Affiliations: [a] Neuroscience Research Australia and the University of New South Wales, Sydney, Australia | [b] Department of Otolaryngology – Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA | [c] Royal North Shore Hospital, Sydney, Australia
Correspondence:
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Corresponding author: Dr. Americo A. Migliaccio, Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, 2031, Australia. Tel.: +61 2 9399 1030; Fax: +61 2 9399 1082; E-mail: a.migliaccio@neura.edu.au
Abstract: The head impulse test can be used to measure peripheral vestibular function of all six semicircular canals. Traditionally, vertical canal function is measured by rotating the head from a starting neutral position (forward facing) about a diagonal plane that bisects the sagittal and coronal planes. These types of head rotations elicit eye movements with large vertical and torsional (about the line of sight) angular velocity components. Three-dimensional (3D: horizontal, vertical and torsional) eye measurement techniques are needed to measure these velocity components. We wanted to determine whether 2D measurements coupled to a modified head impulse test are sufficient to measure function of all six canals. In this study we measured individual canal function in patients (n = 5) with peripheral unilateral hypofunction and control subjects (n = 4) using the traditional head impulse test and the 'gold standard' 3D (dual-coil) scleral search coil technique. We compared these results with those from our 2D modified head impulse test using the 2D coil technique (single-coil). We show that both techniques detect similar levels of asymmetrical function in patients and are equally accurate in isolating canals with hypofunction. We conclude that 2D eye measurement techniques, such as video pupil-tracking, can be used to test all six canals.
Keywords: Vestibulo-ocular reflex, 2D head impulse test, 2D and 3D scleral search coils, video-oculography
