Abstract

BACKGROUND: The cervico-ocular reflex (COR) has been confirmed in numerous animal experiments. On the other hand, its clinical assessment is disputed. Anteflexion and retroflexion of the head are among the main movements of the atlanto-occipital joint. We investigated whether these head movements produce neck proprioceptive stimulation in the vestibular system.

SUBJECTS AND METHOD: We investigated 50 students under the experimental conditions of strictly cervical provocation. The trunk was rotated, anteflexed, and retroflexed into its end positions for 60 s under video-oculographic control without changing the head-space relationship. During the cervical provocation, horizontal, vertical, or rotational nystagmus within a time window of 5-30 s after the start of the provocation was detected as a target parameter.

RESULTS: The results showed that, compared to the baseline, there was a significant increase in vertical and horizontal nystagmus after the cervical provocation. The horizontal nystagmus reaction, rather than the vertical, was increased significantly by the maximum trunk rotation. In addition, we found a significant amount of vertical rather than horizontal nystagmus under trunk flexion provocation.

CONCLUSION: Under cervical provocation of test subjects, we were able to elicit horizontal and vertical nystagmus (upbeat nystagmus) via cervico-ocular roots. Due to a neck proprioceptive activation of the vestibular system we interpret our result as a "cervico-tonic provocation nystagmus".