Effects of a Virtual Reality-based Dual-task Exercise on Vestibular Function in Patients With Chronic Peripheral Unilateral Vestibular Hypofunction

In a close interplay of sensory and motor functions, the brain constantly evaluates intrinsic and extrinsic movements, creating an inner - always subjective - representation of the stability. If there is an acute or chronic imbalance ("mismatch"), a multisensory misperception can occur. This is perceived subjectively as dizziness. Dizziness is the third most common neurological cause of an emergency with 11-13% after headache and stroke.

The central vestibular system is often involved in dizziness. The organ is part of the inner ear and is located in the petrous bone. It consist of macula organs, which are responsible for the detection of linear accelerations, and semicircular canals, which perceive the head velocity. Furthermore, the central vestibular system provides ocular muscles and the spinal cord with output, in order to control three reflexes. The vestibulo-ocular reflex (VOR) is responsible for a clear vision while the head is rotating, whereas the vestibulo-collic reflex (VCR) innervates the neck musculature in order to fix the head. The purpose of the vestibulo-spinal reflex (VSR) is the stabilization of the body by compensatory movements. In terms of restoring vestibular functioning, compensation can be classified into adaptation, substitution and habituation. Adaptation enhances the VOR, which is equivalent to restoration. Substitution is distinguished in literature between sensory and behavioral, in which the sensorial substitution transfers the importance given to proprioceptive and visual inputs and the behavioral substitution refers to avoidance strategies e.g. immobilization, increased blink reflex and prevention of head rotations. Habituation on the other hand, accustoms the affected person to a conflicting situation, in order that the response of the VOR is avoided.

So far, it is known that previous conventional vestibular rehabilitation is effective for age-related vestibular loss. By improving vestibular function, the vestibular rehabilitation therapy aims to improve balance and neuromuscular coordination, minimize falls and decrease the feeling of dizziness.

However, new advances in technology have been made which generate additional methods for an effective therapy; exercise and videogaming, in short, exergaming. Successful use of virtual reality in rehabilitation of vestibular patients has previously been implemented. Further, recent evidence has examined the effects of exergaming in healthy dwellers on vestibular function. There was a significant reduction found in the dynamic visual acuity (DVA) after an eight-session exergame training (in total 160 minutes).

To date, the effects on vestibulo-ocular reflex of exergames in patients with chronic peripheral vestibular hypofunction have not been systematically explored. Moreover, very little is known about the effects of exergaming includes exercises requiring head turns on vestibular function in this patients. Furthermore, exergaming could become a new tool to improve DVA and dizziness and increase the training intensity without requiring many therapists, which in turn reduces health costs. In addition, patients with dizziness are severely affected by their disease. They will welcome new, efficient and motivating forms of therapy.Finally, the main aim is to assess the effects of virtual reality-based intervention with dividat "senso" on vestibular functions in patients with chronic peripheral unilateral vestibular hypofunction.