Abstract
Objective
To compare computerized vestibular retraining therapy (CVRT) to a home exercise program (HEP) for the treatment of unilateral vestibular deficits.
Study Design
Randomized, unblinded, interventional study with single crossover.
Setting
This study was performed in a tertiary neurotology clinic.
Methods
Individuals with a stable unilateral vestibular deficit present for greater than 6 months, confirmed with videonystagmography and vestibular evoked myogenic potential testing and scoring >30 on the dizziness handicap inventory, received either 12 twice‐weekly sessions of CVRT or 6 weeks of HEP. Outcome measures were the limits of stability test with submeasures: reaction time; directional control; movement velocity; endpoint and maximum excursion; endpoint and maximum functional stability region.
Results
CVRT (n = 18), but not HEP (n = 12), was associated with improvement in all measures and with fewer instances of loss of balance during testing. CVRT was superior to HEP for directional control (24.0; 95% CI 4.4‐43.6; P = .01), movement velocity (1.5; 95% CI 0.6‐2.3; P < .001), and endpoint excursion (21.1; 95% CI 4.8‐37.4; P < .01). Improvements in directional control (23.0; 95% CI 1.1‐45.0; P = .046) and movement velocity (1.3; 95% CI 0.4‐2.2; P = .04) were greater for HEP/CVRT crossover than for HEP alone. There were no adverse effects of either treatment.
Conclusion
CVRT improved postural stability in the limits of stability test. CVRT was associated with greater improvement than HEP in lean angle, accuracy, and speed of volitional leaning.
Trial Registration
Clinicaltrials.gov NCT05115032 (https://clinicaltrials.gov/study/NCT05115032).
Keywords: dizziness, postural balance, rehabilitation, vestibular system
An estimated 35% of adults in the United States experience some form of vestibular dysfunction and prevalence increases with age. 1 In a recent meta‐analysis, the majority of individuals who had experienced a fall were found to have a vestibular deficit, and vestibular dysfunction was associated with reduced walking function. 2 In the United States, falls are estimated to account for 0.85% to 1.5% of all healthcare costs, 3 and the risk of wrist and hip fractures is greater in those with vestibular dysfunction. 4 Furthermore, individuals who experience a fall are likely to limit their activities and fear future falls, 5 leading to isolation and mental health problems. 6 , 7
The World Fall Prevention Guidelines recommend fall risk assessment (FRA) and referral and intervention for those at intermediate to high risk of falling. 8 The limits of stability (LOS) test measures an individual's ability to volitionally lean in the anteroposterior and mediolateral axes and may be a useful tool for FRA. Studies have suggested that the LOS test is useful for FRA—poor performance on the LOS was associated with a history of frequent falls in older adults, 9 , 10 and aspects of the LOS, such as velocity 11 , 12 and measures of sway area, 13 have been associated with increased risk of falling. The LOS test can be used to measure the area within which individuals can safely lean without falling, termed the functional stability region (FSR). 14 An individual with a small FSR feels as though they are always just a small displacement away from falling, whereas one with a large FSR is comfortably able to make postural adjustments to maintain their balance within their theoretical LOS.
Vestibular rehabilitation is widely recommended for individuals at risk of falling due to vestibular deficit, 15 Parkinson's disease, 16 and associated with aging, 8 among other factors. However, it is not clear which balance intervention protocol is the most effective, whether different underlying causes of instability benefit from different interventions, or how supervised exercises compare to self‐guided or technologically guided exercises. 15 Many individuals with persistent disability due to unilateral vestibular deficit do not achieve adequate resolution of their symptoms despite undergoing treatment widely supported by evidence. 17 , 18
Computerized vestibular retraining therapy (CVRT) uses a moving platform and a wrap‐around visual display to systematically challenge patients to integrate concordant and conflicting sensory information and seeks to improve their postural stability and reduce their risk of falls. In a pilot study, CVRT was found to improve both subjective measures of vestibular disability and objective posturography measures, including the LOS and FSR, in 13 patients with persistent symptoms of imbalance attributed to objectively determined unilateral vestibular deficits. 19 , 20 , 21 That pilot study informed the present study, in which patients with moderate to severe disability due to persistent unilateral vestibular deficits, lasting at least 6 months, were randomly assigned to either a home exercise program (HEP) or CVRT. This study included a one‐way crossover design whereby the HEP group was offered CVRT after completion of their full course of HEP. We hypothesized that CVRT would result in greater improvements in LOS scores and in the FSR area than HEP. The secondary hypothesis was that patients in the HEP group who had already completed the control treatment would demonstrate greater improvements in LOS scores and FSR after completing the HEP and CVRT in sequence than after HEP alone.
