The Vestibular System and Ageing

Can virtual reality replace conventional vestibular rehabilitation tools in multisensory balance exercises for vestibular disorders? A non-inferiority study

BACKGROUND

Vestibular rehabilitation uses multisensory balance exercises to optimize the integration and weighting of sensory inputs, including visual, vestibular, and proprioceptive signals. Head-mounted displays (HMDs) have emerged as a promising tool for these exercises, offering the ability to generate unreliable or conflicting visual stimuli, thereby enhancing vestibular and proprioceptive input weighting. This study aimed to determine whether a virtual reality (VR)-based rehabilitation program using HMDs is non-inferior to a conventional program employing an optokinetic stimulator and slaved environmental surround for multisensory balance exercises.

METHODS

Seventy-six participants with vestibular disorders were randomized into either the VR-based or conventional rehabilitation program for three weeks in a randomized controlled non-inferiority trial with blinded assessment. The non-inferiority margin was set at 5% of the control group's score. Both programs were multidisciplinary and included multisensory balance exercises designed to challenge sensory re-weighting. The primary outcome was the stability score, measured with eyes closed on an unstable platform using posturography, to evaluate postural control. Secondary outcomes included other variables from posturography, perceived disability assessed using the Dizziness Handicap Inventory (DHI), and tolerance to the multisensory balance exercises with unreliable or conflicting visual stimuli, assessed using the Simulator Sickness Questionnaire (SSQ).

RESULTS

The results showed that multisensory balance exercises with unreliable or conflicting visual stimuli were well tolerated in both groups, as indicated by low SSQ scores. Both rehabilitation programs led to significant pre-post improvements in postural control and perceived disability. However, the VR program did not meet the non-inferiority criterion compared to the conventional program. The primary outcome analysis revealed a difference of - 13.36 (95% CI - 29.84 to 3.11), with the lower bound of the confidence interval (- 29.84) falling below the non-inferiority margin of -2.01. Similarly, secondary outcomes, including other variables from posturography and the DHI, also failed to meet the non-inferiority criterion.

CONCLUSION

Although VR rehabilitation shows innovative potential for multisensory balance training, its effectiveness was not demonstrated to be non-inferior to the conventional approach. Therefore, we recommend considering it as a complementary tool rather than a primary device for vestibular rehabilitation. Further research is needed to enhance the efficacy of VR-based rehabilitation for vestibular disorders while maintaining its tolerance. Trial registration NCT03838562.

Age-related changes in the vestibulothalamic pathway: Association with balance ability and subjective visual vertical of vestibular function

INTRODUCTION

The thalamus regulates various sensory information to each related brain area. The vestibular nucleus transmits information of motor control to the thalamus regulating coordination function. The vestibulothalamic tract (VTT) is a neural pathway between the vestibular nucleus and thalamus that processes vestibular information for postural balance and spatial perception. Therefore, this study analyzed ipsilateral VTT to compare the neural pathway and the differences in vestibular and balance functions according to aging.

METHODS

Eleven elderly and 12 young healthy adults were recruited. This study measured subjective visual vertical (SVV) for vestibular function and body sway during one-leg standing. The ipsilateral VTT were reconstructed to investigate changes of neural pathway between two groups using diffusion tensor imaging.

RESULTS

Track volume of left and right VTTs was significantly more in the young healthy adults. In eyes-open (EO) condition during one-leg standing, the body sway demonstrated significant differences between two groups. In the eyes-closed (EC) condition, the degree of hip sway was decreased in the young healthy adults. In the EO condition, the body sway except for antero-posterior direction was significantly correlated with VTT. Meanwhile, in the EC condition, hip sway and all values of body sway were negatively correlated with VTT. In addition, the VTT revealed a negative correlation with SVV.

CONCLUSIONS

The tract volume of VTT and static balance decreased according to aging. The changes of VTT also affected verticality perception and static balance. Therefore, the study could be helpful in providing the data for patients with thalamus or vestibular injury.

