Browsing by Author "Garrison, Doug"
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Item Open Access Relationship Between Corrective Saccades and Measures of Physical Function in Unilateral and Bilateral Vestibular Loss.(Ear and hearing, 2020-05-21) Riska, Kristal M; Bellucci, Jordan; Garrison, Doug; Hall, CourtneyOBJECTIVES:Following the loss of vestibular function, some patients functionally improve and are minimally bothered by their loss of peripheral function while others remain more symptomatic and are unable to return to their activities of daily living. To date, the mechanisms for functional improvement remain poorly understood. The purpose of the present study was to examine the association between corrective saccades and measures of handicap, dynamic visual acuity, gait, and falls. DESIGN:A retrospective chart review was performed to identify patients who were diagnosed with unilateral or bilateral vestibular hypofunction and who also completed a baseline vestibular rehabilitation evaluation. A total of 82 patients with unilateral vestibular hypofunction and 17 patients with bilateral vestibular hypofunction were identified. The video head impulse test results for each patient were grouped based on the type of presenting saccades. Specifically, the saccade grouping included the following: (1) covert, (2) overt, or (3) a combination of both types of saccades. RESULTS:The results show that covert saccades are associated with better performance on measures of dynamic visual acuity, gait, and balance in patients with unilateral vestibular hypofunction. Patients exhibiting overt saccades or combination of both covert and overt saccades were more often found to have an abnormal gait speed and be characterized as being at risk for falls using the Dynamic Gait Index. We observed no differences in physical function for those patients with bilateral vestibular hypofunction as a function of saccade grouping. CONCLUSIONS:When comparing saccade groups (covert, overt, or combination of both), patients with unilateral vestibular hypofunction and covert saccades demonstrated better performance on standard baseline physical therapy measures of dynamic visual acuity and gait and balance. We did not observe any significant associations between saccade group and physical function in patients with bilateral vestibular hypofunction; however, additional studies are needed with adequate sample sizes. Our findings may suggest that corrective saccade latency in patients with unilateral vestibular hypofunction is related to measures of physical function. The extent to which saccade latency has the potential to be a useful target for vestibular rehabilitation is still to be determined and may be promising target to improve functional outcomes.Item Open Access Vestibular function after cochlear implantation: A test battery and case-by-case approach.(Laryngoscope Investigative Otolaryngology, 2020-06-04) Piker, Erin G; Riska, Kristal; Garrison, Doug; Kaylie, David MObjectives:The purpose of this study was to assess the effects of cochlear implantation on the functional integrity of the horizontal semicircular canal using multiple methodologies, and to discuss and highlight the limitations of using isolated vestibular tests to assess vestibular function in surgical ears. Methods:Ten cochlear implant patients were consented to undergo a preoperative and 3-month postoperative vestibular assessment. The horizontal semicircular canal (SCC) was assessed using three different vestibular test measures that assess function using different stimuli and at different frequencies ranges: caloric testing, sinusoidal harmonic acceleration testing in the rotary chair, and video head impulse testing in the plane of the horizontal SCC. Data was analyzed using different methods: descriptive, statistical, and by an examination of individual case studies. Results:Each analysis method yielded a different interpretation. Statistical analysis showed no significant group mean differences between baseline pre-op vestibular test results and 3-month post-op vestibular test results. Descriptive analysis showed 30% of individuals presented with postoperative abnormal vestibular testing findings. A case study examination showed that only one patient presented with a post-op decrease in vestibular function in the implanted ear. Conclusions:There are several limitations of conventional vestibular testing in postsurgical cochlear implant patients. A test-battery approach, including case history, and test interpretation made on a case-by-case basis is needed to determine whether the patient has undergone vestibular damage, is at risk for falling, or in need of further management. Level of Evidence:2b individual cohort study.