Affiliations: [a]
Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria
| [b]
Department of Otolaryngology, Petz Aladár Teaching Hospital, Györ, Hungary
| [c] Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, Australia
| [d] Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland | [e]
Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland | [f]
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| [g]
Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA
| [h]
School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
Correspondence:
[*]
Corresponding author. Americo A. Migliaccio, Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia. E-mail: [email protected].
Note: [1] Authors contributed equally.
Abstract: BACKGROUND:The gain (eye-velocity/head-velocity) of the angular vestibuloocular reflex (aVOR) during head impulses can be increased while viewing near-targets and when exposed to unilateral, incremental retinal image velocity error signals. It is not clear however, whether the tonic or phasic vestibular pathways mediate these gain increases. OBJECTIVE:Determine whether a shared pathway is responsible for gain enhancement between vergence and adaptation of aVOR gain in patients with unilateral vestibular hypofunction (UVH). MATERIAL AND METHODS:20 patients with UVH were examined for change in aVOR gain during a vergence task and after 15-minutes of ipsilesional incremental VOR adaptation (uIVA) using StableEyes (a device that controls a laser target as a function of head velocity) during horizontal passive head impulses. A 5 % aVOR gain increase was defined as the threshold for significant change. RESULTS:11/20 patients had >5% vergence-mediated gain increase during ipsi-lesional impulses. For uIVA, 10/20 patients had >5% ipsi-lesional gain increase. There was no correlation between the vergence-mediated gain increase and gain increase after uIVA training. CONCLUSION:Vergence-enhanced and uIVA training gain increases are mediated by separate mechanisms and/or vestibular pathways (tonic/phasic). The ability to increase the aVOR gain during vergence is not prognostic for successful adaptation training.
