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 propriocepti on and the vestibulo-ocular reflex (VOR), we rotated 16 healthy subjects bo th facing forward and with their heads passively turned 70 degrees to eithe r side. We found that gain tended to be lower a hen the subjects a ere rota ted with their heads turned opposite to the direction of rotation compared to when they were rotated in the same direction, but facing forward. Althou gh our findings were not statistically significant, they suggest that there is a measurable interaction between neck proprioception and the VOR in sub jects with normal vestibular function. Asymmetric neck muscle proprioceptiv e 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, thi s could lead to misinterpretation of vestibular assessments in patients wit h neck pain who also complain of dizziness.