Dizziness
Conditions
Keywords
dizziness, postural balance, rehabilitation
Brief summary
Recent studies suggest that otolith dysfunction is a common finding in individuals with a history of head trauma/blast exposure and/or noise-induced hearing loss. Therefore, otolith dysfunction may be a significant health concern for the Veteran population, and determining optimal intervention strategies for otolith dysfunction is important for VA healthcare. The purpose of this project is to identify optimum stimulus parameters of a novel treatment, off-axis rotation (centrifugation) for otolith dysfunction, in healthy participants.
Detailed description
The primary function of the vestibular (inner ear balance) system is to maintain gaze and postural stability. The vestibular system is comprised of two types of sensory organs (semicircular canals and otolith organs) each with unique contributions to balance. Vestibular Rehabilitation (VR) is the treatment of choice for patients experiencing dizziness, imbalance, and mobility impairments related to vestibular dysfunction. VR typically includes gaze stability exercises, gait and balance training, and general conditioning. Gaze stability exercises were developed based on the concepts of adaptation and substitution with the goal of improving gaze stability by facilitating vestibular compensation of the semicircular canal-mediated vestibulo-ocular reflex (VOR). Many factors that might influence recovery, such as the involvement of different vestibular sensory organs (semicircular canals versus otolith organs) have not been examined to determine their impact on recovery. Most studies examining the effectiveness of VR have used only tests of VOR function (caloric and rotational tests) that measure horizontal semicircular canal to determine vestibular loss. Thus, little is known about interventions to facilitate vestibular compensation of the otolith organs. Recent studies have demonstrated adaptation following otolith organ stimulation using centrifugation (or linear acceleration), but there is no data regarding optimum stimulus parameters. The concept of using centrifugation for otolith adaptation may be similar to using gaze stability exercises for VOR adaptation. Healthy control subjects (n = 5 per experiment) will participate in three separate experiments to determine: (1) the optimum off-axis distance of the rotary chair, (2) the optimum duration of off-axis rotation (OAR), and (3) the optimum OAR stimulation/training schedule.
Interventions
BEHAVIORALCentrifugation Distance
To determine optimal distance off-axis, participants were rotated in a darkened rotary chair booth with 1 ear positioned 3.5 cm off-axis and the other ear positioned on-axis for 1 minute. Participants received 5 sessions in a 1-week period. Following a 2-week washout period, participants were rotated in a darkened rotary chair booth with 1 ear positioned 7.0 cm off-axis and the other ear positioned on-axis for 1 minute. Participants received 5 sessions in a 1-week period.
BEHAVIORALCentrifugation Duration
To determine optimal duration, after a two week washout period, participants were rotated off-axis at 3.5 cm (determined to be optimal in Exp 1) for 3 minutes. Participants received 5 sessions in a 1-week period.
BEHAVIORALCentrifugation Schedule
To determine optimal schedule, after a two week washout period, participants were rotated off-axis at 3.5 cm (determined to be optimal in Exp 1) for 3 minutes (determined to be optimal in Exp 2). Participants received biweekly sessions for a total of 5 sessions.
Sponsors
VA Office of Research and Development
Study design
Allocation
NA
Intervention model
SEQUENTIAL
Primary purpose
OTHER
Masking
NONE
Intervention model description
To determine optimal stimulus parameters for off-axis rotation (OAR), participants progressed through the study starting with off-axis distance (3.5 vs 7.0 cm), off-axis duration (1 vs 3 minutes) and finally training schedule (daily vs biweekly). SVV was measured immediately before and after training. To determine optimal distance, OAR was first performed at 3.5 cm and then 7.0 cm off-axis for 1 minute and the change in SVV compared. Participants trained daily for 5 consecutive days at 3.5 cm followed by a washout period of two weeks, then trained at 7.0 cm. To determine optimal duration, participants were rotated at 3.5 cm off-axis (determined to be optimal) for 3 minutes and the change in SVV was compared to 3.5 cm off-axis for 1 minute. To determine optimal training schedule, participants were rotated at 3.5 cm off-axis for 3 minutes (determined to be optimal) on a biweekly schedule for a total of 5 sessions and change in SVV was compared to the daily training schedule.
