Karnath H O, Ferber S, Dichgans J
Department of Cognitive Neurology, University of Tübingen, Germany.
Neurology. 2000 Nov 14;55(9):1298-304. doi: 10.1212/wnl.55.9.1298.
Stroke patients may exhibit the peculiar behavior of actively pushing away from the nonhemiparetic side, leading to lateral postural imbalance and a tendency to fall toward the paralyzed side. This phenomenon has been called the "pusher syndrome."
The current study analyzes the mechanism leading to contraversive pushing.
The subjective postural vertical (SPV) and subjective visual vertical (SVV) were determined in five consecutively admitted patients with severe contraversive pushing and in controls. Whereas adjustment of the SPV reflects the perceived upright orientation of the body, the SVV provides a sensitive and direction-specific measurement of peripheral and central vestibular dysfunction.
The deficit leading to contraversive pushing is an altered perception of the body's orientation in relation to gravity. Pusher patients experience their body as oriented "upright" when it is tilted 18 degrees to the nonhemiparetic, ipsilesional side. In contrast, perception of the SVV was undisturbed.
A separate pathway seems to be present in humans for sensing the orientation of gravity apart from the one for orientation perception of the visual world. This second graviceptive system decisively contributes to humans' control of upright body posture. Contraversive pushing occurring after stroke lesions may represent the behavioral correlate of a disturbed neural representation of this system.
中风患者可能会表现出一种特殊行为，即主动从非偏瘫侧推开，导致侧向姿势失衡，并倾向于向瘫痪侧跌倒。这种现象被称为“推者综合征”。
本研究分析导致反向推的机制。
对连续收治的5例严重反向推患者及对照组测定主观姿势垂直（SPV）和主观视觉垂直（SVV）。SPV的调整反映身体的感知直立方向，而SVV提供对外周和中枢前庭功能障碍的敏感且方向特异性的测量。
导致反向推的缺陷是对身体相对于重力方向的感知改变。推者患者在身体向非偏瘫同侧倾斜18度时仍感觉自己的身体是“直立”的。相比之下，SVV的感知未受干扰。
人类似乎存在一条独立于视觉世界方向感知途径的重力方向感知途径。这第二个重力感知系统对人类直立身体姿势的控制起决定性作用。中风损伤后出现的反向推可能代表该系统神经表征紊乱的行为关联。
