Role of vestibular adaptation in vestibular rehabilitation

Comparison of effects of Otago exercise program vs gaze stability exercise on balance and fear of fall in older adults: A randomized trial

BACKGROUND

Fall occurrences and the associated risk of injury are debilitating and major health concerns in the older population. Several interventions have been investigated and implemented to address the needs of balance impairments and to reduce the increased risk of falls. This study aimed to compare the effectiveness of the Otago exercise program (OEP) and gaze stability exercises (GSE) on balance and the risk of falls in older adults residing at an old age home facility.

METHODS

Thirty elderly participants were equally and randomly divided into 2 groups: Group OEP received the OEP, and group GSE received GSE for 8 weeks (thrice a week). In addition, both groups also performed core muscle-strengthening exercises. The outcome measures were the Berg balance scale (BBS) and the Fall efficacy scale-International (FES-I).

RESULTS

The interventions resulted in significant improvements (P < .001) in both outcome measures in both groups. The mean pretest BBS scores of groups OEP and GSE increased from 40.4 and 39.2 to the mean post-test scores of 48 and 45.2, respectively. Similarly, the mean pretest FES-I scores of groups OEP and GSE also improved from 39.47 and 40.4 to the mean post-test scores of 32.73 and 36.07. The between-group comparison showed greater improvement (P < .05) in OEP group in both variables.

CONCLUSIONS

OEP and GSE were found to be beneficial rehabilitation programs in improving balance and fear of falls in healthy older adults. However, the OEP was found to be a more effective intervention and may allow better balance and fall prevention improvements.

TRIAL REGISTRATION

The study has been registered in clinicaltrials.gov (ID: NCT05781776; on 23/03/2023).

[Structured ABEV Exercises for the Treatment of vestibular dysfunction]

INTRODUCTION

In addition to medication, the standard clinical treatment for vestibular vertigo primarily includes physical therapy in the form of regular exercises. Vertidisan is a future digital health application (DiGA) for structured dizziness therapy. Its content is multimodal and consists of Adaptive Balance and Eye Movements and Visual Stimulation (ABEV) exercises, which are expected to have an anti-vertigo effect through neural learning.

METHODS

A cohort study with 104 patients with intra-individual control was conducted to examine the clinical efficacy of solely 16 ABEV exercises for the treatment of peripheral vestibulopathies which are also used digitally in the future DiGA Vertidisan. Using the short version vertigo symptom scale short form1 vertigo and related symptoms (VSS-sf1-VER) of the vertigo-specific and validated VSS rating scale (Vertigo Symptom Scale) as the primary outcome variable, the vertigo scores before therapy (time T0) were compared with the corresponding data at the end of a period of 12-16 weeks (time T1).

RESULTS

Complete datasets on T0 and T1 were available for N=104 patients. The mean VSS-sf1-V score decreased from 3.80 (median 4, SD 0.47) to 0.92 (median 1, SD 1.19) from T0 to T1 (weeks 12-16). The result is statistically significant (p=0.001) and shows a high clinical effect size.

CONCLUSION

In summary, the analysis of the dizziness score shows a statistically and clinically significant reduction in dizziness through the use of the 16 ABEV exercises.

Compensatory strategies after an acute unilateral vestibulopathy: a prospective observational study

PURPOSE

In case of an acute unilateral vestibulopathy (UVP), compensatory strategies such as restoration and adaptation will lead to a decrease in intensity of the symptoms. Although measurements of compensatory strategies are available, currently, an overview taking the different strategies into account is lacking. The objectives of this study are to explore compensatory strategies and to investigate the association between compensatory strategies and patient characteristics.

METHODS

Restoration was objectified by the vestibulo-ocular reflex (VOR) gain on the video head impulse test, and adaptation-consisting of visual, multisensory, and behavioral substitution-was objectified by the Visual Vertigo Analog Scale (VVAS), Antwerp Vestibular Compensation Index (AVeCI), and Perez and Rey score (PR score), respectively. Adequate restoration and adaptation levels were interpreted as follows: VOR gain > 0.80, VVAS ≤ 40%, AVeCI > 0 and PR score ≤ 55.

RESULTS

Sixty-two UVP patients, 34 men and 28 women, were included with an average age of 52.1 ± 17.3 years. At 10.5 ± 1.4 weeks after onset, 41.9% of the UVP patients reached adequate restoration levels and 58.1-86.9% reached adequate adaptation levels. Furthermore, significant associations were found between (1) restoration status and UVP etiology [Odds Ratio (OR) with 95% CI: 4.167 {1.353;12.828}] and balance performance (OR: 4.400 {1.258;15.386}), (2) visual sensory substitution status and perceived handicap (OR: 8.144 {1.644;40.395}), anxiety (OR: 10.000 {1.579;63.316}) and depression (OR: 16.667 {2.726;101.896}), and (3) behavioral substitution status and balance performance (OR: 4.143 {1.341;12.798}).

CONCLUSION

UVP patients with adequate compensatory strategies presented with better balance performance, lower perceived handicap, and lower anxiety and depression scores.

Bilateral vestibulopathy: a clinical update and proposed diagnostic algorithm

Bilateral vestibulopathy (BVP) is characterized by its heterogeneous and chronic nature with various clinical presentations and multiple etiologies. This current narrative review reflects on the main insights and developments regarding clinical presentation. In addition, it proposes a new diagnostic algorithm, and describes available and potential future therapeutic modalities.

Supervised multicomponent exercise as an adjuvant program for people with unilateral and/or bilateral chronic vestibular hypofunction: EXERVEST study protocol

Background

Unilateral and bilateral peripheral vestibular hypofunction (UVH and BVH) often complains of dizziness, gaze, and balance disturbances. There is a lack of evidence on exercise intervention in UVH and BVH patients. To investigate the effect of an eight-week supervised multicomponent exercise program in people suffering from UVH or BVH in comparison with a control group doing conventional vestibular rehabilitation at home.

Methods

This longitudinal, controlled, randomized, prospective, single-blinded, two-arm, parallel intervention study will include 66 adults (≥18 years old) with chronic UVH or BVH. Participants will be randomly assigned to an exercise intervention group or an attention control group. Participants will be assessed at baseline, after a two-month intervention period, and after a six-month follow-up. The primary variable will be the balance, measured by the dynamic posturography sensory organization test and the Modified Dynamic Gait Index test. Secondary outcome variables will include cardiorespiratory fitness (peak cardiopulmonary exercise test), body composition (bioimpedance and anthropometric variables), physical activity level and sleep quality (accelerometry), health-related quality of life (Dizziness Handicap Inventory questionnaire), emotional state (Beck Depression and Anxiety Inventory questionnaires), and blood pressure monitoring.

Discussion

This study will try to answer whether in people with UVH/BVH, an adjuvant program of multicomponent exercise will help the prognosis of this population.

Trial registration

ClinicalTrials.gov, identifier [NCT05192564]. Verification date: April 2023.

Compensatory saccade in the vestibular impaired monkey

Introduction

Loss of the vestibulo-ocular reflex (VOR) affects visual acuity during head movements. Patients with unilateral and bilateral vestibular deficits often use saccadic eye movements to compensate for an inadequate VOR. Two types of compensatory saccades have been distinguished, covert saccades and overt saccades. Covert saccades occur during head rotation, whereas overt saccades occur after the head has stopped moving. The generation of covert saccades is part of a central vestibular compensation process that improves visual acuity and suppresses oscillopsia. Understanding the covert saccade mechanism may facilitate vestibular rehabilitation strategies that can improve the patient's quality of life. To understand the brain mechanisms underlying covert saccades at the neural level, studies in an animal model are necessary. In this study, we employed non-human primates whose vestibular end organs are injured.

