Safety and Efficacy of the BrainPort™ Balance Device to Improve Balance in Bilateral Vestibular Hypofunction

Inclusion Criteria: * Documented history of acquired bilateral vestibular dysfunction for a duration of at least one year which has been unsuccessfully treated or reached a plateau with conventional vestibular rehabilitation. * No greater than 2 successful attempts out of 6 on the NeuroCom Equitest Sensory Organization Tests 5 and 6. * Failure on the Rotary Chair Vestibulo-ocular Reflex (VOR) Test as evidenced by a gain of less than or equal to -2 standard deviations at frequencies of .025, and .05 Hz. * Normal corrected vision (20/40 or better). * Able to read and understand the informed consent form, and willing to sign the informed consent form. * Willing to complete all follow-up evaluations required by the study protocol. * Able to stand for a period of 20 minutes in a stationary position with weight evenly distributed without moderate pain, muscle cramping or numbness in the lower extremities. Exclusion Criteria: * Neurological disorders other than bilateral vestibular disorder, as determined by medical history and neurological screening procedure. * Current oral health problems as determined by health questionnaire and an examination of the oral cavity. * Cigarette smokers and those who use chewing tobacco. * Currently taking either benzodiazepine or barbiturate medication. * Any medical condition as determined by the health questionnaire that would interfere with performance on the postural stability evaluation tests. * Known neuropathies of tongue or skin tactile system. * Peripheral neuropathies of the lower extremities. * Prior exposure to BrainPort™ balance device (does not apply to control group subjects who cross over). * 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. * Subjects who have undergone middle ear or other surgery with sacrifice or damage to the chorda tympani, lingual, or hypoglossal nerve. * Subjects who have an implanted device such as a pacemaker or defibrillator. * If the subject is female, she is pregnant. * If the subject is unwilling to discontinue medications for dizziness or imbalance 48 hours prior to beginning the study.