The cortical vestibular system: insights from electroencephalography

Partial or total unilateral vestibular loss is the third most common cause of peripheral vestibular dysfunction. Dysfunction of one or both of the vestibular mechanisms can manifest physically as abnormalities of posture, balance, and/or visual acuity. This case report describes physical therapy examination and individualized intervention with vestibular rehabilitation for a patient with unilateral vestibular hypofunction. The patient was an 80-year-old male with electronystamographically confirmed unilateral vestibular loss of 98.3%. He demonstrated altered balance and gaze stability classifying him as having an increased risk for falling. After 5 weeks of individualized vestibular rehabilitation, the patient significantly decreased his fall risk from 11 to 20 of 24 on the Dynamic Gait Index. His gaze stability also improved from a 4 to 1 line disparity with dynamic visual acuity testing. The patient also had a decrease in perceived disability on the Dizziness Handicap Inventory from 30/100 at evaluation to 12/100 at discharge. Individualized vestibular rehabilitation decreased fall risk and improved gaze stability for a patient with significant unilateral vestibular hypofunction.

Vestibular disorder is the cause of approximately 50% of dizziness in older people. The vestibular system is a critical postural control mechanism, and posturography analysis is helpful for diagnosing vestibular disorder. In clinical practice, the sensory organization test (SOT) is used to quantify postural control in an upright stance under different test conditions. However, both aging and vestibular disorder cause declines of postural control mechanisms. The aim of this study was to enhance the performance of the SOT using a nonlinear algorithm of empirical mode decomposition (EMD) and to verify the differences of effects caused by aging and/or illnesses benefits to clinical diagnosis. A total of 51 subjects belonging to 3 groups—healthy-young, healthy-elderly and dizzy—were recruited for this study. New dynamic parameters of the SOT were derived from the center of pressure (COP) signals. EMD served as an adaptive filter bank to derive the low- and high-frequency components of the COP. The effects on four ratios of sensory analysis caused by aging and vestibular disorder can be investigated for the specific frequency bands. According to our findings, new SOT parameters derived from the component with the specific frequency band more sensitively reflect the functional condition of vestibular dysfunction. Furthermore, both aging and vestibular dysfunction caused an increase in magnitude for the low-frequency component of the AP-direction COP time series. In summary, the low-frequency fluctuation reflects the stability of postural control, while the high-frequency fluctuation is sensitive to the functional condition of the sensory system. EMD successfully improved the accuracy of SOT measurements in this investigation.

Evaluation of vestibular symptoms and postural balance control in patients with chronic otitis media.

Electricity and vibration were two commonly used physical agents to provide vestibular stimulation in previous studies. This study aimed to systematically review the effects of galvanic (GVS) and vibration-based vestibular stimulation (VVS) on gait performance and postural control in healthy participants. Five bioscience and engineering databases, including MEDLINE via PubMed, CINAHL via EBSCO, Cochrane Library, Scopus, and Embase, were searched until March 19th, 2023. Studies published between 2000 and 2023 in English involving GVS and VVS related to gait performance and postural control were included. The procedure was followed via the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The methodological quality of included studies was assessed using the NIH study quality assessment tool for observational cohort and cross-sectional studies. A total of 55 cross-sectional studies met the inclusion criteria and were included in this study. Five studies were good-quality while 49 were moderate-quality and 1 was poor-quality. There were 50 included studies involving GVS and 5 included studies involving VVS. GVS and VVS utilized different physical agents to provide vestibular stimulation and demonstrated similar effects on vestibular perception. Supra-threshold GVS and VVS produced vestibular perturbation that impaired gait performance and postural control, while sub-threshold GVS and VVS induced stochastic resonance phenomenon that led to an improvement. Bilateral vestibular stimulation demonstrated a greater effect on gait and posture than unilateral vestibular stimulation. Compared to GVS, VVS had the characteristics of better tolerance and fewer side effects, which may substitute GVS to provide more acceptable vestibular stimulation.

Does cochlear implantation influence postural stability in patients with hearing loss?