Methods

We examined eye movement during the head-impulse test, which is a clinical test to evaluate the vestibulo-ocular reflex. During this test, the monkeys are required to fixate on a target and the head is rapidly and unexpectedly rotated to stimulate the horizontal semi-circular canals.

Results

Similar to human subjects, monkeys made compensatory saccades. We compared these saccades with catch-up saccades following a moving target that simulates the visual conditions during the head impulse test. The shortest latency of the catch-up saccades was 250 ms, which indicates that it requires at least 250 ms to induce saccades by a visual signal. The latency of some compensatory saccades is shorter than 250 ms during the head impulse test, suggesting that such short latency compensatory saccades were not induced visually. The peak velocity of the short latency saccades was significantly lower than that of longer latency saccades. The peak velocity of these longer latency saccades was closer to that of visually guided saccades induced by a stepping target.

Conclusion

These results are consistent with studies in human patients. Thus, this study demonstrates, for the first time, compensatory covert saccades in vestibular impaired monkeys.

Vestibular rehabilitation potential of commercially available virtual reality video games

BACKGROUND

Peripheral vestibular disorders affect 2.8-6.5% of people. Standard treatment is vestibular rehabilitation therapy, and virtual reality (VR) could improve outcomes. The objective of this study was to identify the commercially available VR video game that is most congruent to vestibular rehabilitation therapy.

METHODS

A term search "virtual reality racing" was performed on the App Store in March 2022. Results were screened for free point-of-view racing games compatible with Android and iOS devices. An investigator was filmed playing each game and videos were distributed to 237 physiotherapists. Physiotherapists completed a survey of 5-point Likert scale questions that assessed the video games vestibular rehabilitation potential. Survey responses were analyzed using Friedman Two-Way ANOVA (alpha = 0.05) and paired samples sign test with Bonferroni correction.

RESULTS

The search yielded 58 games, 4 were included. Forty physiotherapists participated. VR Tunnel Race (VRTR) and VR Real World Bike Racing (VRWBR) had the greatest vestibular rehabilitation potential (median global scores = 18.00). VRTR replicated habituation exercises significantly (p < 0.001) better than Derby VR, and VRWBR replicated physiotherapist-prescribed exercises significantly (p < 0.001) better than VR X-Racer. There were no discernable significant differences between VRWBR and VRTR.

CONCLUSIONS

VRTR and VRWBR are the most congruent VR games to standard vestibular rehabilitation. VRWBR is preferable to VRTR with respect to ease of use and the ability to alter the amount of optokinetic stimulation. Prospective studies are needed to confirm the efficacy of these videos games and to determine if they could be used as solitary treatments.

TRIAL REGISTRATION

Not applicable.

Automatic ML-based vestibular gait classification: examining the effects of IMU placement and gait task selection

BACKGROUND

Vestibular deficits can impair an individual's ability to maintain postural and/or gaze stability. Characterizing gait abnormalities among individuals affected by vestibular deficits could help identify patients at high risk of falling and inform rehabilitation programs. Commonly used gait assessment tools rely on simple measures such as timing and visual observations of path deviations by clinicians. These simple measures may not capture subtle changes in gait kinematics. Therefore, we investigated the use of wearable inertial measurement units (IMUs) and machine learning (ML) approaches to automatically discriminate between gait patterns of individuals with vestibular deficits and age-matched controls. The goal of this study was to examine the effects of IMU placement and gait task selection on the performance of automatic vestibular gait classifiers.

METHODS

Thirty study participants (15 with vestibular deficits and 15 age-matched controls) participated in a single-session gait study during which they performed seven gait tasks while donning a full-body set of IMUs. Classification performance was reported in terms of area under the receiver operating characteristic curve (AUROC) scores for Random Forest models trained on data from each IMU placement for each gait task.

RESULTS

Several models were able to classify vestibular gait better than random (AUROC > 0.5), but their performance varied according to IMU placement and gait task selection. Results indicated that a single IMU placed on the left arm when walking with eyes closed resulted in the highest AUROC score for a single IMU (AUROC = 0.88 [0.84, 0.89]). Feature permutation results indicated that participants with vestibular deficits reduced their arm swing compared to age-matched controls while they walked with eyes closed.

CONCLUSIONS

These findings highlighted differences in upper extremity kinematics during walking with eyes closed that were characteristic of vestibular deficits and showed evidence of the discriminative ability of IMU-based automated screening for vestibular deficits. Further research should explore the mechanisms driving arm swing differences in the vestibular population.

Unidirectional Vertical Vestibuloocular Reflex Adaptation in Humans Using 1D and 2D Scenes

HYPOTHESIS

The vertical vestibuloocular reflex (VOR) in response to pitch head impulses can be optimally trained to increase in one direction using a two-dimensional (2D) visual training target with minimal effect on the horizontal VOR.

BACKGROUND

We modified the incremental VOR adaptation (IVA) technique, shown to increase the horizontal VOR in patients with vestibular hypofunction, to drive vertical VOR adaptation in healthy control subjects.

METHODS

We measured the horizontal and vertical active (self-generated) and passive (imposed) head impulse VOR gains (eye velocity/head velocity) before and after 15 minutes of unidirectional downward IVA training. IVA training consisted of two sessions, one using a single-dot one-dimensional (1D) target, the other a grid-of-dots 2D target.

RESULTS

The downward head impulse VOR gain significantly increased because of training by 13.3%, whereas the upward VOR gain did not change. The addition of extraretinal (2D) feedback did not result in greater adaptation, i.e., 1D and 2D gain increases were 15.5% and 10.6%, respectively. The vertical VOR gain increase resulted in a 3.2% decrease in horizontal VOR gain.

CONCLUSION

This preliminary study is the first to show that physiologically relevant (high frequency) unidirectional increases in vertical VOR gain are possible with just 15 minutes of training. This study sets the basis for future clinical trials examining vertical IVA training in patients, which may provide the first practical rehabilitation treatment to functionally improve the vertical VOR.

The clinical course of vestibular neuritis from the point of view of the ocular vestibular evoked myogenic potential

Background

Studying otolith functions after unilateral vestibular neuritis using ocular vestibular-evoked myogenic potentials and subjective visual vertical tests could give different results.

Method

A total of 39 patients underwent a vestibular assessment that included the Dizziness Handicap Inventory and horizontal and vertical semicircular canal function testing with video head impulse testing, ocular vestibular-evoked myogenic potential testing, cervical vestibular-evoked myogenic potentials and subjective visual vertical testing.

Results

All patients showed a significant alteration (asymmetry ratio more than 40 per cent) for ocular vestibular-evoked myogenic potentials as well as for subjective visual vertical testing (more than −2° to more than +2°) during the acute phase, whereas after 72 hours from the acute vertigo attack normal values (asymmetry ratio less than 40 per cent) were found in 6 out of 39 patients for ocular vestibular-evoked myogenic potentials and 36 out of 39 for the subjective visual vertical (less than −2° to less than +2°).

Conclusion

Ocular vestibular-evoked myogenic potentials are the most suitable test to evaluate otolith functions in patients with unilateral vestibular neuritis in the acute and sub-acute phase.

Effects of customized vestibular rehabilitation plus canalith repositioning maneuver on gait and balance in adults with Benign Paroxysmal Positional Vertigo: A Randomized Controlled Trial

BACKGROUND

Adults with unilateral posterior canal benign paroxysmal positional vertigo (BPPV) may continue to present with residual dizziness and balance impairments after the canalith repositioning maneuver (CRM). Customized Vestibular rehabilitation (VR) in addition to the standard CRM may improve postural control in adults with BPPV. However, the effectiveness of this intervention for improving dyanmic gait measures in adults with BPPV is unknown.

