Eye movement responses to active, high-frequency pitch and yaw head rotations in subjects with unilateral vestibular loss or posterior semicircular canal occlusion
Affiliations: Neurotology Research, Legacy Clinical Research and Technology Center, Portland, OR, USA
Correspondence:
[*]
Corresponding author: Claire Poulin, Neurotology Research, Legacy Clinical Research and Technology Center, 1225 NE 2nd Avenue, Portland, OR 97208, USA. Tel.: +1 503 413 5342; Fax: +1 503 413 5348; E-mail: clairep@lhs.org
Abstract: This study assessed the eye movement responses to active head rotation in six subjects with complete unilateral vestibular loss (UVL), five subjects with posterior canal plugging (PCP) and age- and sex-matched normal subjects. Subjects performed head rotations in the pitch and yaw planes at frequencies ranging from 2 to 6 Hz, while looking at an earth-fixed target. Vertical eye movement gains obtained in UVL, PCP and normal subjects were not significantly different. Vertical phases decreased with increasing head movement frequencies in both UVL and PCP subjects. Although this decrease produced significantly different vertical phases between UVL and normal subjects for head movements above 3.9 Hz, vertical phases in some normal subjects were similar to those obtained in UVL subjects. We conclude that active head oscillations in the pitch plane are not clinically useful for the detection of vertical canal impairment limited to one ear. As expected, UVL subjects showed reduced horizontal gains, and eye velocity asymmetries during active head rotation in the yaw plane. Results in some PCP subjects suggested possible minor impairments of horizontal vestibulo-ocular reflexes.
Keywords: vestibular, active head rotation, posterior canal, unilateral, human