Increased Homer Activity and NMJ Localization in the Vestibular Lesion het-/- Mouse soleus Muscle

We investigated the shuttling of Homer protein isoforms identified in soluble (cytosolic) vs. insoluble (membrane-cytoskeletal) fraction and Homer protein-protein interaction/activation in the deep postural calf soleus (SOL) and non-postural gastrocnemius (GAS) muscles of het-/- mice, i.e., mice with an autosomal recessive variant responsible for a vestibular disorder, in order to further elucidate a) the underlying mechanisms of disrupted vestibular system-derived modulation on skeletal muscle, and b) molecular signaling at respective neuromuscular synapses. Heterozygote mice muscles served as the control (CTR). An increase in Homer cross-linking capacity was present in the SOL muscle of het-/- mice as a compensatory mechanism for the altered vestibule system function. Indeed, in both fractions, different Homer immunoreactive bands were detectable, as were Homer monomers (~43-48 kDa), Homer dimers (~100 kDa), and several other Homer multimer bands (>150 kDA). The het-/- GAS particulate fraction showed no Homer dimers vs. SOL. The het-/- SOL soluble fraction showed a twofold increase (+117%, p ≤ 0.0004) in Homer dimers and multimers. Homer monomers were completely absent from the SOL independent of the animals studied, suggesting muscle-specific changes in Homer monomer vs. dimer expression in the postural SOL vs. the non-postural GAS muscles. A morphological assessment showed an increase (+14%, p ≤ 0.0001) in slow/type-I myofiber cross-sectional area in the SOL of het-/- vs. CTR mice. Homer subcellular immuno-localization at the neuromuscular junction (NMJ) showed an altered expression in the SOL of het-/-mice, whereas only not-significant changes were found for all Homer isoforms, as judged by RT-qPCR analysis. Thus, muscle-specific changes, myofiber properties, and neuromuscular signaling mechanisms share causal relationships, as highlighted by the variable subcellular Homer isoform expression at the instable NMJs of vestibular lesioned het-/- mice.

Evaluation of balance and executive function relationships in older individuals

BACKGROUND

Executive function is an important cognitive factor in gait and balance control. Weakening of balance system components and executive functions due to aging may affect walking and balance and increase the risk of falling.

AIMS

The present study aimed to investigate the relationship between balance and executive function in older individuals and the contributions of physical activity and depression to this relationship.

METHODS

A total of 84 healthy individuals aged 60 and over were included in the study. In the study, the Timed Up and Go Test (TUG), Mini Balance Evaluation Systems Test (Mini-BESTest), Digit Symbol Substitution Test (DSST), Trail Making Test A and B (TMT A and TMT B), Physical Activity Scale for the Elderly (PASE), and Geriatric Depression Scale (GDS) were applied.

RESULTS

The Mini-BESTest and TUG correlated with DSST, TMT A, and TMT B. GDS was correlated with TUG. PASE was correlated with Mini-BESTest and TUG. Executive functions differed according to education level; DSST, TMT B, and GDS were effective in fall history.

DISCUSSION

There was a significant relationship between balance and executive function. It was found that balance and walking speed increased as executive function skills increased. Depression and physical activity are associated with balance and gait speed.

CONCLUSIONS

Balance and executive functions are related to each other, and physical activity and depression contribute to this relationship. In order to protect against the negative effects of aging, cognitive and physical training can be performed to prevent balance and executive function declines.

Mandibular fractures in aged patients - Challenges in diagnosis

BACKGROUND/AIMS

Delayed treatment of a mandibular fracture can lead to complications. Therefore, early diagnosis is important. The aim of this study was to clarify the specific features of mandibular fractures in aged patients and the effect of age on possible missed diagnoses.