OBJECTIVE

We aimed to determine the effectiveness of customized VR in addition to the standard CRM on dynamic gait measures among adults with unilateral posterior canal BPPV.

METHODS

In this double blind, randomized controlled trial, 28 adults with BPPV were randomized to either control (n = 14, age: 54.36±8.55) or experimental (n = 14, age: 50.71±9.88) groups. The experimental and control groups received customized VR plus standard CRM for six weeks and standard CRM for two weeks respectively. Dynamic gait measures (duration of a complete gait cycle, stride velocity, turning duration and number of steps while turning) were recorded using a portable mobility sensor (iTUG) at baseline, week 4 and 6. A mixed model ANOVA was used to estimate the main effects of the interventions.

RESULTS

During walking, a group effect was demonstrated on gait duration, stride velocity, turning duration and number of steps while turning (p <  0.05).

CONCLUSIONS

Six weeks of customized VR performed in addition to the standard CRM was more effective than the standard CRM alone in improving balance and gait in adults with posterior canal BPPV. (252 words).

Vestibular Rehabilitation after Vestibulopathy Focusing on the Application of Virtual Reality

Human postural control is regulated by the vestibular, somatosensory, and visual systems. These types of sensory information are integrated in the central nervous system to ascertain the body’s position in space. Proper functioning of the vestibular, somatosensory, and visual senses is necessary for the body to maintain equilibrium. Bilateral vestibulopathy (BVP) is a condition in which bilateral peripheral vestibular function is reduced. Its treatment includes vestibular rehabilitation (VeR), balance training, counseling, treating the underlying cause, and avoiding further damage to the vestibular system. As VeR is often tedious for patients, patient motivation is required or patients may drop out of the program. To solve this problem, in recent years, there have been increasing reports of VeR using virtual reality, which increases vestibulo-ocular reflex gain and decreased dizziness by inducing adaptation. In this review, we discuss VeR, particularly for BVP, and VeR using virtual reality.

Systematic Review and Meta-analysis: Effectiveness of Corticosteroids in Treating Adults With Acute Vestibular Neuritis

OBJECTIVES

To determine whether steroids are effective in treating adults with acute vestibular neuritis.

DATA SOURCES

PubMed, Embase, CINAHL, Cochrane CENTRAL, Web of Science, CAB Abstract, ICTRP, LILACS, PEDRO, ClinicalTrials.Gov, Google Scholar, NARIC, and OT Seeker.

REVIEW METHODS

A systematic review was undertaken for articles reporting subjective and/or objective outcomes of corticosteroids in adults with acute vestibular neuritis between December 2010 and October 2019. Reports of patient recovery from clinical vestibular outcomes at various time points and adverse effects from corticosteroids were of interest. Statistical analysis included qualitative and quantitative assessments. A limited meta-analysis of the data was performed through a random effects model.

RESULTS

Eight studies met the criteria, and 6 were included in the meta-analysis. No significant differences between the groups (corticosteroid vs placebo, corticosteroid vs vestibular exercise, or corticosteroid vs combination of vestibular exercise and corticosteroid) were reported in the proportion of patients with complete recovery at 1, 6, and 12 months. The corticosteroid group had significantly better caloric recover at 1 month (95% CI, -16.33 to -0.32); however, there was no significant difference to the overall effect between the groups across 12 months. Subjective recovery did not differ between the groups. Five of the 8 studies reported on adverse effects from corticosteroids.

CONCLUSION

There is insufficient evidence to support the use of corticosteroids in managing acute vestibular neuritis in adults. At present, corticosteroids appear to have short-term benefits in canal paresis but no long-term benefits in canal paresis and symptomatic recovery. Future studies should consider including a wider variety of clinical vestibular tests and frequent acute follow-ups to monitor the effects of corticosteroids.

Effects of using cane and vestibular rehabilitation on the walking function in elderly patients with dizziness

OBJECTIVE

Adults over the age of 65 years with balance disorders are at about twice the risk of falls, compared with those without balance disorders. Falls contribute to about 74% of the proximal femoral fractures commonly seen in the elderly. Since balance disorders are more prevalent in older adults than in younger adults, it is important to deal with balance disorders in older adults to prevent falls and the resulting deterioration in their ADL (activity of daily living). In this study, we investigated the effects of vestibular rehabilitation (VR) and cane use on improving gait and balance in patients aged over 65 years with balance disorder.

METHODS

Patients aged over 65 years presenting to the Department of Otolaryngology at St. Marianna University School of Medicine between July 1 and November 1, 2018, with symptoms of dizziness for ≥ 3 months and a Japanese translation of the Dizziness Handicap Inventory score of ≥ 26 were included in the study. We quantitatively analyzed their gait before and after VR, and with and without the use of a cane.

RESULTS

A total of 21 patients participated in the study (14 women; mean age 73.9 ± 6.9 years). Before VR, using a cane made no difference to step length or walking speed. After VR, using a cane increased step length from 50.5 cm (95% confidence interval [CI], 47.4-53.7 cm) to 52.0 cm (95% CI, 48.9-55.1 cm) (p = 0.039). There was no change in walking speed. A comparison of walking assessment results while using a cane before and after VR showed that step length increased from 49.9 cm (95% CI, 46.6-53.2 cm) to 52.0 cm (95% CI, 48.9-55.1 cm) (p = 0.005), and walking speed increased from 90.5 cm/s (95% CI, 82.7-98.4 cm/s) to 96.1 cm/s (95% CI, 88.3-103.9 cm/s) (p = 0.005).

CONCLUSIONS

Walking speed and step length with the use of a cane significantly improved following VR. VR and cane use may act synergistically to improve walking.

Efficacy and Comparison of Vestibular Rehabilitation Exercises on Quality of Life in Patients with Vestibular Disorders

Vertigo is the sensation of spinning or having one's surroundings spin about them. It represents about 25% of cases of occurrences of dizziness Yardley et al. (Br J Gen Pract 48(429):1131-1135, 1998). About 40% patients have peripheral vestibular dysfunction (Neuhauser in Curr Opin Neurol 20:40-46, 2007). Quality of life (QOL) is significantly impaired by vertigo (Patatas et al. in Braz J Otorhinolaryngol 75:387-394, 2009). To study the effect and compare vestibular exercises on QOL in patients with vestibular disorders. 120 individuals with vestibular disorders like acoustic neuroma, vestibular neuritis, labyrinthitis, Meniere's disease, vestibulopathy, ISSNHL and ototoxicity were included. Four groups adaptation exercises, habituation exercises, substitution exercises, and combined exercises were formed and 30 individuals were selected in each group randomly. Vestibular activities and participation (VAP) was administered before and after exercises to fulfill the aim. VAP Scale results revealed significant difference between pre and post treatment score in all groups, suggestive of positive effect on QOL in patients with vestibular disorders. Improvements in VAP Score between all groups were compared and significant difference was observed. Combined exercises group found to be best out of 4 exercises group.

Human Vestibulo-Ocular Reflex Adaptation Reduces when Training Demand Variability Increases

One component of vestibular rehabilitation in patients with vestibulo-ocular reflex (VOR) hypofunction is gaze-stabilizing exercises that seek to increase (adapt) the VOR response. These prescribed home-based exercises are performed by the patient and thus their use/training is inherently variable. We sought to determine whether this variability affected VOR adaptation in ten healthy controls (× 2 training only) and ten patients with unilateral vestibular hypofunction (× 1 and × 2 training). During × 1 training, patients actively (self-generated, predictable) move their head sinusoidally while viewing a stationary fixation target; for × 2 training, they moved their outstretched hand anti-phase with their head rotation while attempting to view a handheld target. We defined the latter as manual × 2 training because the subject manually controls the target. In this study, head rotation frequency during training incrementally increased 0.5-2 Hz over 20 min. Active and passive (imposed, unpredictable) sinusoidal (1.3-Hz rotations) and head impulse VOR gains were measured before and after training. We show that for controls, manual × 2 training resulted in significant sinusoidal and impulse VOR adaptation of ~ 6 % and ~ 3 %, respectively, though this was ~two-thirds lower than increases after computer-controlled × 2 training (non-variable) reported in a prior study. In contrast, for patients, there was an increase in impulse but not sinusoidal VOR response after a single session of manual × 2 training. Patients had more than double the variability in VOR demand during manual × 2 training compared to controls, which could explain why adaptation was not significant in patients. Our data suggest that the clinical × 1 gaze-stabilizing exercise is a weak stimulus for VOR adaptation.

