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Effect of the Preset Angle

Waheeda Pagarkar, MRCPCH, MSc; Doris-Eva Bamiou, MSc, MPhil; Deborah Ridout, BSc(Hons), MSc; Linda M. Luxon, BSc(Hons), FRCP

Arch Otolaryngol Head Neck Surg. 2008;134(4):394-401.

Objectives  (1) To study the subjective visual vertical (SVV) and subjective visual horizontal (SVH) in patients with long-standing unilateral peripheral vestibular dysfunction (PVD) and unilateral Ménière's disease (MD) compared with controls. (2) To study the relationship between the direction of deviation of the linear marker (preset angle) and measures of SVV and SVH values.

Design  Prospective case-control study.

Setting  Outpatient clinic in a tertiary neuro-otology department.

Patients  Seventeen healthy volunteers (mean age, 35.5 years), 9 patients with PVD (mean age, 43.1 years), and 10 patients with MD (mean age, 50.7 years) were included in the analysis.

Interventions  All subjects had a detailed neuro-otological evaluation. Twelve replicate readings of SVV and SVH were taken for each subject, with random preset angles, 6 in the clockwise and 6 in the counterclockwise direction.

Main Outcome Measure  The SVV and SVH values were correlated with clinical features and the direction of the preset angle.

Results  The 2 subjects with PVD who had abnormal mean SVV and SVH values had symptoms of dysequilibrium and otolithic involvement. The 5 patients in the MD group who had abnormal mean SVV and SVH values had either recent acute vertiginous attacks or total canal paresis on the affected side. A previously unreported finding, to our knowledge, is that the SVV value depends on the direction of the preset angle in all subject groups, more so in the PVD and MD groups compared with controls. The SVV is inclined toward the direction of the preset angle. A weaker relation is seen between the SVH and preset angle.

Conclusion  The preset angle should be considered when comparing SVV and SVH values.

Author Affiliations: Department of Audiovestibular Medicine, Royal National Throat, Nose, and Ear Hospital (Dr Pagarkar), Department of Neuro-otology, National Hospital for Neurology and Neurosurgery (Drs Bamiou and Luxon), Department of Audiological Medicine (Drs Bamiou and Luxon), and Centre for Paediatric Epidemiology and Biostatistics (Ms Ridout), UCL Institute of Child Health, London, England.