Affiliations: [a] Department of Otolaryngology-Head & Neck Surgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA | [b] Department of Physical Medicine and Rehabilitation, School of Medicine, Johns Hopkins University, Baltimore, MD, USA | [c] Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE, USA | [x] Otological and Skull Base Surgery Department, S.M. delle Scotte Hospital, Siena, Italy | [y] Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy
Correspondence:
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Corresponding author: Michael Schubert, 601 N. Caroline St, Rm 6245, Baltimore, MD 21127, USA. Tel.: +1 410 955 7381; Fax: +1 410 614 8610; E-mail: mschube1@jhmi.edu
Abstract: Background:Vestibular rehabilitation is a sub-specialization within the practice of physical therapy that includes treatments designed to reduce gaze instability. Gaze stability exercises are commonly given for head rotations to the left and right, even in subjects with one healthy vestibular system (as in unilateral loss). Few studies have investigated the difference in the angular vestibular ocular reflex gain (aVOR) measured in the acute phase after deafferentation for ipsilesional head rotations that move the head away from center or towards center. Objective:The purpose of this study was to compare differences in acute aVOR gain when the head was passively rotated outward from an initially centered position (neck neutral) versus the head being rotated inward. Methods:We recorded head and eye velocity using video head impulse test equipment in patients with unilateral vestibular pathology scheduled for tumor resection via retrosigmoid approach (n=5) or labyrinthectomy due to Meniere's disease (n=2). Results:We found 1) no difference in the ipsilesional aVOR gain for inward or outward directed head impulse rotations and 2) head velocity is inversely correlated with aVOR gain for ipsilesional but not contralesional rotations. Conclusions:Bedside testing of the ipsilesional aVOR following acute vestibular ablation can be done with head impulse rotations to either side. In the acute stages, physical therapists should prescribe ipsilesional and contralesional gaze stability exercises.
Keywords: Head impulse test, VOR gain, vestibular rehabilitation