The instantaneous training demand drives vestibulo-ocular reflex adaptation

The vestibulo-ocular reflex (VOR) maintains stable vision during rapid head rotations by rotating the eyes in the opposite direction to the head. The latency between onset of the head rotation and onset of the eye rotation is 5-8 ms in healthy humans. However, VOR latency can be 3-4 times larger in patients treated with intra-tympanic gentamicin. A prior study showed that latency can be trained with head rotations at 0.2 Hz. We sought to determine how the VOR is affected when a delay between vestibular and visual stimuli is added during adaptation training with high-frequency head rotations (impulses), where the VOR is the main vision-stabilizing system. Using a variant of the incremental VOR adaptation technique, the delay between head rotation onset and movement onset of a visual target was gradually increased. With this training, the instantaneous VOR gain demand (= target/head velocity) varied from less than unity to greater than unity during each head impulse, albeit in a consistent and repeatable way. We measured the active and passive VOR gain and latency before and after VOR adaptation training in healthy normal subjects. There was no significant change in VOR latency across subjects; however, there was a significant decrease in VOR gain of - 6.0 ± 4.5%. These data suggest that during high-frequency head rotations delay/latency is interpreted as a changing instantaneous VOR gain demand. Although the gain demand in this study had a complex trajectory, adaptation was evident with the VOR seeming to use an average of the instantaneous gain demand.

Convergence Vestibulo-ocular Reflex in Unilateral Vestibular Hypofunction: Behavioral Evidence in Support of a Novel Gaze Stability Exercise

BACKGROUND AND PURPOSE

Convergence of the eyes during head rotation increases the gain (eye velocity/head velocity) of the vestibulo-ocular reflex (VOR). We sought to know whether convergence would increase the VOR gain (mean + SD) in unilateral vestibular hypofunction (UVH).

METHODS

Vestibulo-ocular reflex gain during ipsi- and contralesional horizontal head rotation at near (15 cm) and far (150 cm) targets was measured in 22 subjects with UVH and 12 healthy controls. Retinal slip was estimated (retinal slip index [RSI]) as the difference between ideal VOR gain (no retinal slip) and the actual VOR gain.

RESULTS

Convergence did not significantly enhance VOR gain for ipsilesional rotation (mean difference, 0.04; 95% confidence interval [CI], -0.01 to 0.09), near viewing (0.77 ± 0.34) versus far viewing (0.72 ± 0.29), yet the VOR gain during contralesional rotation was greater for near viewing (1.20 ± 0.23) than for far viewing (0.97 ± 0.21; mean difference, 0.23; 95% CI, 0.13-0.32). In the 36% of subjects with recovery of their ipsilesional VOR gain, the vergence effect trended to recover (far VOR gain: 1.06 ± 0.17 vs near VOR gain 1.16 ± 0.21; mean difference, 0.10; 95% CI, -0.02 to 0.22). Ipsilesional head rotation induced greater retinal slip for near (RSI = 0.90 ± 0.34) targets than for far targets (RSI = 0.35 ± 0.29; mean difference, 0.56; 95% CI, 0.51-0.61).

DISCUSSION AND CONCLUSIONS

The convergence-mediated VOR gain enhancement is preserved during contralesional but impaired during ipsilesional head rotation. Recovery of ipsilesional passive VOR gain does not equate to restored convergence enhancement, although it did increase ∼10%. These data suggest head motion viewing near targets will increase retinal slip, which warrants consideration as a gaze stability exercise for subjects with UVH.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A325).

Development of a Computerized Device for Evaluating Vestibular Function in Locomotion: A New Evaluation Tool of Vestibular Hypofunction

To evaluate vestibular function in the clinic, current assessments are applied under static conditions, such as with the subject in a sitting or supine position. Considering the complexities of daily activities, the combination of dynamic activities, dynamic visual acuity (DVA) and postural control could produce an evaluation that better reflects vestibular function in daily activities.

Objective: To develop a novel sensor-based system to investigate DVA, walking trajectory, head and trunk movements and the chest-pelvis rotation ratio during forward and backward overground walking in both healthy individuals and patients with vestibular hypofunction.

Methods: Fifteen healthy subjects and 7 patients with bilateral vestibular hypofunction (BVH) were recruited for this study. Inertial measurement units were placed on each subject's head and torso. Each subject walked forward and backward for 5 m twice with 2 Hz head yaw. Our experiment comprised 2 stages. In stage 1, we measured forward (FW), backward (BW), and medial-lateral (MLW) walking trajectories; head and trunk movements; and the chest-pelvis rotation ratio. In stage 2, we measured standing and locomotion DVA (loDVA). Using Mann–Whitney U-test, we compared the abovementioned parameters between the 2 groups.

Results: Patients exhibited an in-phase chest/pelvis reciprocal rotation ratio only in FW. The walking trajectory deviation, calculated by normalizing the summation of medial-lateral swaying with 1/2 body height (%), was significantly larger (FW mean ± standard deviation: 20.4 ± 7.1% (median (M)/interquartile range (IQR): 19.3/14.4–25.2)in healthy vs. 43.9 ± 27. 3% (M/IQR: 36.9/21.3–56.9) in patients, p = 0.020)/(BW mean ± standard deviation: 19.2 ± 11.5% (M/IQR: 13.6/10.4–25.3) in healthy vs. 29.3 ± 6.4% (M/IQR: 27.7/26.5–34.4) in patients, p = 0.026), and the walking DVA was also significantly higher (LogMAR score in the patient group [FW LogMAR: rightDVA: mean ± standard deviation:0.127 ± 0.081 (M/IQR: 0.127/0.036–0.159) in healthy vs. 0.243 ± 0.101 (M/IQR: 0.247/0.143–0.337) in patients (p = 0.013) and leftDVA: 0.136 ± 0.096 (M/IQR: 0.127/0.036–0.176) in healthy vs. 0.258 ± 0.092 (M/IQR: 0.247/0.176–0.301) in patients (p = 0.016); BW LogMAR: rightDVA: mean ± standard deviation: 0.162 ± 0.097 (M/IQR: 0.159/0.097–0.273) in healthy vs. 0.281 ± 0.130 (M/IQR: 0.273/0.176–0.418) in patients(p = 0.047) and leftDVA: 0.156 ± 0.101 (M/IQR: 0.159/0.097–0.198) in healthy vs. 0.298 ± 0.153 (M/IQR: 0.2730/0.159–0.484) in patients (p = 0.038)].

Conclusions: Our sensor-based vestibular evaluation system provided a more functionally relevant assessment for the identification of BVH patients.

Vestibular Schwannoma Tumor Size Is Associated With Acute Vestibular Symptoms After Gamma Knife Therapy

OBJECTIVE

To assess how pretreatment vestibular schwannoma (VS) tumor characteristics are associated with vestibular symptoms after gamma knife (GK) surgery.

STUDY DESIGN

Retrospective chart review of patients undergoing GK treatment for VS at our institution from 2005 to 2018.

