Concurrent Vestibular Activation and Postural Training Using Virtual Reality (VR-HS-WST)

Effects of Concurrent Vestibular Activation and Postural Training on Postural Control Using Virtual Reality

Postural instability is a common symptom of vestibular dysfunction that impacts a person's day-to-day activities. Vestibular rehabilitation is effective in decreasing dizziness, visual symptoms and improving postural control through several mechanisms including sensory reweighting. As part of the sensory reweighting mechanisms, vestibular activation training with headshake activities influence vestibular reflexes. However, combining challenging vestibular and postural tasks to facilitate more effective rehabilitation outcomes is under-utilized. The novel concurrent headshake and weight shift training (Concurrent HS-WST) is purported to train the vestibular system to directly impact the postural control system simultaneously and engage sensory reweighting to improve balance. Healthy older adults will perform the training by donning a virtual reality headset and standing on the floor or foam pad with an overhead harness on and a spotter present to prevent any falls. The investigators propose that this training strategy would show improved outcomes over traditional training methods by improving vestibular-ocular reflex (VOR) gains, eye movement variability, sensory reweighting and promoting postural balance. The findings of this study may guide clinicians to develop rehabilitation methods for vestibular postural control in neurological populations with vestibular and/or sensorimotor control impairment.

A cross-over design will be used with group one receiving the training intervention for 7 days, a 6-day washout period, and a 7-day no-training period. Group two will follow the reverse sequence.

A cross-over design will be used with group one receiving the training intervention for 7 days, a 6-day washout period, and a 7-day no-training period.

Horizontal and vertical vestibulo-ocular reflex (VOR) gain will be assessed using the video head impulse test (vHIT; ICS, Otometrics, Taastrup, Denmark). Twenty head impulses each will be performed to assess each direction of the semicircular canals with participant in a seated position.

Horizontal and vertical eye movements will be assessed during force plate perturbation trials using BlueGain electro-oculography (EOG) device (Cambridge Research Systems). Participants will stand on a force plate perturbation device with EOG electrodes affixed on eye muscles to record eye movements during toes up (simulating being pushed backward) and toes down (simulating being pushed forward) perturbation rotation trials.

Electromyography (EMG) will be assessed during force plate perturbation trials using Delsys Trigno wireless sensors (Delsys Inc., Boston, MA). Participants will stand on a force plate perturbation device with EMG sensors placed on postural muscles to record electrical activity during toes up (simulating being pushed backward) and toes down (simulating being pushed forward) perturbation rotation trials.

Electromyography (EMG) will be assessed during force plate perturbation trials using Delsys Trigno wireless sensors (Delsys Inc., Boston, MA). Participants will stand on a force plate perturbation device with EMG sensors placed on postural muscles to record electrical activity during toes up (simulating being pushed backward) and toes down (simulating being pushed forward) perturbation rotation trials.

Equilibrium and composite scores will be assessed by the Modified Clinical Test for Sensory Interaction on Balance (MCTSIB; NeuroCom®, Natus Medical Inc., Pleasanton, CA) during quiet stance. The MCTSIB requires the participant to stand upright as stable as possible for 10 s under four different conditions: (1) eyes open (EO) on a stable surface (SS), (2) eyes closed (EC) on SS, (3) EO on foam surface (FS), (4) EC on FS.

Sensory ratios will be assessed by the Modified Clinical Test for Sensory Interaction on Balance (MCTSIB; NeuroCom®, Natus Medical Inc., Pleasanton, CA) during quiet stance. The MCTSIB requires the participant to stand upright as stable as possible for 10 s under four different conditions: (1) eyes open (EO) on a stable surface (SS), (2) eyes closed (EC) on SS, (3) EO on foam surface (FS), (4) EC on FS.

Inclusion Criteria: Able to stand independently (without an assistive device) This study requires participants to perform postural assessments including reactive balance following mechanical perturbations. Participants will also perform headshake activities and weight shift training in standing for 20 mins will mini breaks. Participants must be between the ages of 55-80. Exclusion Criteria: Participants with evidence of: Concussion, vestibular, balance or oculomotor issues for the prior 6 months. Neuropathic conditions, particularly affecting the lower extremities. Participants with this issue will have sensory impairments which can affect their sensory assessment. Current musculoskeletal deficits including significant postural abnormalities (signs of spinal, pelvic and leg length discrepancies). Pain or limitations in neck range of motion. Recent (within 6 months) orthopedic surgery that impacts postural training. Visual Impairment ○ Participants must be able to see and follow targets in the virtual reality environment. Therefore, subjects must have 20/50 (corrected) vision. Subjects who are blind cannot participate.