• Vestibular function: caloric test (pre-intervention); rotary chair test (pre- and post-intervention)
• Subjective complaints: (all pre- and post-intervention):
• disability scale
• activities specific balance confidence scale
• symptoms intensity for dizziness, oscillopsia, disequilibrium
• Balance and Gait
• fall risk (Dynamic Gait Index)
• Eye movements: scleral search coil

The purpose of this study is to determine whether exercises relieve the symptoms of dizziness and imbalance in people with vestibular deficits and improves the ability to see clearly during head movements. We hypothesize that the performance of specific adaptation and substitution exercises will result in an improvement in visual acuity during head movements while those patients performing placebo exercises will show no improvement.

Decrements in visual acuity during head movement in patients with vestibular hypofunction are potentially serious problems. This deficit could contribute to decreased activity level, avoidance of driving with resultant diminished independence and, ultimately, limited social interactions and increased isolation. Oscillopsia occurs because of inadequate vestibulo-ocular reflex (VOR) gain and suggests that compensation for the vestibular loss has not occurred. The purpose of this study was to examine the effect of an exercise intervention on visual acuity during head movement in patients with unilateral and bilateral vestibular hypofunction. We hypothesized that 1) patients performing vestibular exercises would have improved visual acuity during head movement compared to patients performing placebo exercises; 2) there would be no correlation between dynamic visual acuity (DVA) and the patients’ subjective complaints of oscillopsia; and 3) improvement in DVA would be reflected by changes in residual vestibular function as indicated by an increase in VOR gain.

Patients are assigned randomly to either the vestibular exercise or placebo exercise group. The randomization schedule is generated using a computer program for 2-sample randomization. The sequence was not concealed from the investigator who obtained consent from the subjects and supervised the exercises (SJH). The group assignment (vestibular exercise or placebo exercise) was concealed from the participants and from the investigator who performed the outcome measures.

The vestibular exercise group practiced exercises that consisted of adaptation exercises and eye-head exercises to targets (Table 1), which were designed to improve gaze stability 16. They also performed gait and balance exercises. The placebo exercise group performed exercises designed to be ‘vestibular-neutral’.

• Unilateral Vestibular Hypofunction
• Bilateral Vestibular Hypofunction

• Behavioral: vestibular exercises
• Behavioral: Vestibular neutral exercises

• Herdman SJ, Tusa RJ, Blatt P, Suzuki A, Venuto PJ, Roberts D. Computerized dynamic visual acuity test in the assessment of vestibular deficits. Am J Otol. 1998 Nov;19(6):790-6.
• Herdman SJ, Schubert MC, Tusa RJ. Role of central preprogramming in dynamic visual acuity with vestibular loss. Arch Otolaryngol Head Neck Surg. 2001 Oct;127(10):1205-10.
• Schubert MC, Herdman SJ, Tusa RJ. Functional measure of gaze stability in patients with vestibular hypofunction. Ann N Y Acad Sci. 2001 Oct;942:490-1. No abstract available.
• Schubert MC, Herdman SJ, Tusa RJ. Vertical dynamic visual acuity in normal subjects and patients with vestibular hypofunction. Otol Neurotol. 2002 May;23(3):372-7.
• Herdman SJ, Schubert MC, Das VE, Tusa RJ. Recovery of dynamic visual acuity in unilateral vestibular hypofunction. Arch Otolaryngol Head Neck Surg. 2003 Aug;129(8):819-24.
• Schubert MC, Das V, Tusa RJ, Herdman SJ. Cervico-ocular reflex in normal subjects and patients with unilateral vestibular hypofunction. Otol Neurotol. 2004 Jan;25(1):65-71.
• Hall CD, Schubert MC, Herdman SJ. Prediction of fall risk reduction as measured by dynamic gait index in individuals with unilateral vestibular hypofunction. Otol Neurotol. 2004 Sep;25(5):746-51.
• Herdman SJ, Hall CD, Schubert MC, Das VE, Tusa RJ. Recovery of dynamic visual acuity in bilateral vestibular hypofunction. Arch Otolaryngol Head Neck Surg. 2007 Apr;133(4):383-9.

Inclusion Criteria:

• Patient had to have either a unilateral vestibular or bilateral vestibular hypofunction defined as follows: Unilateral vestibular deficits were defined by a > 25% difference in slow phase eye velocity between right and left sides on either the caloric or rotary chair test. Bilateral vestibular deficits were defined included refixation saccades made in response to unpredictable head thrusts to the right and left, a gain < .1 on rotary chair step test and a peak slow phase eye movement of <5 degrees/sec during irrigation of each ear on bithermal water caloric testing
• Healthy subjects with normal vestibular function test results
• must be able to complete DVA test

Exclusion Criteria:

• Patients with central lesions will be omitted from the study because vestibular adaptation or other compensatory mechanisms may be compromised and
• Patients with visual acuity when the head is stationary of 20/60 or worse.
• Patients on medication that suppress or facilitate vestibular function will not be excluded from the study but data will be analyzed to assess the effect of medication.
• Patient who do not understand the purpose of the study and what it involves