Head-Mounted Vibrotactile Prosthesis for Patients With Chronic Postural Instability (BALCAP)

The goal of this study is to evaluate a tactile prosthesis that provide individuals who have demonstrated chronic imbalance with help to maintain a correct sense of orientation with respect to the gravity and improve posture control.

The goal of this study is to evaluate a tactile prosthesis that provide individuals who have demonstrated chronic imbalance with help to maintain a correct sense of orientation with respect to the gravity and improve posture control. Chronic imbalance leads to significant problems. This study is designed to evaluate a device which can potentially improve the balance of these patients. The participant will be asked to come to Washington University on three occasions for approximately 2 hours. Between visits, they will be asked to use the device daily (intervention condition) or to not use the device (control condition) for a prescribed period of time doing different activities. They will be provided written instructions from a physical therapist that will be determined by their individual ability. The activities will be typical exercises that are given to people with balance disorders. After 6 weeks of home use, participants will return for the second visit, and will repeat the evaluation. They will then return home and complete the either the control or intervention condition (which was not done the first time) in a crossover design. On their first visit (week 0; baseline) participants will be asked to complete the same kind of tests that evaluated the function of their balance system at the time of their diagnosis. They will have their eye movements recorded using goggles and an infra-red camera while the prosthesis is in place and providing vibration feedback. Computerized Dynamic Posturography (CDP) testing will require them to stand on a platform and perform tests (20 seconds each) with their eyes open or closed, with the platform moving or still, and/or with the visual surround either stable or moving. They will be fitted with a safety harness that will keep them from falling. Next the investigators will evaluate their ability to perform movement tasks while walking (walking down the hall, walking down the hall avoiding objects, changing speeds while walking, going up and down stairs etc). They will walk a 25-foot distance at a comfortable gait speed, and again at a maximum gait speed. Lastly, they will be asked to fill out questionnaires. On their second and last visit, they will repeat the evaluations that were performed during the first visit.

Participants performed exercises daily at home wearing the BALCAP prosthesis for 6 weeks. After 6 weeks, participants performed the control condition (the same exercises without the BALCAP). Tests were performed before and after each 6-week period. Exercises included: (1) standing on a firm surface with feet apart, eyes open and closed; (2) standing on a firm surface with feet together, eyes open and closed; (3) standing on thick footing (e.g., multiple pairs of socks) with feet apart, eyes open and closed; (4) standing on thick footing with feet together, eyes open and closed; (5) standing in a modified Romberg position on a firm surface, eyes open and closed; (6) standing in a Romberg position on a firm surface, eyes open and closed; (7) walking on a firm surface eyes open; (8) walking with thick footing, eyes open; (9) walking with head turns and tilts, eyes open; and (10) walking around a room, with turns and movements other than straight forward walking, eyes open.

Participants performed exercises daily at home for 6 weeks without wearing the BALCAP prosthesis (control), followed by another 6 weeks of the same exercises with the BALCAP prosthesis (intervention). Tests were performed before and after each 6 week period. Exercises included: (1) standing on a firm surface with feet apart, eyes open and closed; (2) standing on a firm surface with feet together, eyes open and closed; (3) standing on thick footing (e.g., multiple pairs of socks) with feet apart, eyes open and closed; (4) standing on thick footing with feet together, eyes open and closed; (5) standing in a modified Romberg position on a firm surface, eyes open and closed; (6) standing in a Romberg position on a firm surface, eyes open and closed; (7) walking on a firm surface eyes open; (8) walking with thick footing, eyes open; (9) walking with head turns and tilts, eyes open; and (10) walking around a room, with turns and movements other than straight forward walking, eyes open.

The noninvasive BALCAP prosthesis offers uses six degrees-of-freedom (6-DOF) sensing to detect postural imbalance and actuate low-amplitude vibrotactile cues directly to the head to provide the wearer with feedback concerning head tilt in the pitch and roll plane.

This outcome compared the Dynamic Gait Index score when the BALCAP prosthesis was worn vs. when it was not worn at baseline in order to evaluate if there is an assistive benefit to wearing the device. The Dynamic Gait Index (DGI) is a clinical tool to assess gait, balance, and fall risk using various walking tasks. The range of scores is 0 to 24. A higher score is better. All participants performed this test at baseline both wearing the BALCAP and not wearing the BALCAP. This test does not measure a change in DGI score over time but compares the results of the test while wearing the BALCAP vs. not wearing the BALCAP during the same evaluation period (baseline).

Change in Computerized Dynamic Posturography (CDP): equilibrium score. Computerized Dynamic Posturography is used to assess balance disorders using a balance platform. CDP is used to determine postural stability; it measures a patient's ability to maintain balance under multiple conditions by testing visual, vestibular, and somatosensory balance components of the body. The equilibrium score is an overall indicator of balance. A score of 100 represents perfect stability and a score of 0 indicates a loss of balance. A higher value is better. This test is intended to ascertain if there is a rehabilitative benefit of using the BALCAP instrument.

The gait speed of each participant was measured over a 25-foot difference when wearing the BALCAP vs when not wearing the BALCAP. This test was performed on all participants at baseline prior to the home studies. A higher value represents faster gait speed. This test is intended to measure the assistive benefit of the BALCAP prosthesis.

Change in Activities-specific Balance Confidence (ABC) Scale. The Activities-specific Balance Confidence Scale is a self-report questionnaire that measures an individual's confidence in performing activities without losing balance. The score range is from 0 to 100. A higher value is better.

Change in Dizziness Handicap Inventory score. The Dizziness Handicap Inventory (DHI) is a common self-report quality of life measure for vestibular disorders. The score range is from 0 to 100 and a lower score is better. This test is intended to ascertain if there is a rehabilitative benefit of using the BALCAP instrument.

Inclusion Criteria: Ambulatory Chronic imbalance for at least 1 year Have reached a functional performance plateau with respect to balance performance Have a DGI score of <19 Fall below age and gender matched normative data for gait speed Exclusion Criteria: Subjects who are unwilling or unable to adhere to all study requirements, including completion of the training period, evaluation tests, and return to clinic for a follow-up visit. Women who are pregnant (women will self-report possible pregnancy).