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Normal Responses

Meeli Hirvonen, MD; Heikki Aalto, PhD; Americo Aniello Migliaccio, PhD; Timo Petteri Hirvonen, MD, PhD

Arch Otolaryngol Head Neck Surg. 2007;133(2):157-161.

Objective  To characterize the horizontal angular vestibulo-ocular reflex using a new motorized head impulse rotator and electro-oculography technique.

Design  Prospective case-control study.

Participants  We included 22 healthy volunteers with unpredictable, horizontal motorized head impulses with a mean velocity of 170°/s and a mean acceleration of 1550°/s². We recorded head and eye position and calculated gain, asymmetry, and latency of the vestibulo-ocular reflex. All subjects underwent testing twice while viewing a far (140 cm) target to evaluate the repeatability of the measurement. In addition, 8 of these subjects underwent testing while viewing a near (15 cm) target. We reported findings as mean ± SD.

Results  The mean gain during the 30-millisecond interval before peak head velocity and during the interval when head velocity ranged from 100°/s to 120°/s was 1.08 ± 0.10. The mean asymmetry in gain between sides was 3.7% ± 2.8%, and the mean latency of the vestibulo-ocular reflex was 3.4 ± 6.3 milliseconds. There was a statistically significant correlation between consecutive gain measurements for each subject (r = 0.59; P=.004). The mean gain for the near target was 1.26 ± 0.10 and was significantly higher than that for the far target (P=.002).

Conclusions  The vestibulo-ocular reflex measurements using our novel system are comparable to those achieved using other techniques. These results suggest that a motorized head impulse rotator with electro-oculography allows reliable and fast measurement of the vestibulo-ocular reflex. In addition, the method is safe, repeatable, and thus could be a useful tool in the clinical assessment of the vestibulo-ocular reflex.

Author Affiliations: Department of Otolaryngology, Helsinki University Central Hospital, Helsinki, Finland (Drs M. Hirvonen, Aalto, and T. P. Hirvonen); and Department of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Md (Dr Migliaccio).