SETTING

Academic tertiary referral center.

PATIENTS

Patients receiving primary GK surgery for vestibular schwannomas with at least 6 months of follow up. Patients with neurofibromatosis 2 or previous surgery were excluded.

MAIN OUTCOME MEASURES

The presence of posttreatment vestibular symptoms within 6 months after GK. Clinical records were assessed for pretreatment tumor, patient, and treatment characteristics that impacted posttreatment symptoms.

RESULTS

All patients received radiation doses between 12 and 13 Gy. Of 115 patients, the average age was 60. Thirty-seven (32%) patients developed vestibular symptoms within 6 months post-GK, and 18 patients were referred for vestibular rehabilitation. Ten of 13 patients undergoing vestibular rehabilitation reported improvement. Overall, 112 patients had tumor measurements. Pretreatment tumors were significantly smaller for patients with acute vestibular symptoms (mean 1.43 cm versus 1.71 cm, p = 0.007). On multivariate analysis, smaller tumor size (p = 0.009, odds ratio [OR] = 0.29, 95% confidence interval [CI] [0.12-0.73]) was significantly associated with vestibular symptoms within 6 months of GK. Patients with tumors less than 1.6 cm were more likely to receive referrals for vestibular rehabilitation within 6 months posttreatment (25% versus 9.4%, p = 0.026, OR = 3.22, 95% CI [1.00, 11.32]).

CONCLUSIONS

Smaller vestibular schwannomas were significantly associated with higher rates of post-GK vestibular symptoms. Pretreatment tumor size may be used to counsel patients on the likelihood of post-GK vestibular symptoms and vestibular rehabilitation.

Improvement After Vestibular Rehabilitation Not Explained by Improved Passive VOR Gain

Gaze stability exercises are a critical component of vestibular rehabilitation for individuals with vestibular hypofunction and many studies reveal the rehabilitation improves functional performance. However, few studies have examined the vestibular physiologic mechanisms (semicircular canal; otolith) responsible for such recovery after patients with vestibular hypofunction complete gaze and gait stability exercises. The purpose of this study was to compare behavioral outcome measures (i.e., visual acuity during head rotation) with physiological measures (i.e., gain of the vestibulo-ocular reflex) of gaze stability following a progressive vestibular rehabilitation program in patients following unilateral vestibular deafferentation surgery (UVD). We recruited n = 43 patients (n = 18 female, mean 52 ± 13 years, range 23-80 years) after unilateral deafferentation from vestibular schwannoma; n = 38 (25 female, mean 46.9 ± 15.9 years, range 22-77 years) age-matched healthy controls for dynamic visual acuity testing, and another n = 28 (14 female, age 45 ± 17, range 20-77 years) healthy controls for video head impulse testing. Data presented is from n = 19 patients (14 female, mean 48.9 ± 14.7 years) with UVD who completed a baseline assessment ~6 weeks after surgery, 5 weeks of vestibular physical therapy and a final measurement. As a group, subjective and fall risk measures improved with a meaningful clinical relevance. Dynamic visual acuity (DVA) during active head rotation improved [mean ipsilesional 38.57% ± 26.32 (n = 15/19)]; mean contralesional 39.96% ± 22.62 (n = 12/19), though not uniformly. However, as a group passive yaw VOR gain (mean ipsilesional pre 0.44 ± 0.18 vs. post 0.44 ± 0.15; mean contralesional pre 0.81 ± 0.19 vs. post 0.85 ± 0.09) did not show any change (p ≥ 0.4) after rehabilitation. The velocity of the overt compensatory saccades during ipsilesional head impulses were reduced after rehabilitation; no other metric of oculomotor function changed (p ≥ 0.4). Preserved utricular function was correlated with improved yaw DVA and preserved saccular function was correlated with improved pitch DVA. Our results suggest that 5 weeks of vestibular rehabilitation using gaze and gait stability exercises improves both subjective and behavioral performance despite absent change in VOR gain in a majority of patients, and that residual otolith function appears correlated with such change.

Vestibular training promotes adaptation of multisensory integration in postural control

BACKGROUND

Postural stability depends on the integration of the multisensory system to produce motor outputs. When visual and somatosensory input is reliable, this reduces reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction. Training one or more of the three sensory systems through vestibular habituation and adaptation can alter sensory weighting and change postural behavior.

AIM

The purpose of this study was to assess sensory reweighting of postural control processing after combined vestibular activation with voluntary weight shift training in healthy adults.

METHODS

Thirty-three healthy individuals (18-35 y.o.) were randomly assigned to one of three groups: No training (control), visual feedback weight shift training (WST) coupled with an active horizontal headshake (HS) activity to elicit a vestibular perturbation, or the same WST without HS (NoHS). Training was performed 2x/day, every other day (M, W, F), totaling six sessions. Pre- and post- assessments on the Sensory Organization Test (SOT) were performed. Separate between- and within- repeated measures ANOVAs were used to analyze the six SOT equilibrium scores, composite scores, sensory ratios and center of pressure (COP) variables by comparing baseline to post-training. Alpha level was set at p < .05.

RESULTS

There was a significant group x session x condition change (p = .012) in the COP multiscale entropy (MSE) velocity sway in the HS group during SOT conditions 5 and 6. Similarly, COP medio-lateral standard deviation sway (ML Std) showed group x session x visual condition (p = .028), due to HS in condition 6 relative to other two groups.

CONCLUSION

Postural training can alter sensory organization after a visual feedback-vestibular activation training protocol, suggesting a possible sensory reweighting through vestibular adaptation and/or habituation.

SIGNIFICANCE

Translating these findings into a vestibular-impaired population can stimulate the design of a rehabilitation balance protocol.

Human vestibulo-ocular reflex adaptation is frequency selective

The vestibulo-ocular reflex (VOR) is the only system that maintains stable vision during rapid head rotations. The VOR gain (eye/head velocity) can be trained to increase using a vestibular-visual mismatch stimulus. We sought to determine whether low-frequency (sinusoidal) head rotation during training leads to changes in the VOR during high-frequency head rotation testing, where the VOR is more physiologically relevant. We tested eight normal subjects over three sessions. For training protocol 1, subjects performed active sinusoidal head rotations at 1.3 Hz while tracking a laser target, whose velocity incrementally increased relative to head velocity so that the VOR gain required to stabilize the target went from 1.1 to 2 over 15 min. Protocol 2 was the same as protocol 1, except that head rotations were at 0.5 Hz. For protocol 3, head rotation frequency incrementally increased from 0.5 to 2 Hz over 15 min, while the VOR gain required to stabilize the target was kept at 2. We measured the active and passive, sinusoidal (1.3Hz) and head impulse VOR gains before and after each protocol. Sinusoidal and head impulse VOR gains increased in protocols 1 and 3; however, although the sinusoidal VOR gain increase was ~20%, the related head impulse gain increase was only ~10%. Protocol 2 resulted in no-gain adaptation. These data show human VOR adaptation is frequency selective, suggesting that if one seeks to increase the higher-frequency VOR response, i.e., where it is physiologically most relevant, then higher-frequency head movements are required during training, e.g., head impulses.NEW & NOTEWORTHY This study shows that human vestibulo-ocular reflex adaptation is frequency selective at frequencies >0.3 Hz. The VOR in response to mid- (1.3 Hz) and high-frequency (impulse) head rotations were measured before and after mid-frequency sinusoidal VOR adaptation training, revealing that the mid-frequency gain change was higher than high-frequency gain change. Thus, if one seeks to increase the higher-frequency VOR response, where it is physiologically most relevant, then higher-frequency head movements are required during training.