Methods
This unblinded, interventional, randomized controlled trial was approved by the Clinical Research Ethics Board at the University of British Columbia (H21‐03343), and all experiments were performed in accordance with relevant guidelines, regulations, and the Declaration of Helsinki. The study has been registered (Clinicaltrials.gov registration NCT05115032; October 29, 2021). All participants provided written informed consent.
Participants were recruited between January 17, 2022, and October 22, 2022, from a tertiary otology clinic in British Columbia, Canada. Data collection for the primary outcome was completed on December 15, 2022. Eligible patients were aged between 18 and 80 and reported symptoms of imbalance present for more than 6 months, which negatively affected their day‐to‐day activities. To be included in the study, the symptoms were clinically assessed to be caused by a stable vestibular deficit rather than an active or irritative vestibulopathy based on the criteria of the Barany Society International Classification of Vestibular Disorders (ICVD‐1) consensus classification of vestibular symptoms. 22 Objective determination of unilateral peripheral vestibular deficit required at least one of the following: (a) unilateral weakness during videonystagmography (VNG), as defined by a 25% or greater difference between ears using bithermal caloric testing; (b) significant cervical or ocular vestibular evoked myogenic potential (VEMP) interaural asymmetry, or absent cervical or ocular VEMP responses in one ear with intact responses in the other ear. 23 Participants were excluded if they scored ≤30 on the dizziness handicap inventory (DHI), indicating mild disability. We excluded individuals who exhibited fluctuating symptoms of an active vestibulopathic cause within the last 6 months, such as active Ménière's disease (characterized by fluctuating hearing loss, tinnitus and vertiginous exacerbations lasting >20 minutes according to American Academy of Otolaryngology–Head and Neck Surgery criteria) 24 ; patients with concurrent diagnosis of benign paroxysmal positional vertigo (BPPV); or patients with clinical and audiometric evidence of a perilymphatic fistula, or otosyphilis. We also excluded those with a deficit that precluded providing informed consent or completing the rehabilitation exercises, such as orthopedic, or neurological deficits.
The estimated required sample size was calculated using an α value of .05 and a β value of .2 (for a power of 80%) using the DHI results from the pilot study comparing mean DHI before treatment (57 ± 15) and after treatment (35 ± 20). This assumes no benefit for treatment in arm 2. The calculated sample size is 26, and we sought a target enrollment of 30 participants. The target enrollment was increased due to higher‐than‐expected withdrawals in the HEP group. Enrollment was closed at 37 as the pool of eligible participants was exhausted.
Randomization
Participants were randomly assigned to receive either CVRT or HEP by a computer‐generated 1:1 blocked randomization sequence with randomly selected block sizes (either 2, 4, or 6 per block). Allocation concealment was achieved through sequentially numbered, sealed, opaque envelopes, which were assigned to a participant in advance of opening. The study member who generated the allocation sequence and prepared the envelopes did not enroll or assign participants.