Eligibility
Sex/Gender
ALL
Age
18 Years to 69 Years
Healthy volunteers
Yes
Inclusion criteria
* At least 18 years of age * Documented balance or mobility problems, or healthy control without imbalance * Otolith dysfunction or healthy control without vestibular dysfunction
Exclusion criteria
* Progressive neurological disorders and central vestibular abnormalities * Benign paroxysmal positional vertigo * Superior semicircular canal dehiscence * Middle-ear pathology with conductive hearing loss * Lower extremity joint replacement * Cognitive impairment (Mini Mental Status Exam \< 24/30) * Severe depression (geriatric depression scale 10) * Severe anxiety (geriatric anxiety inventory 11/30) * Best-corrected visual acuity worse than 20/40 in the better eye
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Static Subjective Visual Vertical (SVV) | baseline, immediately after 5 sessions of OAR training (1 week) | Static subjective visual vertical (SVV) assesses spatial perception and is influenced by otolith function. Perception of vertical is measured in a darkened room with subject seated upright. The test assesses an individual's ability to adjust a laser line to be parallel with true vertical in the absence of any other visual cues. The start position of line for SVV testing is randomized and participants are instructed to use the track ball to position the line in a vertical position. Five trials are completed, and the software calculates the distance (in degrees) from vertical. The average of the trials is calculated and used for data analysis. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Centrifugation Distance Each subject will complete training at both chair positions (3.5 cm off-axis and 7.0 cm off-axis). Subjects will be randomized to start with either chair position (3.5 cm or 7.0 cm) and have a wash out period of at least 2 weeks in between chair training distance (3.5 cm or 7.0 cm) until static SVV returns to normal.
Participants will be rotated in a darkened rotary chair booth with 1 ear positioned 3.5 cm or 7.0 cm off-axis and the other ear positioned on-axis. Participants will receive 5 consecutive sessions in a 1-week period (Monday-Friday). Static subjective visual vertigo will be assessed at the start and end of each session. | 6 |
| Total | 6 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Centrifugation - Distance | Lost to Follow-up | 1 |
Baseline characteristics
| Characteristic | Centrifugation Distance |
|---|---|
| Age, Continuous | 29.7 years STANDARD_DEVIATION 3.93 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 0 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 6 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 6 Participants |
| Region of Enrollment United States | 6 participants |
| Sex: Female, Male Female | 4 Participants |
| Sex: Female, Male Male | 2 Participants |
| static subjective visual vertical | 1.32 degrees STANDARD_DEVIATION 0.71 |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 6 | 0 / 5 | 0 / 5 | 0 / 5 |
| other Total, other adverse events | 6 / 6 | 4 / 5 | 5 / 5 | 4 / 5 |
| serious Total, serious adverse events | 0 / 6 | 0 / 5 | 0 / 5 | 0 / 5 |
Outcome results
Primary
Change in Static Subjective Visual Vertical (SVV)
Static subjective visual vertical (SVV) assesses spatial perception and is influenced by otolith function. Perception of vertical is measured in a darkened room with subject seated upright. The test assesses an individual's ability to adjust a laser line to be parallel with true vertical in the absence of any other visual cues. The start position of line for SVV testing is randomized and participants are instructed to use the track ball to position the line in a vertical position. Five trials are completed, and the software calculates the distance (in degrees) from vertical. The average of the trials is calculated and used for data analysis.
Time frame: baseline, immediately after 5 sessions of OAR training (1 week)
Population: The progression through the study is sequential with participants first being tested at 3.5 cm and then at 7.0 cm (both for 1 minute duration) after a two-week washout period. Six participants initiated study testing at 3.5 cm for 1- minute duration, but one participant did not continue with the study. Thus, that participants data are available for the dataset at Distance = 3.5 cm and Duration = 1 minute.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Centrifugation Distance - 3.5 cm | Change in Static Subjective Visual Vertical (SVV) | 0.69 degrees | Standard Deviation 0.51 |
| Centrifugation Distance - 7.0 cm | Change in Static Subjective Visual Vertical (SVV) | 0.58 degrees | Standard Deviation 1.47 |
| Centrifugation Duration - 1 Minute | Change in Static Subjective Visual Vertical (SVV) | 0.69 degrees | Standard Deviation 0.51 |
| Centrifugation Duration - 3 Minutes | Change in Static Subjective Visual Vertical (SVV) | 0.89 degrees | Standard Deviation 1.14 |
| Centrifugation Schedule - Daily | Change in Static Subjective Visual Vertical (SVV) | 0.89 degrees | Standard Deviation 1.14 |
| Centrifugation Schedule - Biweekly | Change in Static Subjective Visual Vertical (SVV) | 0.32 degrees | Standard Deviation 1.22 |
Comparison: Null hypothesis: The change in SVV (Post-OAR - Pre-OAR) will not be different for the off-axis distance of 3.5 cm and 7.0 cm.p-value: 0.97t-test, 2 sided
Comparison: Null hypothesis: The change in SVV (Post-OAR - Pre-OAR) will not be different for the centrifugation duration of 1 minute and 3 minutes.p-value: 0.51t-test, 2 sided
Comparison: Null hypothesis: The change in SVV (Post-OAR - Pre-OAR) will not be different for the centrifugation schedule of daily OAR and biweekly OAR for a total of 5 sessions.p-value: 0.44t-test, 2 sided