IntroductionThe consequence of complete or partial uncompensated vestibular dysfunction in children is usually balance disorders, with the risk of falls and increased fatigue, particularly during tasks requiring postural control. The aim of these recommendations is to establish guidelines for vestibular rehabilitation (VR) in children with vestibular impairment. Material and methodsThe guidelines were developed based on a systematic review of the international literature, validated by a multidisciplinary group of French-speaking otorhinolaryngologists, scientists, and physiotherapists. They are classified as grade A, B, C, or expert opinion according to a decreasing level of scientific evidence. ResultsA PubMed search of studies published between January 1990 and December 2021 was carried out using the keywords “vestibular,” “rehabilitation,” and “children”. After filtering and reviewing the articles, a total of 10 publications were included to establish the recommendations. ConclusionIt is recommended that a vestibular assessment be carried out before VR, including a study of vestibulo-ocular reflex, otolithic function, and postural control. In cases of vestibular dysfunction, physiotherapy treatment is recommended from an early age to train different aspects of postural control, including anticipatory and reactive postural adjustments. VR adapted to the pediatric population is recommended for children whose vestibular dysfunction leads to functional disorders or symptoms of vertigo for those who have suffered head trauma. It is recommended that children with bilateral vestibular impairment be treated using gaze stabilization exercises for adaptation and substitution. Optokinetic stimulation and virtual reality are not recommended for children and young adolescents.

Personality traits modulate subcortical and cortical vestibular and anxiety responses to sound-evoked otolithic receptor stimulation

Vestibular rehabilitation has come a long way from Cawthorne and Cooksey exercises. Although revolutionary in their foresight and still in use today, the available options for rehabilitation of vestibular disorders has dramatically in recent years. Currently in our armamentarium are specific exercises to address gaze instability, postural instability (static and dynamic), motion sensitivity, and vertigo—all symptoms relative to pathology within the peripheral and central vestibular pathways. Cochrane studies have established that vestibular rehabilitation is effective for treating unilateral peripheral vestibular hypofunction. Recent treatment guidelines and systematic reviews suggest that repositioning maneuvers are the superior treatment for benign paroxysmal positional vertigo. Our knowledge of testing and treatment of pathologies affecting the peripheral vestibular labyrinth and/or the pathways mediating vestibular afference is exploding. Just as optimal intervention for individuals with vestibular disorders commonly involves multiple disciplines, so are multiple disciplines conducting excellent research that demands vigilance in the practicing clinician. As clinicians who treat people with vestibular disorders, our interventions would be enhanced by examining data from other disciplines: emerging evidence suggests that new tests may isolate utricular from saccular function, migraines can be triggered by vestibular stimulation, and technical advances in oculomotor equipment now enable video monitoring and recording of rapid head and eye rotations. Today there are many tests that can be used by clinicians, which provide clinically meaningful information. In addition, as members of the vestibular team, physical therapists need to become more involved in other professional meetings to inform other clinicians about what we have to offer. Important opportunities for collaborating might involve the American Academy of Head and Neck Surgery, the Association for Research in Otolaryngology, and the biannual Barany Society meeting. We are pleased to report that this Special Issue of the JNPT has and outstanding cadre of international authors and coauthors from the United States, the United Kingdom, Greece, Saudi Arabia, Jordan, and Australia. The topics covered are diverse and so is the authors' expertise. The authors include physical therapists, engineers, and physicians who work to enhance the care of persons with vestibular disorders. The authors were asked to contribute to this issue based on their novel work, and we hope that their recent findings help to improve care for your patients. Most of the articles in this Special Issue include advanced technology as part of their methods. The use of the vibrotactors (Wall), scleral search coils (Scherer and Schubert), uniquely applied measures of attention (Mohammad et al), and optokinetic stimulation (Pavlou et al) all involve some degree of innovative technology to assess treatment effectiveness, measurement of vestibular function, or reveal behavior in people with vestibular dysfunction. Other articles in this issue attempt to describe treatment effectiveness in interesting patient groups including mild traumatic brain injury related to blunt (Alsalaheen et al) and blast (Gottshall) trauma, patients with report of dizziness but normal caloric findings (Hall et al), patients with canal-only versus canal and otolith dysfunction (Murray et al), and differences between treatment paradigms (Clendaniel). The future for vestibular rehabilitation is exciting and will involve interaction with multiple disciplines. In a recent survey of biomechanics laboratories, physical therapists who responded to an informal survey participated in projects in >75% of the laboratories. Physical therapists were the largest group represented at the 2010 International Gait and Mental Function meeting. In the future, we expect the merging of vestibular physical therapy with technical innovations to include virtual reality feedback/training, a vestibular prosthesis, even stem cell research to resolve pathophysiology within the labyrinth. These new technologies will need the skills and knowledge of physical therapists to help investigators determine whether the interventions are effective and/or to establish the behavioral implications of stem cell physiology to restore function. Most certainly, other clinicians/researchers will look to physical therapists for better understanding of movement problems of people with vestibular and other neuromotor disorders, and for optimal rehabilitation approaches to maximize the value of technology. We encourage all readers to examine the foundational science and evidence for using new and innovative technologies before adopting the newest device for use with their patients. Material in this Special Issue was chosen to highlight some of the investigators around the world who are making a difference in the care of people with vestibular disorders. Many basic clinical questions remain, and we still struggle with issues such as optimal dose, optimal type of exercise, and the value of continuing a home exercise program after discharge. We hope that this Special Issue will help clinicians explore some new innovations and discoveries in physical therapist examination and treatment of persons with vestibular disorders.

