The sense of balance is so vital to our well-being that it is sometimes called a sixth sense. The human body relies on balance for virtually all kinds of physical activities. Yet, normal people take it for granted and do not fully realize its importance. Without the sense of balance, it is a very difficult task to stand or move on two legs without falling. The major balance organ is a delicate system inside our inner ears called vestibular apparatus, which sends feedback information about the orientation and movement of the head to the brain. The brain uses the vestibular feedback in coordination with vision and proprioception (sensory input from the muscles and joints) to maintain balance of the entire body.
Vestibular disorders due to aging, drug toxicity, viral infections, and surgery, etc. cause degradation or damage of the vestibular sense resulting in loss of vestibular feedback. An individual with vestibular loss experiences various problems including imbalance, dizziness, and vertigo. Vestibular rehabilitation therapy may reduce some of the symptoms through compensation by vision and proprioception. However, the lost vestibular function cannot be fully compensated and balance with vestibular loss is difficult if not impossible, especially in situations such as dim lighting, misleading visual information, or walking on uneven surfaces. Currently no practical devices are available to provide in-situ sensory feedback regarding head movement for patients with vestibular loss in various daily activities such as walking in a park, street, or shopping mall, etc.