Neck proprioception influence on vibration induced postural sway
Abstract
Rationale: Several reports have shown that the direction of the postural responses induced by vestibular stimulation is affected by the neck and torso position. The aim of the study was to investigate whether the postural responses to vibratory proprioceptive stimulation of the calf muscles are affected by the head position and thus by proprioceptive and vestibular information from the neck and head.
Material and Methods: Ten normal subjects were exposed to vibratory proprioceptive stimulation towards the calf muscles when the head was kept in five different positions; in a neutral position facing forwards, the head turned to the right or left side, or the head tilted backwards or forward. The body movements were evaluated by analyzing the anteroposterior and lateral torques induced towards the supporting surface.
Results: The analysis showed that only the anteroposterior body sway was significantly affected by the head position. The anteroposterior postural responses were primarily increased during the tests with tilted head backwards or forwards, whereas the postural responses were unaffected by head torsion towards the sides. The lateral responses were primarily affected by vision and not by the head position.
Conclusions: The findings suggest that the responses evoked by the vibratory proprioceptive stimulations of the calf muscles might be affected by different mechanisms, either by purely proprioceptive information or by an interaction between proprioceptive and vestibular information. Moreover, the increasing difference between the test conditions over time suggests that muscle fatigue of the neck muscles might be one of the factors affecting the responses induced by the perturbations.
