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Recovery of dynamic visual acuity in unilateral vestibular hypofunction
Susan J Herdman1, Michael C Schubert, Vallabh E Das
1Department of Rehabilitation Medicine, Emory University, Atlanta, Ga., USA. sherdma@emory.edu
Objective:
To determine the effect of vestibular exercises on the recovery of visual acuity during head movement in patients with unilateral vestibular hypofunction.
Study Design:
Prospective, randomized, double-blind study.
Setting:
Ambulatory referral center.
Patients:
Twenty-one patients with unilateral vestibular hypofunction, aged 20 to 86 years.
Intervention:
One group (13 patients) performed vestibular exercises designed to enhance the vestibulo-ocular reflex, and the other group (8 patients) performed placebo exercises. The placebo group was switched to vestibular exercises after 4 weeks.
Outcome Measures:
Measurements of dynamic visual acuity (DVA) during predictable (DVA-predictable) and unpredictable (DVA-unpredictable) head movements by means of a computerized test and measurement of intensity of oscillopsia by means of a visual analog scale.
Results:
As a group, patients who performed vestibular exercises showed a significant improvement in DVA-predictable (P<.001) and DVA-unpredictable (P<.001), while those performing placebo exercises did not (P =.07). On the basis of stepwise regression analysis, the leading factor contributing to improvement was vestibular exercises. This reached significance for DVA-predictable (P =.009) but not DVA-unpredictable (P =.11). Other factors examined included age, time from onset, initial DVA, oscillopsia, and duration of treatment. Changes in oscillopsia did not correlate with DVA-predictable or DVA-unpredictable.
Conclusions:
Use of vestibular exercises is the main factor involved in recovery of DVA-predictable and DVA-unpredictable in patients with unilateral vestibular hypofunction. Exercises may foster the use of centrally programmed eye movements that could substitute for the vestibulo-ocular reflex. The DVA-predictable would benefit more from this than would DVA-unpredictable.