Passive sustained turning of the head induces asymmetric gain of the vestibulo-ocular reflex in healthy subjects

In order to test the hypothesis of an interaction between neck proprioception and the vestibulo-ocular reflex (VOR), we rotated 16 healthy subjects both facing forward and with their heads passively turned 70 degrees to either side. We found that gain tended to be lower when the subjects were rotated with their heads turned opposite to the direction of rotation compared to when they were rotated in the same direction, but facing forward. Although our findings were not statistically significant, they suggest that there is a measurable interaction between neck proprioception and the VOR in subjects with normal vestibular function. Asymmetric neck muscle proprioceptive signals seem to give rise to asymmetric functioning of the VOR, which, at least in part, could be the pathogenesis of cervical dizziness. If so, this could lead to misinterpretation of vestibular assessments in patients with neck pain who also complain of dizziness.