Oculomotor Findings in Videonystagmography across the Lifespan.

Abstract

When performing oculomotor testing during standard videonystagmography (VNG), the vestibular system is not actively stimulated. Therefore, responses are generated from the cerebellum, brainstem, and oculomotor tract. Many patients seen for vestibular testing fall outside of the standard age norms, making it difficult to determine whether an abnormal finding is due to age or oculomotor dysfunction. The purpose of this study was to further evaluate the effect of age on a standard clinical VNG oculomotor test battery consisting of saccades, smooth pursuit, and optokinetic (OPK) testing. This is a cross-sectional, between-group prospective study comparing oculomotor tests between age groups. Twenty-one older adults between the ages of 60 and 90 years with no history of central or peripheral vestibular dysfunction were included in the study. Previously collected data from 29 children aged 4 to 6 years and 33 adults aged 20 to 60 years were also included. Participants completed oculomotor testing using infrared goggles consisting of saccades, smooth pursuit, and OPK. Statistical analyses were completed using multivariate analysis of variance and analysis of variance and follow-up analysis when indicated. Significant group differences were noted for saccade latency and speed, smooth pursuit gain, and OPK gain and speed. Children and older adults demonstrated longer saccade latencies compared with the controls, and older adults exhibited slower saccade speed than the controls and children. These results also indicated that smooth pursuit gain was reduced for children and older adults compared with controls, and gain decreased across all groups as frequency increased. Analyses of OPK results indicated older adults had reduced gain and speed compared with the children and control group. The findings of prolonged saccade latencies and reduced smooth pursuit gain in both children and older adults suggest possible cerebellar rather than attentional effects. However, other findings such as reduced saccade speed and reduced OPK gain were noted only in the older adults, which suggests oculomotor degeneration and/or insufficient coverage of the visual field during testing, respectively. These results also indicate the importance of age-specific normative data for use in clinical oculomotor testing.