• To assess the efficacy of the BrainPort balance device in improving balance and gait as measured by the Dynamic Gait Index (DGI) in subjects with documented peripheral vestibular dysfunction [ Time Frame: Baseline and 8 weeks (end of study) ] [ Designated as safety issue: No ]
  

• To assess the safety of electrical stimulation of the tongue during the use of the BrainPort balance device in subjects with documented peripheral vestibular dysfunction. [ Time Frame: Baseline and ongoing for the duration of the study (8 weeks). ] [ Designated as safety issue: Yes ]
  
• To assess improvement in the Activities-specific Balance Confidence scale (ABC). [ Time Frame: Baseline and 8 weeks (end of study) ] [ Designated as safety issue: No ]
  
• To assess improvement in the Dizziness Handicap Inventory (DHI). [ Time Frame: Baseline and 8 weeks (end of study) ] [ Designated as safety issue: No ]
  

Peripheral vestibular dysfunction can be caused by inner ear disorders, drug toxicity, neuritis, or a number of other causes. In the absence of a fully functional vestibular system, the brain often requires retraining to correctly utilize visual and proprioceptive cues to maintain postural stability. People with vestibular dysfunction experience multiple problems with posture control and movement, including an unsteady gait and various balance-related difficulties. These effects make it very difficult to walk in the dark or on uneven surfaces without risk of falling. They are typically referred for conventional vestibular therapy. Many patients improve with therapeutic intervention. Some patients reach a plateau and do not return to their previous level of function. The BrainPort balance device transmits head position information via electrotactile stimulation of the tongue. With training, patients learn to use the positional information to correct their balance.

Participants meeting the study criteria will be randomized to the perceived stimulation or subliminal stimulation group. All participants will be given baseline assessments of postural stability, balance, and subjective well being according to standardized tests. After completing the baseline assessments, each participant will be trained in the clinic using a standard training protocol with the BrainPort balance device. Each participant will participate in 6 clinical training sessions, over a period of 3 consecutive days. Upon completion of the clinic training sessions, participants will continue with a 7½ week period of home use. During this period, the participant will train with the device for 20 minutes 2 times per day and the clinicians will contact the participants weekly. At the end of the home training period (8 weeks from the beginning of the study), all participants will again undergo the tests given at baseline.

Following the data analysis, subjects that have completed the 8 week study and were originally assigned to the group with inferior results will be given the opportunity to use the device that showed superior results in the data analysis.