gentamicin Prehabilitation

OBJECTIVE

Translabyrinthine excision of a vestibular schwannoma is associated with acute vestibular failure. Preoperative intratympanic gentamicin (ITG) injections can improve objective balance function after surgery but its clinical benefits remain to be established.

METHODS

Adult patients undergoing translabyrinthine removal of a vestibular schwannoma between January 2014 and February 2018 underwent preoperative vestibular function testing. Patients were divided in to 3 groups, those with vestibular function (VF) who received ITG injections, those with VF but did not receive ITG and those with no VF. Groups were compared according to degree of vertigo, length of stay, time to unassisted mobilization, and postoperative anti-emetic consumption.

RESULTS

Forty six patients had ITG injections (Group 1), 7 had residual VF but refused treatment (Group 2), 21 had no VF (Group 3). Group 1 had a significant improvement in vertigo over time whereas groups 2 and 3 did not. There was a statistically significant 70% decrease in time to independent mobilization between Group 1 and other groups and a 19% decrease in length of stay in Group 1 compared to other groups although this did not reach statistical significance. Two patients had injection-related complications. Group 1 used less anti-emetics than other groups but this was not statistically significant.

CONCLUSION

Preoperative intratympanic gentamicin injection with vestibular rehabilitation exercises is associated with less postoperative vertigo and earlier postoperative mobilization. There was reduced duration of hospitalization and decreased consumption of anti-emetic but not significantly so possibly because of low numbers of patients in the no treatment group.

LEVEL OF EVIDENCE

2 Laryngoscope, 134:3316-3322, 2024.

An Evaluation of the Vestibular System in Individuals Aged 40-65 Years with Sensorineural Hearing Loss

Objectives

Vestibular dysfunction occasionally accompanies sensorineural hearing loss (SNHL) due to anatomical proximity of cochlea and vestibule. The aim of the present study was to evaluate the vestibular system objectively and subjectively in 40-to 65-year-old individuals with and without SNHL.

Methods

This study included participants of both sexes, between the ages of 40 and 65 years old. There were 31 participants with SNHL and 31 control participants. First of all, participants were grouped in the control and SNHL groups based on the results of their hearing test, which included audiometry and immitance evaluation. Subsequently, for vestibular evaluation, each participant was evaluated subjective with "Dizziness Handicap Inventory" (DHI) as well as with objective tests battery that included positional tests with videonystagmogrophy (VNG) and vestibuloocular reflex (VOR) assessment using the vestibular head impulse test (vHIT).

Results

Peripheral nystagmus was found to be significantly higher in patients with SNHL based on the head shake and positional tests (p<0.05). There was a positive correlation between DHI scores and positional test findings of the participants with SNHL (p<0.05). When the VHIT VOR gain values were compared between groups, there was no significant difference (p<0.05).

Conclusion

In our study, vestibular involvement was frequently observed in 40- to 65-year-old individuals with SNHL. Therefore, vestibular evaluation should be considered along with the assessment of hearing in individuals with SNHL who are over 40 years old.

Head movements induced by voluntary neck flexion stabilize sensorimotor synchronization of the finger to syncopated auditory rhythms

