Background Patients with peripheral vestibular dysfunction often complain of dizziness, blurred vision, imbalance and etc. Vestibular rehabilitation although has been proved to be an efficient method to improve the symptoms, the optimal treatment type, intensity and frequency is still unclear. Base on the mechanisms of vestibular rehabilitation, vestibular adaptation, substitution, and habituation, repeated practice and exposure to symptom-provoked movement could improve the symptoms. However, the symptom-provoked movement generated by only head and eye movement might not create sufficient threshold to induce vestibulo-ocular reflex adaptation. Practicing vestibular exercises in the same environment might be difficult for the patients to transfer learned ability to the real world environment. Therefore, optokinetic stimulation could potentially provide stronger visual-vestibular mismatch, and when combining with a virtual reality system could also simulate real world environment. Furthermore, an intensive training protocol on a daily basis might possibly promote the mechanisms of vestibular rehabilitation to enhance recovery from peripheral vestibular lesions. The purpose of this study is to investigate the efficacy of an intense vestibular rehabilitation programme incorporated with optokinetic stimulation in virtual reality environment on both subjective and objective symptoms in patients with peripheral vestibular dysfunction in the short and long term.

Methods This study will be an assessor-blind randomised controlled trial. Patients diagnosed as peripheral vestibular dysfunction aged between 20-80 years will be recruited and randomly allocated into two groups: vestibular rehabilitation incorporated with optokinetic stimulation in virtual reality (Group OKN) and vestibular rehabilitation only (Group C). Group C will receive customised vestibular rehabilitation, while Group OKN will receive the same exercise programme as Group C plus optokinetic stimulation provided in virtual environment. Both groups will receive vestibular rehabilitation intensively for five consecutive days with a trained physiotherapist, following with daily home exercise for two months. Self-perceived symptoms, spatial orientation, postural control and gait performance will be assessed prior to treatment (baseline), at the end of the five-day treatment, at four and eight weeks following the five-day training.

Inclusion Criteria:

• diagnosed as peripheral vestibular dysfunction with bithermal caloric irrigation
• having one or more of the following subjective complains for longer than four weeks: vertigo/dizziness, disequilibrium, gait instability or motion sensitivity

Exclusion Criteria:

• central nervous system involvement
• active or poorly controlled migraine (more than one severe migraine a month)
• fluctuating symptoms e.g. Meniere's disease
• active benign paroxysmal positional vertigo (BPPV)
• have previous vestibular rehabilitation
• inability to attend sessions
• other medical conditions in the acute phase e.g. orthopaedic injury