Interventions and Assessments
Consenting participants were invited to the clinic for their baseline assessment. The participants completed the LOS test, from which the outcomes reported in this study were derived. The LOS test measures the participants' performance in translating their center of pressure (COP) towards a target indicated on the display and includes several submeasures: (a) reaction time measures the delay between when the target is indicated on the screen and when the subject begins moving, (b) directional control measures how much of the participant's movement was in the target direction, (c) movement velocity measures, in degrees per second (deg/s), the rate at which the subject translates their COP towards the target, (d) endpoint excursion measures, as a percentage of their theoretical maximum, how far towards the target they were able to lean in their first continuous motion, and (e) maximum excursion measures the furthest translation towards the target they achieved during the trial. We also recorded how many times the subject experience loss of balance (LOB) and either took a step or required rescue by the safety harness. Participants also completed the sensory organization test (SOT) as well as three participant‐reported measures: the DHI, the activities‐specific balance confidence (ABC) scale, and the falls efficacy scale‐international (FES‐I), the results of which have been published. 25
Participants in the CVRT group completed 12 twice‐weekly sessions of CVRT in the clinic. The CVRT training was performed on a Bertec Balance Advantage computerized dynamic posturography (CDP) system (Bertec). 26 The system is equipped with a library of preprogrammed exercises. The principal investigator (E.A.D.) assembled a sequence of exercises (approximately eight exercises per session for about 20‐30 minutes total session time). During these exercises, participants were challenged to volitionally shift their weight along the lateral and anteroposterior axes as directed by an interactive display or to maintain their balance, while the visual display and support surface either gave congruent sensory feedback or incongruent feedback (ie, created the illusion of rotation). The exercises grew progressively more difficult over the course of the treatment protocol by changing several parameters: (1) the gain between the measurement of the COP by the platform and the movement of the cursor on the display, (2) the degree to which the platform tilts forwards and backwards, (3) the time allowed for participants to complete an exercise or the speed at which they had to respond to visual stimuli, and (4) the complexity of the visual environment (Supplemental Table S1, available online). The protocol included repetition to consolidate learning. The exercise programs were predetermined, and each participant received the same protocol, except to account for the laterality of their deficit.
Participants in the HEP group were given an exercise booklet, 27 which the principal investigator reviewed with them and demonstrated the exercises. Participants were asked to perform the exercises at home twice daily for the intervention period of 6 weeks. The exercises involved nodding and shaking of the head with eyes open looking in the direction the head is pointing, or fixed on a point in front of them, or with eyes closed. The starting difficulty for the exercises was determined using the timed exercise scoring test, which is detailed in the booklet. Participants were instructed to perform this test weekly to gauge when to progress to a more difficult variation of the exercise. During the 6‐week treatment period, a study member contacted participants by phone every week to encourage adherence and answer questions.
After completion of the assigned intervention, participants returned to the clinic to repeat the assessments. Upon completion of this phase, participants assigned to the HEP group were offered the opportunity to receive the CVRT intervention. This began immediately after the postintervention assessment. Upon completion of the 12 sessions of the CVRT protocol, these participants repeated the assessments once again.
Analysis
Demographic variables are reported as a percentage of the total or as median and range. Questionnaires were scored according to instructions. The areas of FSRs were calculated from LOS excursion scores. Endpoint FSR is the sum of areas between adjacent endpoint excursion limits, and maximum FSR is the sum of areas between adjacent maximum excursion limits. 14 Changes in scores are reported as mean change and 95% confidence interval (95% CI). Between‐group comparisons of categorical variables were analyzed using the χ 2 test, and continuous demographic variables were analyzed using the Mann‐Whitney test.
Within group comparisons were performed using Kruskal‐Wallis testing with Dunn's multiple comparison test. Comparisons of response between treatments (CVRT, HEP, and HEP & CVRT crossover) were performed by one‐way analysis of variance (ANOVA) with Bonferroni's multiple comparisons test. Analysis was performed using Prism 9 version 10.4.2 (GraphPad Software). This study followed the STROBE guidelines for reporting cohort studies.