Head movements that are synchronized with musical rhythms often emerge during musical activities, such as hip hop dance. Although such movements are known to affect the meter and pulse perception of complex auditory rhythms, no studies have investigated their contribution to the performance of sensorimotor synchronization (SMS). In the present study, participants listened to syncopated auditory rhythms and flexed their dominant hand index finger in time with the perceived pulses (4/4 meters). In the first experiment (Exp. 1), the participants moved their heads via voluntary neck flexion to the pulses in parallel with finger SMS (Nodding condition, ND). This performance was compared with finger SMS without nodding (Without Nodding condition, WN). In the second experiment (Exp. 2), we investigated the specificity of the effect of head SMS on finger SMS confirmed in Exp. 1 by asking participants to flex their bilateral index fingers to the pulses (Bimanual condition, BM). We compared the performance of dominant hand finger SMS between the BM and ND conditions. In Exp. 1, we found that dominant hand finger SMS was significantly more stable (smaller standard deviation of asynchrony) in the ND versus WN condition (p < 0.001). In Exp. 2, dominant hand finger SMS was significantly more accurate (smaller absolute value of asynchrony) in the ND versus BM condition (p = 0.037). In addition, the stability of dominant hand finger SMS was significantly correlated with the index of phase locking between the pulses and head SMS across participants in the ND condition (r = -0.85, p < 0.001). In contrast, the stability of dominant hand finger SMS was not significantly correlated with the index of phase locking between pulses and non-dominant hand finger SMS in the BM condition (r = -0.25, p = 0.86 after multiple comparison correction). These findings suggest that SMS modulation depends on the motor effectors simultaneously involved in synchronization: simultaneous head SMS stabilizes the timing of dominant hand finger SMS, while simultaneous non-dominant hand finger SMS deteriorates the timing accuracy of dominant hand finger SMS. The present study emphasizes the unique and crucial role of head movements in rhythmic behavior.

Vestibular dysfunction in Parkinson's disease: a neglected topic

Dizziness and postural instability are frequently observed symptoms in patient with Parkinson's disease (PD), potentially linked to vestibular dysfunction. Despite their significant impact on quality of life, these symptoms are often overlooked and undertreated in clinical practice. This review aims to summarize symptoms associated with vestibular dysfunction in patients with PD and discusses vestibular-targeted therapies for managing non-specific dizziness and related symptoms. We conducted searches in PubMed and Web of Science using keywords related to vestibular dysfunction, Parkinson's disease, dizziness, and postural instability, alongside the reference lists of relevant articles. The available evidence suggests the prevalence of vestibular dysfunction-related symptoms in patients with PD and supports the idea that vestibular-targeted therapies may be effective in improving PD symptoms.

Inner ear morphology in wild versus laboratory house mice

The semicircular canals of the inner ear are involved in balance and velocity control. Being crucial to ensure efficient mobility, their morphology exhibits an evolutionary conservatism attributed to stabilizing selection. Release of selection in slow-moving animals has been argued to lead to morphological divergence and increased inter-individual variation. In its natural habitat, the house mouse Mus musculus moves in a tridimensional space where efficient balance is required. In contrast, laboratory mice in standard cages are severely restricted in their ability to move, which possibly reduces selection on the inner ear morphology. This effect was tested by comparing four groups of mice: several populations of wild mice trapped in commensal habitats in France; their second-generation laboratory offspring, to assess plastic effects related to breeding conditions; a standard laboratory strain (Swiss) that evolved for many generations in a regime of mobility reduction; and hybrids between wild offspring and Swiss mice. The morphology of the semicircular canals was quantified using a set of 3D landmarks and semi-landmarks analyzed using geometric morphometric protocols. Levels of inter-population, inter-individual (disparity) and intra-individual (asymmetry) variation were compared. All wild mice shared a similar inner ear morphology, in contrast to the important divergence of the Swiss strain. The release of selection in the laboratory strain obviously allowed for an important and rapid drift in the otherwise conserved structure. Shared traits between the inner ear of the lab strain and domestic pigs suggested a common response to mobility reduction in captivity. The lab-bred offspring of wild mice also differed from their wild relatives, suggesting plastic response related to maternal locomotory behavior, since inner ear morphology matures before birth in mammals. The signature observed in lab-bred wild mice and the lab strain was however not congruent, suggesting that plasticity did not participate to the divergence of the laboratory strain. However, contrary to the expectation, wild mice displayed slightly higher levels of inter-individual variation than laboratory mice, possibly due to the higher levels of genetic variance within and among wild populations compared to the lab strain. Differences in fluctuating asymmetry levels were detected, with the laboratory strain occasionally displaying higher asymmetry scores than its wild relatives. This suggests that there may indeed be a release of selection and/or a decrease in developmental stability in the laboratory strain.