MATERIAL AND METHODS

Patients aged over 60 years with a recent mandibular fracture were included in the study. The outcome variable was a missed mandibular fracture during the patient's first assessment in the primary health care facility. Predictor variables were age group, categorized as older adults (aged ≥60 and <80 years), elders (aged >80 years), patient's age as a continuous variable and age sub-group divided into decades. Additional predictor variables were the patient's memory disease and injury associated with intracranial injury. Explanatory variables were gender, injury mechanism, type of mandibular facture, combined other facial fracture, edentulous mandible/maxilla/both, surgical treatment of the mandibular fracture, and scene of injury.

RESULTS

Mandibular fractures were missed in 20.0% of the 135 patients during their first healthcare assessment. Significant associations between missed fractures and age group, gender, fracture type, or injury mechanism were not found. By contrast, memory disorder (p = .02) and site of injury (p = .02) were significantly associated with missed fractures. Fractures were missed more frequently in patients who were in hospital or in a nursing home at the time of injury.

CONCLUSIONS

There is an increased risk of undiagnosed mandibular fractures in the aged population. Small injury force accidents may cause fractures in old and fragile individuals. Careful examination is necessary, especially in patients with memory disorder.

Dizziness in older persons at high risk of future hospitalization: prevalence, differences between those with and without dizziness, and effect of a proactive primary care intervention

Background

Dizziness is a common reason for seeking care, and frequently affects older persons. The aims were to determine the prevalence of dizziness in older persons at high risk of hospitalization, to compare subjects with and without dizziness, and to examine the effects on dizziness of a proactive primary care intervention in comparison with conventional care after one year.

Methods

Data were derived from a prospective multicentre clinical trial in persons aged 75 and older and at high risk of hospitalization. A baseline questionnaire included demographic data, use of aids, questions about everyday physical activity and exercise, pain (intensity, frequency, and duration), activities of daily living measured using the ADL Staircase, and health-related quality of life measured using the EQ-5D-3L vertical visual analogue scale. Both at baseline and after one year, subjects were asked about dizziness, and those with dizziness answered the Dizziness Handicap Inventory – Screening version. Subjects in the intervention group were evaluated by a primary care team and when needed proactive care plans were established. Groups were compared using the Mann Whitney U-test or chi-squared test.

Results

Of the 779 subjects, 493 (63%) experienced dizziness. Persons with dizziness differed regarding sex, homecare service, aids, activities of daily living, health-related quality of life, physical activity, and pain. The intervention did not significantly reduce the level of dizziness.

Conclusions

Dizziness is common in vulnerable older persons, and individuals with dizziness differ in several respects. Further studies are needed employing more dizziness-specific assessment and individually tailored interventions.

Trial registration

ClinicalTrials.gov 170608, ID: NCT03180606.

Age-Related Changes in the Cochlea and Vestibule: Shared Patterns and Processes

Both age-related hearing loss (ARHL) and age-related loss in vestibular function (ARVL) are prevalent conditions with deleterious consequences on the health and quality of life. Age-related changes in the inner ear are key contributors to both conditions. The auditory and vestibular systems rely on a shared sensory organ - the inner ear - and, like other sensory organs, the inner ear is susceptible to the effects of aging. Despite involvement of the same sensory structure, ARHL and ARVL are often considered separately. Insight essential for the development of improved diagnostics and treatments for both ARHL and ARVL can be gained by careful examination of their shared and unique pathophysiology in the auditory and vestibular end organs of the inner ear. To this end, this review begins by comparing the prevalence patterns of ARHL and ARVL. Next, the normal and age-related changes in the structure and function of the auditory and vestibular end organs are compared. Then, the contributions of various molecular mechanisms, notably inflammaging, oxidative stress, and genetic factors, are evaluated as possible common culprits that interrelate pathophysiology in the cochlea and vestibular end organs as part of ARHL and ARVL. A careful comparison of these changes reveals that the patterns of pathophysiology show similarities but also differences both between the cochlea and vestibular end organs and among the vestibular end organs. Future progress will depend on the development and application of new research strategies and the integrated investigation of ARHL and ARVL using both clinical and animal models.

