Browsing by Author "Hall, Courtney D."
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Item Oculomotor Strategies and Their Effect on Reducing Gaze Position Error(Otology & Neurotology, 2/1/2010) Schubert, Michael C.; Hall, Courtney D.; Das, Vallabh E.; Tusa, Ronald J.; Herdman, Susan J.Objective: Vestibular adaptation exercises have been shown to improve gaze stability during active head rotation in individuals with vestibular hypofunction. Little is known, however, of the types of eye movements used during passive head rotation and their effect on gaze stability in individuals with vestibular hypofunction. The primary purpose of this study was to determine differences in oculomotor strategies and their effect on stabilizing gaze during ipsilesional passive and active head rotations in vestibular hypofunction. Patients: Subjects with unilateral (n = 4) and bilateral (n = 3) vestibular hypofunction and healthy subjects (n = 4) based on bithermal caloric and rotational chair testing. Intervention: Diagnostic. Main Outcome Measure: Head and eye velocity and position data measured with scleral search coil. Results: Subjects with unilateral and bilateral vestibular hypofunction generated 3 types of gaze-stabilizing eye movements with ipsilesional head impulses: slow vestibular ocular reflex, compensatory, and corrective saccades. The types of eye movements generated during active and passive head impulses were highly individualized. Gaze position error was reduced when compensatory saccades were recruited as part of the gaze-stabilizing strategy. Conclusion: Rehabilitation for individuals with vestibular hypofunction should identify individuals' unique gaze stability preferences and attempt to facilitate compensatory saccades.Item Recovery of Dynamic Visual Acuity in Bilateral Vestibular Hypofunction(Archives of Otolaryngology Head and Neck Surgery, 4/1/2007) Herdman, Susan J.; Hall, Courtney D.; Schubert, Michael C.; Das, Vallabh E.; Tusa, Ronald J.Objective: To determine the effect of vestibular exercises on the recovery of visual acuity during head movement in patients with bilateral vestibular hypofunction (BVH). Design: Prospective, randomized, double-blinded study. Setting: Outpatient clinic, academic setting. Patients: Thirteen patients with BVH, aged 47 to 73 years. Intervention: One group (8 patients) performed vestibular exercises designed to enhance remaining vestibular function, and the other (5 patients) performed placebo exercises. Main: Outcome Measures Measurements of dynamic visual acuity (DVA) during predictable head movements using a computerized test; measurement of intensity of oscillopsia using a visual analog scale. Results: As a group, patients who performed vestibular exercises showed a significant improvement in DVA (P = .001), whereas those performing placebo exercises did not (P = .07). Only type of exercise (ie, vestibular vs placebo) was significantly correlated with change in DVA. Other factors examined, including age, time from onset, initial DVA, and complaints of oscillopsia and disequilibrium, were not significantly correlated with change in DVA. Change in oscillopsia did not correlate with change in DVA. Conclusions: Use of vestibular exercises is the main factor involved in recovery of DVA in patients with BVH. We theorize that exercises may foster the use of centrally programmed eye movements that could substitute for the vestibulo-ocular reflex. Trial Registration: clinicaltrials.gov Identifier: NCT00411216