Results
This study enrolled 37 participants and randomly assigned them to either the CVRT group (n = 20) or the HEP group (n = 17). Two withdrew from the CVRT group before completing the intervention, and five withdrew from the HEP group. Of the 12 participants who completed the HEP intervention, 11 went on to complete the crossover to CVRT (Figure 1). The groups were similar with respect to age, vestibular diagnosis, and symptom at baseline (Table 1). No participants were using vestibular suppressants at the time of enrollment or during the study. There were no adverse effects of either treatment. All participants had undergone previous physiotherapy for their balance disorder.
Figure 1.
Trial profile. CVRT, computerized vestibular retraining therapy; DHI, dizziness handicap inventory; HEP. home exercise program.
Table 1.
Participant Demographics, Vestibular Test Results, and Assessment Measures Before Treatment a
| Home exercise program (n = 12) | Computerized vestibular retraining therapy (n = 18) | P value | |
|---|---|---|---|
| Median age (range) | 61.5 (27‐76) | 56 (25‐72) | .09* |
| Sex | 9 female/3 male | 9 female/9 male | .26† |
| Etiology of deficit | |||
| Head injury | 3 (25%) | 3 (17%) | .77 † |
| Ménière's disease | 3 (25%) | 7 (39%) | .58 † |
| Vestibular neuronitis | 6 (50%) | 8 (44%) | .43 † |
| Abnormal vestibular test | |||
| VNG | 6 (50%) | 11 (61%) | .71† |
| oVEMP | 9 (75%) | 10 (56%) | .44† |
| cVEMP | 9 (75%) | 10 (56%) | .44† |
|
Pretreatment assessment Median score (range) |
|||
| DHI | 53 (32‐88) | 51 (30‐82) | .67* |
| ABC | 55.6 (21.9‐88.8) | 60.9 (21.9‐91.9) | .57* |
| FES‐I | 34 (17‐57) | 32 (19‐48) | .67* |
| SOT composite | 61.5 (35‐74) | 64.5 (36‐81) | >.999* |
Abbreviations: ABC, activities‐specific balance confidence; cVEMP, cervical vestibular evoked myogenic potential; DHI, dizziness handicap inventory; FES‐I, falls efficacy scale‐international; oVEMP, ocular vestibular evoked myogenic potential; SOT composite, sensory organization test composite score of conditions 1 to 6; VNG, videonystagmography.
Assessment scores reported as medians and range. P values were calculated by either a two‐tailed Mann‐Whitney test (*) or a chi‐square test (†).
During the baseline assessment, 5 of 18 participants in the CVRT group experienced LOB and required rescue by the harness, and 1 had multiple instances of LOB (seven LOB total). Following CVRT, there was a decrease to one LOB (P = .03). In the HEP group, two participants experienced an LOB (three LOB total) before treatment, and three participants experienced LOB (four LOB total) after treatment (Figure 2, top left).
Figure 2.
Incidence of loss of balance and mean loss of balance measures before and after either computerized vestibular retraining therapy (CVRT) or home exercise program (HEP). Error bars indicate 95% confidence interval, and P values are given above for pairwise comparisons. P values > .9 are not shown.
Following CVRT, reaction time, directional control, movement velocity, endpoint, and maximum excursion all improved, whereas there were no changes among these measures in the HEP group (Figure 2, Table 2). Endpoint FSR increased in the CVRT group but not in the HEP group (Figure 3, Table 2).
Table 2.