Progress in protecting vestibular hair cells

Vestibular hair cells are mechanosensory receptors that are capable of detecting changes in head position and thereby allow animals to maintain their posture and coordinate their movement. Vestibular hair cells are susceptible to ototoxic drugs, aging, and genetic factors that can lead to permanent vestibular dysfunction. Vestibular dysfunction mainly results from the injury of hair cells, which are located in the vestibular sensory epithelium. This review summarizes the mechanisms of different factors causing vestibular hair cell damage and therapeutic strategies to protect vestibular hair cells.

Vestibular function modulates the impact of nGVS on postural control in older adults

Previous studies have reported an important relationship between increasing age, vestibular impairment, and increased risk of falls. Recently, noisy galvanic vestibular stimulation (nGVS) has been shown to improve postural control in older adults during and potentially following stimulation. However, this effect of nGVS in older adults has not been examined in interaction with the integrity of the vestibular function. We aimed at determining the effect of nGVS on postural control in older adults with and without vestibular impairment and examining the sustained effect of nGVS as compared with a sham stimulation. Thirty-six older adults were assigned to the nGVS group (n = 24) or the sham group (n = 12). In the nGVS group, 12 participants had normal vestibular function and 12 had vestibular impairment. Static postural control was assessed prior to stimulation, during stimulation, and immediately following 30 min of nGVS. Results showed that nGVS induced a significant improvement in sway velocity (P < 0.001) and path length (P < 0.001) compared with sham stimulation. Furthermore, nGVS induced a significantly greater improvement of sway velocity (P < 0.05) and path length (P < 0.05) in older adults with vestibular impairment compared with older adults with normal vestibular function. Improvements in sway velocity (P < 0.001) and path length (P < 0.001) induced by nGVS were sustained immediately following stimulation. These findings suggest that nGVS improves postural control in older adults, and that the effect of nGVS varies depending on the integrity of the vestibular function. Results also show that nGVS effect on postural control, compared with a sham stimulation, can be sustained after the end of stimulation.NEW & NOTEWORTHY The present study is the first study to investigate the impact of vestibular function on the improvement of postural control induced by nGVS in older adults and to compare the improvement of postural control of older adults with and without vestibular impairment. Our results also suggest that nGVS is beneficial for all older adults, and even more for those with a vestibular impairment. Therefore, it could be an approach to reduce falls.

Aging, Vestibular Function, and Balance: Proceedings of a National Institute on Aging/National Institute on Deafness and Other Communication Disorders Workshop

Balance impairment and falls are among the most prevalent and morbid conditions affecting older adults. A critical contributor to balance and gait function is the vestibular system; however, there remain substantial knowledge gaps regarding age-related vestibular loss and its contribution to balance impairment and falls in older adults. Given these knowledge gaps, the National Institute on Aging and the National Institute on Deafness and Other Communication Disorders convened a multidisciplinary workshop in April 2019 that brought together experts from a wide array of disciplines, such as vestibular physiology, neuroscience, movement science, rehabilitation, and geriatrics. The goal of the workshop was to identify key knowledge gaps on vestibular function and balance control in older adults and develop a research agenda to make substantial advancements in the field. This article provides a report of the proceedings of this workshop. Three key questions emerged from the workshop, specifically: (i) How does aging impact vestibular function?; (ii) How do we know what is the contribution of age-related vestibular impairment to an older adult's balance problem?; and more broadly, (iii) Can we develop a nosology of balance impairments in older adults that can guide clinical practice? For each of these key questions, the current knowledge is reviewed, and the critical knowledge gaps and research strategies to address them are discussed. This document outlines an ambitious 5- to 10-year research agenda for increasing knowledge related to vestibular impairment and balance control in older adults, with the ultimate goal of linking this knowledge to more effective treatment.