Julia A Müller1, Christopher J Bockisch2, Alexander A Tarnutzer3. 1. Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland. 2. Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland; Department of Otorhinolaryngology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland; Department of Ophthalmology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland. 3. Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland. Electronic address: alexander.tarnutzer@access.uzh.ch.
Abstract
OBJECTIVE: Acute unilateral peripheral-vestibular hypofunction (UVH) shifts the subjective visual vertical (SVV) ipsilesionally, triggering central compensation that usually eliminates shifts when upright. We hypothesized that compensation is worse when roll-tilted. METHODS: We quantified SVV errors and variability in different roll-tilted positions (0°, ±45°, ±90°) in patients with chronic UVH affecting the superior branch (SVN; n=4) or the entire (CVN; n=9) vestibular nerve. RESULTS: Errors in SVN and CVN were not different. When roll-tilted ipsilesionally 45° (9.6±5.4° vs. -0.2±6.4°, patients vs. controls, p<0.001) and 90° (23.5±5.7° vs. 16.8±8.8°, p=0.003), the patient's SVV was shifted significantly towards the lesioned ear. When upright, only a trend was noted (3.6±2.2° vs. 0.0±1.2°, p=0.099); for contralesional roll-tilts shifts were not different from controls. Variability was larger for CVN than SVN (p=0.046). With increasing disease-duration, adjustment errors decayed for ipsilesional roll-tilt and upright (p⩽0.025). CONCLUSIONS: The reason verticality perception was distorted for ipsilesional roll-tilts, may be the insufficient integration of contralesional otolith-input. Similar errors in SVN and CVN suggest a dominant utricular role in verticality perception, albeit the sacculus may improve precision of SVV estimates. SIGNIFICANCE: With deficiencies in central compensation being roll-angle dependent, extending SVV-testing to roll-tilted positions may improve identifying patients with chronic UVH.
OBJECTIVE: Acute unilateral peripheral-vestibular hypofunction (UVH) shifts the subjective visual vertical (SVV) ipsilesionally, triggering central compensation that usually eliminates shifts when upright. We hypothesized that compensation is worse when roll-tilted. METHODS: We quantified SVV errors and variability in different roll-tilted positions (0°, ±45°, ±90°) in patients with chronic UVH affecting the superior branch (SVN; n=4) or the entire (CVN; n=9) vestibular nerve. RESULTS: Errors in SVN and CVN were not different. When roll-tilted ipsilesionally 45° (9.6±5.4° vs. -0.2±6.4°, patients vs. controls, p<0.001) and 90° (23.5±5.7° vs. 16.8±8.8°, p=0.003), the patient's SVV was shifted significantly towards the lesioned ear. When upright, only a trend was noted (3.6±2.2° vs. 0.0±1.2°, p=0.099); for contralesional roll-tilts shifts were not different from controls. Variability was larger for CVN than SVN (p=0.046). With increasing disease-duration, adjustment errors decayed for ipsilesional roll-tilt and upright (p⩽0.025). CONCLUSIONS: The reason verticality perception was distorted for ipsilesional roll-tilts, may be the insufficient integration of contralesional otolith-input. Similar errors in SVN and CVN suggest a dominant utricular role in verticality perception, albeit the sacculus may improve precision of SVV estimates. SIGNIFICANCE: With deficiencies in central compensation being roll-angle dependent, extending SVV-testing to roll-tilted positions may improve identifying patients with chronic UVH.