Change in Limits of Stability Measures Pretreatment and Posttreatment a
| CVRT group (n = 18) | HEP group (n = 12) | HEP group following crossover to CVRT (n = 11) | P value | |
|---|---|---|---|---|
| Reaction time, s | −0.4 (−0.7 to 0.2) | −0.1 (−0.4 to 0.3) | −0.3 (−0.7 to 0.1) | .14 |
| Directional control, % | 23.1 (12.2‐34.0) | −1.0 (−14.4 to 12.4) | 19.5 (2.5‐36.4) | .009 |
| Movement velocity, deg/s | 1.6 (1.1‐2.1) | 0.1 (−0.5 to 0.8) | 1.4 (0.7‐2.1) | <.001 |
| Endpoint excursion, % | 22.9 (12.8‐33.0) | 1.8 (−10.6 to 14.3) | 20.0 (5.9‐34.1) | .008 |
| Maximum excursion, % | 17.6 (5.5‐29.6) | 2.6 (−12.1 to 17.3) | 16.2 (0.1‐32.3) | .17 |
| Endpoint FSR | 8564 (5778‐11,349) | 1820 (−2292 to 5931) | 5844 (1081‐10,606) | .02 |
| Maximum FSR | 7550 (3583‐11,518) | 3367 (−1466 to 8199) | 6424 (688‐12,161) | .36 |
Abbreviations: CVRT, computerized vestibular retraining therapy; FSR, functional stability region; HEP, home exercise program.
Changes given as means and 95% confidence intervals. P values are from between‐group analysis by one‐way analysis of variance.
Figure 3.
Endpoint functional stability region (FSR) before treatment and after treatment. The polygons show FSR area as a percent of theoretical maximum for the computerized vestibular retraining therapy (CVRT) group (left) and home exercise program (HEP) group and crossover (right).
Crossover
After completion of 6 weeks of HEP, 11 of 12 participants in this group completed a full course of CVRT. The incidence of LOB during the LOS test among the 12 participants was 3 before treatment and was 4 after HEP alone. Following HEP and CVRT, there were two instances of LOB among 11 participants, which was not different from either baseline (P = .73) or after HEP alone (P = .48). Although HEP alone conferred no changes in LOS test measures, adding CVRT was associated with significant improvement over baseline in directional control, movement velocity, endpoint excursion, and maximum excursion (Figure 4, Table 2). There was no change in endpoint or maximum FSR after HEP; however, the combination of HEP and CVRT increased both endpoint and maximum FSR compared to baseline (Figure 3, Table 2).
Figure 4.
Incidence of loss of balance and mean limits of stability measures before treatment and after either home exercise program (HEP) alone or HEP and computerized vestibular retraining therapy (CVRT) in sequence. 95% confidence interval and P values are indicated. P values > .9 are not shown.
Comparison Between Treatments
Compared to the HEP group, the CVRT group demonstrated greater improvement in directional control (mean difference 24; 95% CI 4.4‐43.6; P = .01), movement velocity (1.5 deg/sec; 95% CI 0.6‐2.3; P < .001), and endpoint excursion (21.1; 95% CI 4.8‐37.4; P < .01); however, we observed no difference between the CVRT and HEP groups for the rate of LOB, reaction time, or maximum excursion (Figure 5). The change in endpoint FSR after treatment was significantly greater for CVRT than for HEP (6744, 95% CI 1060‐12,428, P = .02), whereas there was no difference between treatments for maximum FSR (4184, 95% CI −2930 to 11,297, P = .33).
Figure 5.
Mean changes, with 95% confidence intervals, in rate of loss of balance and in limits of stability measures following treatment. P values are given for pairwise comparisons. P values > .9 are not shown. CVRT, computerized vestibular retraining therapy; HEP, home exercise program.
Considering the HEP allocated/crossover participants only, the combination of HEP followed by CVRT was associated with greater improvement in directional control (mean difference 23.1; 95% CI 1.1‐45.0; P = .046) and movement velocity (1.3; 95% CI 0.4‐2.2; P = .04) compared to after HEP alone; however, there was no additional improvement of adding CVRT after HEP in the rate of LOB, reaction time, endpoint excursion, or maximum excursion (Figure 5). There were no differences in change in any of the LOS measures between the participants who received HEP and CVRT in sequence compared to the participants who received CVRT alone (Figure 5).
