Di Fabio R P, Emasithi A
Department of Physical Medicine and Rehabilitation, University of Minnesota, UMHC, Minneapolis 55455, USA.
Phys Ther. 1997 May;77(5):458-75. doi: 10.1093/ptj/77.5.458.
The quality of sensory information that is necessary for balance and postural stability will depend to a great extent on head stability as the body moves. How older persons coordinate head and body motion for balance during volitional activities is not known. The purposes of this article are to present a basis for understanding the influence of aging on head control during voluntary motion and to discuss some data that demonstrate how elderly people might control head movement to improve gaze and the quality of vestibular inputs. A "top-down" or "head-first" control scheme is proposed as the mechanism that elderly people without disabilities use to maintain head position during self-initiated motion. This type of control ensures that the angular position of the head in space remains relatively constant--through the use of a head-stabilization-in-space (HSS) strategy--regardless of the magnitude or direction of displacements in the body's center of force. The HSS strategy is thought to reduce potential ambiguities in the interpretation of sensory inputs for balance and is derived primarily from a geocentric (orientation to the vertical) frame of reference. Egocentric (orientation of the head with respect to the body) or exocentric (orientation to objects in the environment) frames of reference, however, refine the control of head stabilization. Preliminary research suggests that elderly people use the HSS strategy to control head pitch during difficult balance tasks. These findings, if supported by more definitive studies, may be useful in the treatment of patients with balance disorders. The treatment of patients with balance dysfunction is discussed within the conceptual framework of a "head-first" organization scheme.
平衡和姿势稳定性所需的感觉信息质量在很大程度上取决于身体移动时头部的稳定性。目前尚不清楚老年人在自主活动中如何协调头部和身体运动以保持平衡。本文的目的是提供一个基础，以理解衰老对自主运动中头部控制的影响，并讨论一些数据，这些数据展示了老年人如何控制头部运动以改善注视和前庭输入的质量。本文提出了一种“自上而下”或“头部优先”的控制方案，作为无障碍老年人在自主运动中保持头部位置的机制。这种类型的控制通过使用空间头部稳定（HSS）策略，确保头部在空间中的角位置保持相对恒定，而不管身体力中心位移的大小或方向如何。HSS策略被认为可以减少平衡感觉输入解释中的潜在模糊性，并且主要源自地心（相对于垂直方向的定向）参考系。然而，以自我为中心（头部相对于身体的定向）或以外界为中心（相对于环境中物体的定向）的参考系可以完善头部稳定的控制。初步研究表明，老年人在困难的平衡任务中使用HSS策略来控制头部俯仰。如果这些发现得到更确切研究的支持，可能对平衡障碍患者的治疗有用。本文在“头部优先”组织方案的概念框架内讨论了平衡功能障碍患者的治疗。
