Testing Effectiveness of a Stochastic Noise Stimulator to Immediately Improve Balance and Gait

Gait velocity

Gait will be measured with a set of motion sensors (Xsens MTw Awinda motion sensors). These wearable inertial monitors measure rotational rate, acceleration, magnetic field strength, and temperature. The sensors are about the size of a watch and attach with Velcro bands. The sensors are wirelessly synchronized with each other and the software, eliminating interconnecting cables and minimizing risk of falling. Gait measures will include gait velocity, gait variability, gait synchronization.

Modified Clinical Test of Sensory Interaction on Balance (mCTSIB)

Previous work has demonstrated that posturography provides significant information on vestibular function in the elderly. The mCTSIB will be performed as outlined in the Neurocom geriatric balance assessment to provide an effective initial screening tool. This test involves the subjects standing quietly on a force plate while center of mass and sway are measured with eyes open and closed. To create some instability, subjects will stand quietly on a foam block placed on the force plate with eyes open and then closed. Subjects with poor vestibular function should demonstrate significantly greater sway on tests in which their eyes are closed.

Ocular Torsion

OCR is a reflexive torsional eye movement response to a head tilt that has been attributed to the otoliths. It has been demonstrated that OCR is reduced in patients who lack otolithic inputs. Eye movements during OCR tests will be recorded with a videography system that uses the polar cross-correlation technique to measure ocular counter roll using gray scale information of iris patterns obtained from circular sampling paths at fixed radii from the pupil center. To assess otolithic function, binocular counter roll will be recorded with head upright, and then during passive tilting in a chair to the right and left. During the clinical OCR testing portion, the participant will be roll tilted \~30 degrees (whole body) and the eye is measured in roll for both position and velocity.

Video Head Impulse Testing (vHIT)

Subject will be fitted with lightweight goggles on which a small camera is mounted. The subject is asked to look at a target while the experimenter gives abrupt horizonal head rotations through a small angle to both the left and the right. The head movement speed is measured by the sensor in the goggles, and the image of the eye is captured by the high-speed camera and processed by very fast software to yield eye velocity. This is a standard clinical vestibular test.

Instrumental Timed Up and Go Test (TUG)

Subject will first sit with back against the chair and arms on the armrests. When instructed "Go", the subject will stand up, walk to a marker that is 3 meters away from the chair with their own comfortable and usual speed, and walk back, then sit back down to the chair. Time is taken from the "Go" command until the subject sit back down. This is a standard clinical test for mobility and functional ability with lower times indicate better mobility and lower fall risk.