Discussion
This study compares a novel balance intervention, CVRT, against HEP, a program of prescribed exercises performed at home, that is similar to commonly recommended, evidence‐based, exercises and reports changes in the LOS test associated with these interventions. The rationale for the LOS test is similar to that of the functional reach test (FRT) but has the benefits of being quantitative and of assessing volitional lean angle in all directions. The literature supports an association between performance on the LOS test and fall risk in older people 9 , 10 , 11 , 12 , 28 and in individuals with Parkinson's disease 29 ; however, there is no consensus for how to best measure fall risk in people with vestibular deficits.
CVRT was associated with improvement in all measures of the LOS. Lean angle, as measured by the endpoint and maximum excursion, increased, consistent with greater confidence as participants leaned close to their theoretical limit. Directional control showed greater accuracy, and the incidence of LOB during the test decreased. Endpoint excursion and FSR, which measure displacement in the participant's first continuous movement, increased following CVRT. The improvement in maximum excursion and maximum FSR was less impressive, suggesting that, before treatment, participants could lean towards their theoretical limit but did so slowly, with poor accuracy, and their progress was interrupted by pauses or changes in direction. The improvement in the endpoint measures shows that they leaned to a greater angle, more quickly, with greater accuracy, and with a lower LOB rate. It would be expected that these changes, applied to activities of daily living, would result in greater confidence, increased capability, and reduced risk of falling. Accordingly, these participants reported improvements in scores for the DHI, the ABC scale, and the FES‐I. 25 In the HEP group, there were no changes in any of the LOS measures, and participants who completed CVRT after HEP had similar LOS scores to those who completed CVRT alone.
Incidence of LOB decreased following CVRT, consistent with our single‐group pilot study 20 ; however, the between‐group difference in LOB rate was not significant. That said, the finding that CVRT improves postural control and reduces LOB suggests that CVRT would be expected to improve stability and reduce fall risk. Measuring fall incidence following CVRT would be a valuable avenue for future research. We found that HEP did not confer measurable benefits to postural stability, despite evidence that treatments similar to HEP promote improve visual acuity 30 , 31 and patient‐reported symptoms. 32 , 33 CVRT, thus, seems to be an effective intervention as part of a multimodal treatment approach.
Traditional vestibular rehabilitation exercises may seek to alleviate symptoms and discomfort through habituation to asymmetric or absent vestibular signals and adaptation to visual blurring due to retinal slip. These exercises, further, may seek to promote substitution of vision or somatosensation to compensate for vestibular hypofunction. 34 However, many exercise protocols involve repetitive movements with congruent stimuli—that is, where vision, somatosensation, and vestibular signals are all in agreement. In such circumstances, substitution of vision or somatosensation is an effective strategy. CVRT employs similar repetitive exercises but includes tasks in which vision and somatosensation may be in conflict with true vertical. Thus, individuals are trained to integrate signals from vision, somatosensation, and from their remaining functional vestibular senses to maintain balance in a dynamic environment. 35 We posit that the sensory conflict presented in these exercises better equips individuals to deal with complex, dynamic tasks of daily life and, thus, leads to greater self‐reported confidence and reduced perceived disability. 25
CDP‐assisted interventions for unilateral vestibular deficits have been studied before, 36 , 37 and the reported outcomes have been positive; however, the subjects in these studies had general instability with a history of falls but no objectively determined diagnosis of vestibular deficit, and the protocols used were not clearly described. This study provides evidence for CDP‐assisted therapies in a well‐defined cohort of patients and with a detailed, replicable protocol. 25
This study enrolled participants with unilateral vestibular deficits diagnosed by objective criteria, namely, VNG and VEMP testing. Equipment for vestibular ocular reflex assessment by rotary chair examination was not available in our clinic. We omitted video head impulse testing (vHIT) from our battery because, at the time of planning and enrollment, a broad consensus regarding vHIT gain and refixation saccade criteria was lacking. A recent study found a high rate of false positive results when using the gain parameter alone and identified the importance of refixation saccade parameters including frequency, velocity, and scatter as being critical to the evaluation of visual gain calculation. 38 These criteria will inform our research going forward.