The aim of this article is to demonstrate ENT specialists, neurologists and general practitioners how to examine and treat patients with acute vertiginous complaints. Traditional otoneurologic testing that carried out for accurate topic diagnostics of acute vestibular dysfunction is described as available «Vestibular passport». Clinical diagnosis can be achieved after thorough assessment of patient’s complaints as well as history of the present illness. Gaze tests and posture control trials are demonstrated in details. Diagnostic value of each probe is shown from the viewpoint of differential diagnostics of peripheral and central vestibular dysfunction. High diagnostic value of registration and analysis of oculogyric reactions is presented by history cases of acute labyrinthopathy and acute vestibular neuronitis. In these cases absence of saccadic and pursuit gaze disturbances rule out central vestibular system dysfunction. The salient feature of these two variants of peripheral vestibular dysfunction is spontaneous nystagmus that revealed by Frenzel glasses. This significant oculomotor symptom as well as disturbances of static and dynamic postural control confirm patient’s vestibular complaints in objective way. Revelation of decompensation signs of vestibular dysfunction needs urgent medicine vertigo therapy and spare vestibular rehabilitation. Actually, medications of choice are sedative drugs with antiemetic effect, non-loop diuretics and glucocorticoids.

Effects of Deep Brain Stimulation on Postural Control in Parkinson's Disease

BackgroundForward head posture (FHP) is a common postural deviation. An increasing number of studies have reported that people with FHP present with impaired postural control and gait; however, there is conflicting evidence. A systematic review focusing on these relationships has been unavailable to date. Research questionIs there a relationship between FHP, postural control and gait? MethodsThis systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement (PROSPERO ID: CRD42021231908). Web of Science, PubMed, Scopus, and CINAHL Plus (via EBSCO) were systematically searched, and a manual search was performed using the reference lists of included studies. Eligible studies included observational studies addressing the relationship between FHP, postural control and/or gait. Quality assessment was conducted using the Joanna Briggs Institute Critical Appraisal Checklist for Cross-Sectional Studies. ResultsNineteen studies were selected for this review. Consistent evidence supported that people with FHP had significant alterations in limits of stability (n = 3), performance-based balance (n = 3), and cervical proprioception (n = 4). Controversial evidence existed for a relationship of FHP with static balance (n = 4) and postural stability control (n = 4). Limited evidence existed to support an alteration in gait and vestibular function. Three studies on induced FHP consistently identified no reduced postural control. SignificanceCurrent evidence supports an association between FHP and a detrimental alteration in limits of stability, performance-based balance, and cervical proprioception. Instead of simply indicating impaired overall balance, the findings of this review indicate that a reduction in specific aspects of the postural control requires to be clarified in clinical evaluation for individuals with FHP, which would facilitate the planning and application of appropriate interventions to prevent dysfunctions and disability.