Differences in postural stability and dynamic visual acuity among healthy young adults in relation to sports activity: a cross sectional study

[Purpose] Sports activity has been shown to improve postural stability and vestibular function in healthy older adults. The hypothesis was that healthy young adults undertaking sports activity will also have better postural stability and vestibular function compared with healthy young adults who do not undertake sports activity. The purpose of this study was to investigate the differences in postural stability and vestibular function between healthy young adults who undertake sports activity and those who do not undertake such activity. [Participants and Methods] Thirty-nine healthy young adults were recruited and divided into sports and non-sports groups on the basis of their response to a questionnaire concerning regular participation in sports activities over the past 12 months. In both groups, postural stability was measured during quiet standing and standing during head rotation, and dynamic visual acuity was assessed during head rotation. [Results] The results showed significant differences in postural stability during head rotation and dynamic visual acuity between the two groups, whereas no significant differences were found in postural stability during quiet standing. [Conclusion] The results suggest that healthy young adults who undertake sports activity have better postural stability during head rotation and better dynamic visual acuity. The causal effect of these differences is not clear and further investigation is warranted.

Rehabilitation Assessment and Management of Neurosensory Deficits After Traumatic Brain Injury in the Polytrauma Veteran

Neurosensory deficits after traumatic brain injury can frequently lead to disability; therefore, diagnosis and treatment are important. Posttraumatic headaches typically resemble migraines and are managed similarly, but adjuvant physical therapy may be beneficial. Sleep-related issues are treated pharmacologically based on the specific sleep-related complaint. Fatigue is difficult to treat; cognitive behavioral therapy and aquatic therapy can be beneficial. Additionally, methylphenidate and modafinil have been used. Peripheral and central vestibular dysfunction causes dizziness and balance dysfunction, and the mainstay of treatment is vestibular physical therapy. Visual dysfunction incorporates numerous different diagnoses, which are frequently treated with specific rehabilitation programs.

Development of a Pediatric Balance Center: A Multidisciplinary Approach

The growing evidence of the need for pediatric vestibular evaluation, as well as the availability of successful treatment options for children, is attracting the attention of many professionals and sparking much interest in the development of pediatric balance centers in North America. Complete balance function assessment and rehabilitation in children requires specialized knowledge and practices of professionals in multiple disciplines. While individual specialists provide useful test information and recommendations for patients, the collaboration of specialists working in a multidisciplinary fashion allows the information to become more powerful, providing the patients and their families with a comprehensive plan. Currently, there are only a handful of pediatric balance centers in North America and most of the centers have been in existence less than 10 years. Thus, this new initiative is in its infancy. Educating oneself, administrators, referral sources, and interdisciplinary colleagues is crucial for gathering support for the enormous endeavor of developing such a center. There are many resources one can draw from, including the works found in this issue. Our hope is that this special Seminars in Hearing may serve as a companion guide to anyone interested in performing pediatric vestibular evaluations and/or developing a multidisciplinary pediatric balance center.

Bilateral Vestibular Weakness

Bilateral vestibular weakness (BVW) is a rare cause of imbalance. Patients with BVW complain of oscillopsia. In approximately half of the patients with BVW, the cause remains undetermined; in the remainder, the most common etiology by far is gentamicin ototoxicity, followed by much rarer entities such as autoimmune inner ear disease, meningitis, bilateral Ménière’s disease, bilateral vestibular neuritis, and bilateral vestibular schwannomas. While a number of bedside tests may raise the suspicion of BVW, the diagnosis should be confirmed by rotatory chair testing. Treatment of BVW is largely supportive. Medications with the unintended effect of vestibular suppression should be avoided.

Current diagnostic procedures for diagnosing vertigo and dizziness

Vertigo is a multisensory syndrome that otolaryngologists are confronted with every day. With regard to the complex functions of the sense of orientation, vertigo is considered today as a disorder of the sense of direction, a disturbed spatial perception of the body. Beside the frequent classical syndromes for which vertigo is the leading symptom (e.g. positional vertigo, vestibular neuritis, Menière’s disease), vertigo may occur as main or accompanying symptom of a multitude of ENT-related diseases involving the inner ear. It also concerns for example acute and chronic viral or bacterial infections of the ear with serous or bacterial labyrinthitis, disorders due to injury (e.g. barotrauma, fracture of the oto-base, contusion of the labyrinth), chronic-inflammatory bone processes as well as inner ear affections in the perioperative course. In the last years, diagnostics of vertigo have experienced a paradigm shift due to new diagnostic possibilities. In the diagnostics of emergency cases, peripheral and central disorders of vertigo (acute vestibular syndrome) may be differentiated with simple algorithms. The introduction of modern vestibular test procedures (video head impulse test, vestibular evoked myogenic potentials) in the clinical practice led to new diagnostic options that for the first time allow a complex objective assessment of all components of the vestibular organ with relatively low effort. Combined with established methods, a frequency-specific assessment of the function of vestibular reflexes is possible. New classifications allow a clinically better differentiation of vertigo syndromes. Modern radiological procedures such as for example intratympanic gadolinium application for Menière’s disease with visualization of an endolymphatic hydrops also influence current medical standards. Recent methodical developments significantly contributed to the possibilities that nowadays vertigo can be better and more quickly clarified in particular in otolaryngology.

Vestibular rehabilitation following surgical repair for Superior Canal Dehiscence Syndrome: A complicated case report

Superior Canal Dehiscence Syndrome (SCDS) causes auditory and vestibular symptoms. Following surgical repair of the dehiscence, patients often experience dizziness and imbalance. This case report describes a postoperative vestibular exercise program, focusing on the principles of central compensation and habituation, and how it was modified for a patient with delayed progress secondary to strabismus and visual vertigo. A 63-year-old male with history of strabismus eye surgery, right hearing loss, aural fullness, and sensitivity to loud sounds was referred for vestibular rehabilitation (VR). He was seen for one preoperative and six postoperative PT visits over eight months. Outcome measures two weeks postoperative were as follows: Dizziness Handicap Inventory (DHI) 38/100; Timed Up & Go (TUG) 9.92 seconds; Dynamic Gait Index (DGI) 16/24; and a 3-line difference in Dynamic Visual Acuity (DVA). Improved outcomes at discharge included: DHI 18/100; TUG 6.87 seconds; DGI 23/24; and 1-line difference in DVA. He was able to return to work and previously enjoyed recreational activities. Postoperative vestibular rehabilitation programs are functionally and symptomatically beneficial following surgical repair for SCDS. Deviations from expected recovery should be addressed to achieve optimal outcomes as demonstrated in this complicated case report.

Vestibular rehabilitation in benign paroxysmal positional vertigo: Reality or fiction?

The objective of this article is to systematically review the evidence on the effectiveness of vestibular rehabilitation (VR) in patients with benign paroxysmal positional vertigo (BPPV). Relevant published studies about VR in BPPV were searched in PubMed, Google Scholar and Ovid using various keywords. We included trials that were available in the English language and did not apply publication year or publication status restrictions. Studies based on the VR in other peripheral and/or central balance disorders are excluded. Primary outcome was the effect on vertigo attacks and balance. Of 42 identified trials, only 12 trials fulfilled our inclusion criteria and were included in this review. Three of them investigated the role of VR in patients with BPPV comparing with no treatment, two of them evaluated the efficacy of VR versus medications, seven of them have highlighted the benefits of the VR alone or in combination with canalith repositioning procedure (CRP) compared to CRP alone. The studies differed in type of intervention, type of outcome and follow-up time. VR improves balance control, promoting visual stabilization with head movements, improving vestibular–visual interaction during head movement and expanding static and dynamic posture stability. CRP and VR seem to have a synergic effect in patients with BPPV, especially in elderly patients. VR does not reduce the recurrence rate, but it seems to reduce the unpleasantness. So VR can substitute CRP when spine comorbidities contraindicate CRP and can reduce the uptake of anti-vertigo drugs post CRP. Further studies are needed to confirm these encouraging results.

