correlating vestibular results

correlating vestibular results - AudiologyOnline 2009 Page...

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AudiologyOnline 2009 Page 1 CORRELATING VESTIBULAR TEST FINDINGS Kamran Barin, Ph.D. Balance Disorders Clinic Department of Otolaryngology AudiologyOnline Live Seminar Wednesday, February 18, 2009 1 Some tests are functionally equivalent (e.g., gaze test without fixation and static position test without fixation) Contradictory findings in these tests indicate either a technical error or a rare or unusual finding Some tests provide complementary findings (e.g., caloric and rotation tests) Results from one test clarify interpretation of the other test Some tests evaluate overlapping but not necessarily identical parts of the balance system (e.g., tracking and fixation suppression tests) Results from these tests can be similar only if the test parameters are similar Correlations in Vestibular Function Tests 2 Since tracking and OPK findings are often overlapping, do they share the same central pathways? True OPK originates from retinal stimulation (requires full-field visual stimulation) and is a reflexive response Tracking originates from foveal stimulation (requires a small target) and is a voluntary response When the stimulus is a small target (as in a light bar), both tracking and OPK tests evaluate the same central pathways Full-field visual stimulation does not guarantee true OPK responses because both tracking (foveal) and OPK (retinal) receptors are stimulated True OPK testing requires removing foveal responses (optokinetic after-nystagmus test) Correlations in Tracking and OPK Tests
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AudiologyOnline 2009 Page 2 3 What about instructions to the patient in OPK? Look OPK nystagmus Stare OPK nystagmus Correlations in Tracking and OPK Tests 4 Can one test be normal and the other abnormal? Yes if the tests truly evaluate different pathways With a light bar, typically the results for OPK and tracking tests should be identical when equivalent test parameters are used In case of conflict, investigate more Correlations in Tracking and OPK Tests 5 Reduced OPK nystagmus intensity - Could be unilateral or bilateral, for all velocities or for high velocities only Correlations in Tracking and OPK Tests
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This note was uploaded on 04/11/2010 for the course AUD 831 taught by Professor Drlisakoch during the Spring '10 term at A.T. Still University.

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correlating vestibular results - AudiologyOnline 2009 Page...

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