Interactions between anxiety and vestibular symptoms have been described since the late 1800s. Typically, they have been conceptualized as bidirectional effects of one condition on the other (i.e., anxiety disorders as a cause of vestibular symptoms and vestibular disorders as a cause of anxiety symptoms). Over the past 30 years, however, a steady progression of neurophysiological investigations of gait and stance under conditions of postural threat, neuroanatomical studies of connections between threat assessment and vestibular pathways in the brain, and clinical research on anxiety-related vestibular conditions has offered the building blocks of a more integrated model. In this newer concept, threat assessment is an integral component of spatial perception, postural control, and locomotion in health and disease. It is not imposed on the vestibular system from the outside or simply reactive to vestibular dysfunction, but an inherently necessary part of every aspect of mobility. In this article, the authors review evidence that supports this model and then use it to examine common neurotologic conditions in which anxiety-related processes play important roles-fear of falling, primary and secondary anxiety disorders in patients with vestibular symptoms, and chronic subjective dizziness.

Motion sickness is defined as a sensation of uneasiness that occurs during physical motion, such as transportation by bus, plane, car or train. Postural control is one of the multisensory processes that has been examined in individuals susceptible to motion sickness. Indeed, postural control relies on visual, somatosensory and vestibular information. While studies suggest normal-like postural control during quiet standing, others suggest that individuals with motion sickness show increased postural instability during sensory perturbations, namely during visual and somatosensory disturbances. The impact of vestibular stimulation on postural control in individuals with motion sickness has yet to be determined. Therefore, the aim of the present exploratory study was to examine the effects of sinusoidal electrical vestibular stimulation on postural control in individuals with varying degrees of motion sickness. Fifty participants were divided into three groups based their susceptibility to motion sickness. Participants were initially tested at baseline in the four postural conditions of the modified Clinical Test of Sensory Integration and Balance protocol (mCTSIB): eyes open on firm surface, eyes closed on firm surface, eyes open on foam surface, eyes closed on foam surface. These four conditions were then repeated during sinusoidal electrical vestibular stimulation (EVS) of 1mA at 1Hz. In baseline conditions, no significant group differences in postural control were found. Data in experimental (EVS) conditions, however, suggests that individuals with high susceptibility to motion sickness are more impacted by vestibular stimulation, specifically in the eyes closed on firm surface condition. It has been suggested that motion sickness could be the result of an altered multisensory integration process. While the present data do not allow us to answer this question, it would remain important to examine all types of sensory perturbations and combinations thereof in a larger group of individuals.

Posturography following Rotation: A Model of Posture Control during Vestibular Dysfunction

Introduction: A number of vestibular function tests have been used to evaluate vestibular symptoms among people living with HIV (PLWH). However, these tests are inconsistent due to poor sensitivity and specificity. This study attempts to identify sensitive and specific vestibular symptoms that may be useful in selecting appropriate HIV-positive adults for clinical vestibular function tests. Methods: Participants were enrolled from the Baltimore-Washington, DC, site of the Multicenter AIDS Cohort Study and the Washington, DC, site of the Women’s Interagency HIV Study. A total of 246 participants were evaluated using the Dix-Hallpike (DH) maneuver and the eyes closed, standing on foam (ECF) position in the Romberg test, and completed the Adult Balance and Dizziness Supplemental questionnaire of the 2008 National Health Interview Survey. The sensitivity and specificity were calculated using self-reported vestibular dysfunction from the questionnaire data compared with vestibular dysfunction determined by clinical testing. Results: Sixty participants (24.4%) reported vestibular dysfunction. The prevalence of abnormal tests was 40.8% for DH–any nystagmus, 1.5% for DH–classical nystagmus, 40.3% for DH–nonclassical nystagmus, 38.3% for gaze-evoked nystagmus, and 15.7% for Romberg ECF. Sensitivity of self-reported vestibular symptoms for all vestibular function tests reported ranged from 23.1% to 50.0%. These symptoms were moderately specific and ranged from 73.3% to 77.9%. Conclusions: Despite adequate specificity, the low sensitivity of self-reported symptoms of vestibular dysfunction were not useful to rule out a vestibular disorder in this sample of middle-aged PLWH. Therefore, clinical testing is needed to confirm the diagnosis of a vestibular disorder in the management of HIV disease.