Assessment and rehabilitation of central sensory impairments for balance in mTBI using auditory biofeedback: a randomized clinical trial

Background

Complaints of imbalance are common non-resolving signs in individuals with post-concussive syndrome. Yet, there is no consensus rehabilitation for non-resolving balance complaints following mild traumatic brain injury (mTBI). The heterogeneity of balance deficits and varied rates of recovery suggest varied etiologies and a need for interventions that address the underlying causes of poor balance function. Our central hypothesis is that most chronic balance deficits after mTBI result from impairments in central sensorimotor integration that may be helped by rehabilitation. Two studies are described to 1) characterize balance deficits in people with mTBI who have chronic, non-resolving balance deficits compared to healthy control subjects, and 2) determine the efficacy of an augmented vestibular rehabilitation program using auditory biofeedback to improve central sensorimotor integration, static and dynamic balance, and functional activity in patients with chronic mTBI.

Methods

Two studies are described. Study 1 is a cross-sectional study to take place jointly at Oregon Health and Science University and the VA Portland Health Care System. The study participants will be individuals with non-resolving complaints of balance following mTBI and age- and gender-matched controls who meet all inclusion criteria. The primary outcome will be measures of central sensorimotor integration derived from a novel central sensorimotor integration test. Study 2 is a randomized controlled intervention to take place at Oregon Health & Science University. In this study, participants from Study 1 with mTBI and abnormal central sensorimotor integration will be randomized into two rehabilitation interventions. The interventions will be 6 weeks of vestibular rehabilitation 1) with or 2) without the use of an auditory biofeedback device. The primary outcome measure is the daily activity of the participants measured using an inertial sensor.

Discussion

The results of these two studies will improve our understanding of the nature of balance deficits in people with mTBI by providing quantitative metrics of central sensorimotor integration, balance, and vestibular and ocular motor function. Study 2 will examine the potential for augmented rehabilitation interventions to improve central sensorimotor integration.

Trial registration

This trial is registered at clinicaltrials.gov (NCT02748109)

The Effect of Vestibular Rehabilitation in Patients with Ménière’s Disease: A Systematic Review

Objective

To systematically review the evidence on the effect of vestibular rehabilitation in patients with Ménière’s disease (MD) on balance and dizziness-related quality of life.

Data Sources

A literature search was conducted in the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Web of Science, and CINAHL databases.

Review Methods

Articles were reviewed by 2 independent authors and data were compiled in tables for analysis regarding balance (ie, posturography) and dizziness-specific quality of life in patients with MD. A comprehensive search was performed up to November 2015. Studies on relevance and methodological quality were assessed by means of the Cochrane risk of bias tool. For outcome on balance and quality of life, we calculated mean differences and their 95% confidence intervals.

Results

A total of 986 unique studies were retrieved. Five studies, including a total of 498 patients, fulfilled the eligibility criteria, including 2 randomized controlled trials and 3 prospective cohort studies. There was no study with a low risk of bias. We found inconsistent evidence for the effect of vestibular rehabilitation on balance and dizziness-related quality of life.

Conclusion

Based on the low quality of the selected studies, it is inconclusive whether there is a positive effect of vestibular rehabilitation in patients with MD on balance and dizziness-related quality of life.

Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects

Normal function of the vestibulo-ocular reflex (VOR) coordinates eye movement with head movement, in order to provide clear vision during motion and maintain balance. VOR is generated within the semicircular canals of the inner ear to elicit compensatory eye movements, which maintain stability of images on the fovea during brief, rapid head motion, otherwise known as gaze stability. Normal VOR function is necessary in carrying out activities of daily living (eg, walking and riding in a car) and is of particular importance in higher demand activities (eg, sports-related activities). Disruption or damage in the VOR can result in symptoms such as movement-related dizziness, blurry vision, difficulty maintaining balance with head movements, and even nausea. Dizziness is one of the most common symptoms following traumatic brain injury (TBI) and is considered a risk factor for a prolonged recovery. Assessment of the vestibular system is of particular importance following TBI, in conjunction with oculomotor control, due to the intrinsic neural circuitry that exists between the ocular and vestibular systems. The purpose of this article is to review the physiology of the VOR and the visual-vestibular symptoms associated with TBI and to discuss assessment and treatment guidelines for TBI. Current challenges and future prospects will also be addressed.

A new method to improve the imbalance in chronic unilateral vestibular loss: the organization of refixation saccades

CONCLUSION

VOR adaptation and organization of refixation saccades in a gathered pattern is a process that can be artificially induced in patients with unilateral vestibular loss who have not developed it naturally, improving imbalance and vestibular disability.

OBJECTIVE

To test that temporary grouping of refixation saccades should be linked to better clinical status without gain recovery.

METHODS

A training to induce the refixation saccades into gathered fashion is performed. The outcome measures are handicap level measured by the dizziness handicap index (DHI) and refixation saccades organization pattern measured by a numeric score called 'PR' given by a software developed by the authors. Analysis is done before the training and 1 and 3 months after ending, Non-parametric tests were used for statistical analysis.

RESULTS

This study has included 10 healthy subjects (four males, six females), and 16 patients with chronic unsteadiness due to unilateral vestibular loss (nine vestibular neuritis, four post-surgical vestibular schwannoma, and three cases after intra-tympanic gentamycin in patients with Ménière's disease). The reduction in the DHI score was significant at 1 (p = 0.028) and 3 months (p = 0.042) post-treatment. Also, statistically significant differences were found between the PR score before and PR score 1 (p = 0.005) and 3 months after the treatment (p = 0.003).

An overview of vestibular rehabilitation

Data related to the efficacy of vestibular rehabilitation and its evolution as an intervention are provided. Concepts and various treatment strategies are described, with explanations of why people with uncompensated peripheral and central vestibular disorders might improve with rehabilitation. Various tests and measures are described that are commonly used to examine patients and determine their level of ability to participate in their environment. Factors that affect recovery, both positively and negatively, are described in order to better prognosticate recovery. A case utilizing many of the principles discussed is included to provide insight into how to utilize vestibular rehabilitation with a person with an uncompensated peripheral vestibular loss.

Pilot study of a new rehabilitation tool: improved unilateral short-term adaptation of the human angular vestibulo-ocular reflex

HYPOTHESIS

Unilateral vestibulo-ocular reflex (VOR) short-term adaptation training causes some increase toward the nonadapting side (~30% of increase on adapting side). We conducted a pilot study to determine if the increase could be reduced by providing a visual stimulus during rotations to the nonadapting side.

BACKGROUND

Unilateral vestibular short-term adaptation is a technique that could increase the ipsilesional VOR response of vestibular patients with unilateral hypofunction. However, this technique results in the VOR response increasing for rotations toward the nonadapting (normal) side, which is undesirable because the VOR will be overcompensatory (causing nonstable vision) during head rotations toward the normal side.

METHODS

We built a portable helmet device that sensed horizontal angular head velocity to generate a visual target that required a preset VOR gain (eye velocity/head velocity) for optimal image stabilization that could be set differently for leftward and rightward head rotations. We tested 10 subjects (six controls and four patients with vestibular hypofunction). We measured the active and passive VOR gain during high-peak-acceleration, unilateral, transient head rotations (head impulses) before and after unilateral VOR adaptation training.

RESULTS

In control subjects, for rotations toward the adapting side (target gain = 1.5), the VOR gain increased because of training by 26.1% ± 23.4% during active head impulses and by 14.6% ± 13.0% during passive head impulses. In contrast, for rotations toward the nonadapting side, there were no statistically significant increases.