Although the underlying causes of deficits among participants varied (Table 1), the focus of this study on stable, objectively determined, unilateral deficits strengthens the interpretation of our findings for this cohort. However, it is uncertain whether these findings may be generalizable to other patient groups. We have recently published an analysis, from a single‐group pilot study of CVRT, of sensory ratios of the SOT. These findings offer clues into the compensation mechanisms underpinning the changes in global balance observed after CVRT. Future research of CVRT in patients with other vestibular pathologies would be valuable to determine which patients may benefit from CVRT and whether the sensory integration changes associated with CVRT vary when the deficits arise from divergent underlying causes or treatment is initiated during the acute phase of vestibular loss.
The World Guidelines for Fall Prevention recommends intervention for those at intermediate or high risk based on history of falls and responses to the “Three Key Questions” (1. Have you fallen in the past year, 2. Do you feel unsteady when standing or walking? 3. Do you have worries about falling?). 8 However, the results of the meta‐analysis by Donovan et al suggest that those latter two questions offer little insight into an individual's vestibular function, which increases the risk of falls regardless of age or sex. 2 In a meta‐analysis, fallers with vestibular dysfunction did not report poorer balance confidence or more severe dizziness than those without a diagnosis of vestibular dysfunction, and the majority of fallers with a vestibular deficit reported no dizziness or vertigo symptoms. 2 These findings underscore the importance of screening for vestibular function as part of FRA strategies.
In this study, we found that CVRT was associated with improvements in reaction time, directional control, movement velocity, and endpoint excursion that were greater than for HEP for individuals with unilateral vestibular deficits. Considered alongside our previous report showing CVRT‐associated improvements in participant‐reported disability and objective posturographic measures, 25 these findings support a role for CVRT, as part of a multimodal treatment approach, to provide complementary therapeutic outcomes to current therapies. Research comparing CVRT against, and in combination with, such therapies as supervised vestibular physiotherapy would be a valuable area for future research.
Limitations
There was a higher withdrawal rate in the HEP group, which is a potential source of bias and resulted in fewer than expected participants in this group (n = 12). In total, 11 completed the crossover to CVRT. One participant who was allocated to HEP was entered into the CVRT group due to human error, and they were included as if they had been allocated to CVRT. Participants in the CVRT group completed a known schedule and total “dose”; however, adherence to the protocol by participants in the HEP group may have been variable despite weekly telephone interviews and counseling. The one‐sided crossover design did not allow for comparison between groups who received an equal treatment dose nor account for a potential effect of treatment order. The researcher who oversaw the treatment and those who performed the analysis were not blinded.
Author Contributions
Eytan A. David, conception of experimental treatment, design of the study protocol, screening and enrollment of participants, acquisition and analysis of data, interpretation of results, and co‐writing of the manuscript; Navid Shahnaz, design of the study protocol, interpretation of results, critical review and cowriting of the manuscript; Isabel Wiseman, data acquisition and review of the manuscript; Yael David, data acquisition and review of the manuscript; Chris L. Cochrane, design of the study protocol, data analysis, interpretation of results, and cowriting of the manuscript.
Disclosures
Competing interests
The authors declare that there is no conflict of interest.
Funding source
This study received no funding.
Supporting information
Computerized vestibular retraining therapy (CVRT) protocol. Detailed protocol and instrument settings for CVRT using the Bertec Balance Advantage system.
Data Availability Statement
Following publication, the data that underlie the results reported in this article are available from the corresponding author to researchers who provide a methodologically sound proposal and sign a data access agreement, the conditions of which must protect participant confidentiality.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Computerized vestibular retraining therapy (CVRT) protocol. Detailed protocol and instrument settings for CVRT using the Bertec Balance Advantage system.
Data Availability Statement
Following publication, the data that underlie the results reported in this article are available from the corresponding author to researchers who provide a methodologically sound proposal and sign a data access agreement, the conditions of which must protect participant confidentiality.