Integrative and Adaptive Neurosciences Laboratory, UMR 7260 CNRS/Aix-Marseille University Marseille, France ; Service d'ORL et Chirurgie de la Face et du Cou, Assistance Publique Hopitaux de marseille, CHU Nord Marseille, France.
Integrative and Adaptive Neurosciences Laboratory, UMR 7260 CNRS/Aix-Marseille University Marseille, France.
Front Integr Neurosci. 2014 Jan 16;7:111. doi: 10.3389/fnint.2013.00111. eCollection 2013.
Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions, a result they have to be awarded of particularly when getting older.
姿势控制基于中枢对多感觉输入的整合，以及对身体在空间中朝向的内部表示。这种多感觉反馈调节姿势控制，并不断更新身体位置的内部模型，进而转发适应环境背景和约束的运动指令。前庭系统的外周定位靠近耳蜗，使得前庭系统损伤有可能在耳蜗植入（CI）手术后发生。如果 CI 患者存在前庭功能障碍，可能会对姿势稳定性产生强烈影响。在大多数日常生活条件下，CI 患者在进行简单的站立姿势任务时通常会与认知活动同时进行，因此在双重任务中会争夺注意力资源，并且在平衡功能受损的患者中跌倒的风险增加。本研究旨在评估成年聋人后天性耳蜗植入对姿势控制的影响。通过将患者的姿势表现与年龄匹配的健康受试者在静态（稳定平台）和动态（平移平台）条件下以及在进行视觉或听觉记忆任务的双重任务时进行的简单姿势任务进行比较，评估可能的前庭功能障碍。姿势测试在睁眼（EO）和闭眼（EC）条件下进行，CI 激活（ON）或不激活（OFF）。结果表明，CI 患者的姿势表现与对照组有很大不同，主要在 EC 条件下。CI 患者在静态条件下的稳定性极限明显降低，姿势不稳定增加。在动态条件下，他们花费更多的能量来保持平衡，他们的头部既不在空间中也不在躯干上稳定：他们在没有视觉的情况下像倒立摆一样动态地表现，而对照组则表现出全身刚性化策略。听力（佩戴助听器）和双重任务并不能真正改善 CI 患者的动态姿势表现。我们得出结论，CI 患者主要在具有挑战性的姿势条件下变得严重依赖视觉，这是他们在年龄增长时需要特别注意的结果。
