Neck proprioception and spatial orientation in

Neck muscle vibration is known to influence body orienta-tion and posture during locomotion and stance in normal subjects. To verify the hypothesis that neck proprioceptive input can be misinterpreted in patients with cervical dys-tonia (CD), lateral continuous vibration was applied to the sternocleidomastoid muscle during both stepping-in-place and quiet stance, with eyes closed. The orienting responses of CD patients were compared with those of normal sub-jects. Vibration effects on body orientation during step-ping and stance were apparently different from normal, since no effects were seen when all patients ’ data collapsed were analysed. However, while some patients did not respond to vibratory stimuli regardless of the vibrated side, others had a ‘good ’ side, the stimulation of which produced effects on body orientation similar to thos