This study is to evaluate the balance performance in unilateral vestibular loss (UVL) and bilateral vestibular loss (BVL) patients by using a new visual perturbation system including virtual reality (VR), Wii Balance Board (WBB), rubber foam, and a wearable accelerometer for body sway parameter quantification. Balance ability during 25s single leg stance was also assessed.

Forty-six normal subjects and 27 vestibular loss patients were recruited. Subjects were instructed to stand on WBB plus foam, and to wear a goggle delivering VR image. Two visual conditions were assessed: stable visual world (VR0.0) and perturbed visual world (VR0.1). Each condition lasted for 25s. Subjects wore one 3D accelerometer attached on the site of L5 vertebra. The balance performance was quantified by calculating the average “jerk” at X, Y, and Z axis during the test. Patients who fell during the test were removed from “jerk” analysis. The body sway was also measured during single leg stance at eye open and eye closed condition.

All normal subjects and patients completed VR0.0 without falling. No normal subjects fell at VR0.0; whereas 33% UVL patients and all BVL patients fell. At VR0.0, the average “jerk” in healthy subjects is 2.10±0.98 (min–max: 0.68–5.59), and in patients is 4.97±2.84 (min–max: 0.80–14.82). At VR0.1, the average “jerk” in normal subjects is 3.54±1.73 (min–max: 0.68–8.68), while in UVL patients is 10.62±4.70 (min–max: 1.10–16.33). In one leg stance test, the “jerk” was also significantly increased in UVL patients compared to normal subjects.

The new visual perturbation system and single leg stance test allows clinicians to efficiently evaluate balance performance and visual dependency at clinical settings. The body sway parameter “jerk” successfully distinguished vestibular deficit patients from healthy subjects. This system may be used in rehabilitation program to follow the improvement of balance performance in vestibular loss patients.