CONCLUSION

A visual stimulus driving the VOR gain to unity toward the nonadapting side aids unilateral adaptation more so than no visual stimulus.

[Kinesitherapy in patients with the peripheral vestibular system disorders]

INTRODUCTION

Kinesitherapy is widely accepted management in patients with vertigo and imbalance, but there has been inadequate evidence that one form of therapy is superior to another.

THE AIM

of the study was to compare effectiveness of two kinesitherapy protocols in patients with the peripheral vestibular system disorders.

MATERIAL AND METHODS

Fifty patients (mean age 46.0±13.1 year) with vertigo and balance instability lasting over 3 months with unilateral vestibular disorder, confirmed in Videnystagmography, were included in the study. Thirty patients underwent supervised and 20 patients home-based exercise programs. All of them were assessed three times at the baseline, after 4 weeks and 3 months, on vertigo intensity and frequency with the Vertigo Syndrome Scale (VSS), Vertigo Visual Analog Scale (VAS) and clinical unsteadiness with tests (Romberg, Amended Motor Club Assesment (AMCA), Eurofit test - standing on one leg.

RESULTS

In both groups the clinical tasks and the intensity of vertigo in VAS significantly decreased. The mean value of VSS (part physical and emotional)score significantly decreased only in supervised group at the end of 4 weeks and 3 months (p=ns). Recovery was more dynamic in supervised group than home-based exercises group, in AMCA test (3.9 vs. 1.3 s, p<0.05) in Eurofit tests eye open (14.1 vs. 0.9 s, p<0.05) and eye closed (3.5 vs. 1 s, p<0.05).

CONCLUSIONS

In patients with unilateral peripheral vestibular dysfunction supervised and home-based group kinesitherapy is an effective treatment method. In supervised group patients recovery has been faster.

[Application of the new diagnostic tests for vertigo. Differentiated analysis of vestibular function]

Due to the development of new methods such as the vestibular evoked myogenic potential and the video head impulse tests, clinical vestibular diagnostic procedures are currently in an era of change. The spectrum of available techniques renders a specific, quantitative and objective analysis of vestibular reflexes possible for the first time. Moreover, a combination of different methods permits the assessment of different functional areas of the vestibular receptor. In addition to a topological diagnosis, the concept of a differentiated analysis of vestibular receptor function includes evaluation of frequency-specific functional areas (dynamic frequency analysis) and monitoring of temporal changes (time-dependent diagnostics). Consequently, the overall outcome of physiological tests can be viewed from a new perspective. This enables a comprehensive assessment of vestibulopathies in clinical practice and furthers the understanding of these disorders.

[Impact of physiotherapy on quality of life improvement in patients with central vestibular system dysfunction]

THE AIM of the study was to evaluate the impact of physiotherapy on balance stability and quality of life improvement in patients with central vestibular system dysfunction.

MATERIAL AND METHODS

The study was conducted on 31 patients (23 females, 8 males) with vertigo/dizziness and unsteadiness diagnosed for central vestibular system impairment based on videonystagraphy examinations, in ENT Department Medical University of Lodz between 2010-2011 years. Patients' history of diseases were collected. The physiotherapeutic programme was individually introduced during four weeks (five time a week). The intervention included balance training and habituation exercises. At baseline and after patients were evaluated therapy with WHO Quality of Life-BREF (WHOQOL-BREF) and Dizzeness Handicap Inventory (DHI) self-assessment scales. Clinical examination with Romberg and stand one leg tests (eyes opened and closed) was performed.

RESULTS

After therapy statistically significant differences in total DHI score (p<0.005) and 3 subscales: physical, emotional, functional (p<0.05) and WHOQOL-BREF only physical subscale (p<0.05) compared baseline were found. There were no statistical differences between psychological, social relationships and environment subscales. In clinical evaluation significant reduction of unsteadiness in Romberg test (p<0.05) and in stand one leg tests eyes opened and closed tests (p<0.05) were found.

CONCLUSION

In patients with central vestibular system impairment after physical therapy betterment in clinical examination and some subjective self-assessment scales were observed. Lack of significant improvement in psychological, social relationships and environment domain in WHOQOL-BREF subscale indicated that these patients may need more psychological support or extensions in physiotherapy.

Semicircular canal, saccular and utricular function in patients with bilateral vestibulopathy: analysis based on etiology

The diagnosis of bilateral vestibulopathy (BV) is typically established based on bilateral semicircular canal dysfunction. The degree to which both otolith organs-the saccule and utricle-are also impaired in BV is not well-established, particularly with respect to the etiology and severity of BV. The aim of this study was to evaluate semicircular canal, saccular and utricular function in patients with BV due to aminoglycoside ototoxicity and bilateral Menière's disease, and with different severities of BV. Caloric and head impulse testing were used as measures of canal function. Cervical vestibular-evoked myogenic potentials (cVEMP) and ocular VEMPs (oVEMP) were used as measures of saccular and utricular function, respectively. We enrolled 34 patients with BV and 55 controls in a prospective case-control study. Patients with BV were less likely to have saccular (61 %) or utricular (64 %) dysfunction relative to canal dysfunction (100 %). Utricular function differed significantly between patients by etiologic group: the poorest function was found in patients with BV due to aminoglycoside toxicity, and the best function in Menière's disease patients. Canal and saccular function did not vary according to etiology. Further, utricular but not saccular function was significantly correlated with canal function. Saccular and utricular function had the strongest association with Dizziness Handicap Inventory scores relative to canal function. These data suggest that when a patient with BV is identified in a clinical context, oVEMP testing is the most sensitive test in distinguishing between aminoglycoside toxicity and bilateral Menière's disease. Both cVEMP and oVEMP testing may be considered to evaluate the functional impact on the patient.

Progress toward development of a multichannel vestibular prosthesis for treatment of bilateral vestibular deficiency

This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation-inhibition asymmetry, and adapting laboratory MVP prototypes into devices appropriate for use in clinical trials.

Vestibular rehabilitation strategies and factors that affect the outcome

Ever since the introduction of Cawthorne-Cooksey exercises, vestibular rehabilitation (VR) has been gaining popularity in the treatment of the dizzy patient. Numerous studies support the effectiveness of VR in improving balance/walking skills, eye-head coordination and the quality of life of the patient. Different rehabilitation protocols have been used to treat patients with peripheral and central vestibular disorders. Assessment of the patients' progress is based on the patients' selfperception of dizziness and their functional skills. Factors such as age, medication, time of onset of vertigo and home based VR have been evaluated on their effect on the rehabilitation's outcome. The aim of this review is to evaluate rehabilitation strategies and discuss the factors that affect the outcome.

The reliability and response stability of dynamic testing of the vestibulo-ocular reflex in patients with vestibular disease

The purpose of the study was to investigate the test-retest reliability and response stability of the Dynamic Visual Acuity (DVA) and Gaze Stabilization Test (GST) in patients with vestibular disorders. Twenty-nine patients with vestibular disease (16-78 years) participated. Subjects performed the GST and DVA in pitch and yaw planes, twice in one session and once after 7-10 days. The GST output is the maximum head velocity at which the patient was able to identify orientation of the letter E. The DVA output is the change in visual acuity when moving the head compared to static acuity. Subjects indicated their level of dizziness and visual blurring using a visual analog scale. Within- and between-sessions intraclass correlation coefficients ranged between 0-0.5 for the DVA and GST measures, with better correlations for within-session assessments. Response stability (standard error of measurement / mean) of the GST ranged between 21-32% and the DVA ranged between 25-69% with vertical DVA being most influenced by measurement error. Subjects' symptoms did not correlate with performance on either test. The current test protocol needs refinement to enhance reliability and stability in persons with vestibular disorders.