Vestibulo-ocular, optokinetic and postural function in humans with rheumatoid arthritis

The present study investigated vestibulo-ocular reflex (VOR), optokinetic reflex (OKR) and postural function in patients with rheumatoid arthritis (RA). Compared with controls, no differences in gaze-holding, VOR gain or phase, OKR slow phase velocity (SPV) or quick phase amplitude, optokinetic afternystagmus SPV or duration, or latency to the illusion of circularvection, were found. RA patients did exhibit greater sway in the leftward direction (P<0.01), however, this was no greater in the conditions of the Clinical Test of Sensory Interaction and Balance that increase reliance upon vestibular information. We conclude that RA patients do not exhibit substantial deficits in visual-vestibular function.

Optokinetic reflex dysfunction in multiple sclerosis

The aim of this study was to further investigate optokinetic reflex function in multiple sclerosis. Gaze-holding in darkness, optokinetic nystagmus, optokinetic afternystagmus and latency to circularvection were measured using electro-oculography and a rotating optokinetic drum. Gaze-holding was not significantly different between the multiple sclerosis and control groups; however, four of 23 multiple sclerosis patients exhibited eccentric gaze-evoked nystagmus. There were no significant differences in either optokinetic nystagmus frequency or latency to circularvection. However, optokinetic nystagmus slow phase velocity during rise time and amplitude during beat time were significantly reduced in the multiple sclerosis group (p < 0.05 and p < 0.0001, respectively). The time constant of optokinetic afternystagmus was also significantly reduced in the multiple sclerosis group (p < 0.005). These results indicate that optokinetic nystagmus and optokinetic afternystagmus are significantly impaired multiple sclerosis.