Monzani D, Setti G, Marchioni D, Genovese E, Gherpelli C, Presutti L
ENT Clinic, Department of Neurosciences, Head-Neck and Rehabilitation, University Hospital of Modena, Italy.
Acta Otorhinolaryngol Ital. 2005 Aug;25(4):224-32.
One of the most recent and promising theoretical hypotheses for compensation of persistent asymmetry of dynamic vestibulo-ocular gain is sensory substitution. As a switch between oculomotor and vestibulo-ocular systems, saccadic eye movements are engaged in humans to compensate the angular displacement of the head towards the labyrinthine defective side thus preserving the foveal fixation of the target. This study focused on the possibility that saccadic eye movements might also compensate for the impaired vestibulo-spinal reflexes and force the postural system to a more effective control on upright stance and verified whether this sway-stabilizing effect could be applied to patients with vestibular disorders and balance dysfunction. In the first experiment, 27 patients with unilateral labyrinthine hypofunction, 24 patients with central vestibular disorders and 24 healthy volunteers were evaluated by static posturography in 3 different visual conditions: (a) eye open with fixation of a steady target, (b) eye closed, and (c) while performing horizontal visually-guided saccades. The percentage of individuals with a decreased body sway area during the oculomotor task was found to be higher in labyrinthine-defective patients as compared to those with central vestibular disorders and controls. In the second experiment, 46 patients with vestibular disorders both of central and peripheral origin, whose postural control improved by eye-tracking, as assessed by posturography, were later submitted to 12 consecutive training sessions based on repeated visually-guided saccades. Both the saccadic performances and postural control improved in all patients but a more pronounced effect was observed in those with peripheral vestibular disorders. Outcome of this rehabilitation technique was also corroborated by a general reduction of the perceived overall impairment from balance disorders as tested by a specific questionnaire.
对于持续性动态前庭眼动增益不对称的代偿，最新且有前景的理论假说是感觉替代。作为动眼系统和前庭眼动系统之间的一种转换机制，人类会通过眼球快速扫视运动来补偿头部向迷路功能缺陷侧的角位移，从而保持对目标的中央凹注视。本研究聚焦于眼球快速扫视运动是否也可能补偿受损的前庭脊髓反射，并促使姿势系统对直立姿势进行更有效的控制，并验证这种摇摆稳定效应是否适用于患有前庭疾病和平衡功能障碍的患者。在第一个实验中，通过静态姿势描记法在三种不同视觉条件下对27名单侧迷路功能减退患者、24名中枢性前庭疾病患者和24名健康志愿者进行了评估：(a) 睁眼并注视稳定目标；(b) 闭眼；(c) 进行水平视觉引导的眼球快速扫视运动。结果发现，与中枢性前庭疾病患者和对照组相比，迷路功能缺陷患者在动眼任务期间身体摇摆面积减小的个体百分比更高。在第二个实验中，对46名中枢性和外周性前庭疾病患者进行了研究，这些患者的姿势控制通过姿势描记法评估在眼动追踪时有所改善，随后他们接受了基于重复视觉引导眼球快速扫视运动的连续12次训练。所有患者的眼球快速扫视运动表现和姿势控制均有所改善，但在外周性前庭疾病患者中观察到的效果更为明显。通过一份特定问卷测试发现，平衡障碍导致的总体感知损伤普遍减轻，这也证实了这种康复技术的效果。
