Goldberg G, Bloom K K
Department of Physiology Temple University School of Medicine Pennsylvania.
Am J Phys Med Rehabil. 1990 Oct;69(5):228-38. doi: 10.1097/00002060-199010000-00002.
The alien hand sign was first described by Brion and Jedynak as a "feeling of estrangement between the patient and one of his hands." The affected hand frequently shows a grasp reflex and an instinctive grasp reaction as well as elements of what Denny-Brown referred to as a "magnetic apraxia" associated with frontal lobe damage. Most notably, however, the affected hand is observed to perform apparently purposive behaviors that are perceived as being outside the volitional control of the patient. The patients interpret the behavior of their own affected limb as being controlled by an external agent. They do not feel that they are initiating or controlling the behavior of the hand and often express dismay at the hand's "extravolitional" activity. The patients attempt to control behavior of the alien hand with the unimpaired hand by forcibly restraining the affected limb, an act that may be termed "self-restriction." In this paper, we report an additional four cases of alien hand sign in right-handed subjects: two involving the right hand and two involving the left hand. In each case, the clinical findings were associated with extensive unilateral damage of the medial frontal cortex of the hemisphere contralateral to the affected hand. Furthermore, the alien movement gradually disappears over the course of 6-12 months after the stroke. These clinical case studies are presented and discussed in the context of the "dual premotoer systems hypothesis," an anatomicophysiological model that proposes that action is organized by two separate but interactive premotor brain systems corresponding to evolutionarily defined medial and lateral cortical moieties. It is hypothesized that the alien mode behavior results from unconstrained activity of the lateral premotor system in the damaged hemisphere. The residual volitional control in the limb occurs through the activity of the intact medial premotor system of the ipsilateral hemisphere. Recovery may occur through extension of these ipsilateral control mechanisms by compensatory changes in subcortical systems controlling hemispheric activation associated with adaptive behavior. This observation may be important in understanding mechanisms involved in motor recovery after stroke.
异己手征最初由布里昂和杰迪纳克描述为“患者与其一只手之间的疏离感”。受累手经常表现出抓握反射和本能抓握反应，以及丹尼-布朗所提及的与额叶损伤相关的“磁性失用症”的一些特征。然而，最值得注意的是，观察到受累手会做出明显有目的的行为，而患者感觉这些行为不受其意志控制。患者将自己受累肢体的行为解释为由外部因素控制。他们感觉自己并未发起或控制手的行为，并且常常对该手的“意志之外”的活动表示沮丧。患者试图用未受损的手通过强行约束受累肢体来控制异己手的行为，这一行为可称为“自我约束”。在本文中，我们报告了另外4例右利手受试者出现异己手征的病例：2例累及右手，2例累及左手。在每个病例中，临床发现均与受累手对侧半球内侧额叶皮质的广泛单侧损伤有关。此外，中风后6 - 12个月内，异己运动逐渐消失。这些临床病例研究是在“双运动前区系统假说”的背景下呈现和讨论的，该假说是一种解剖生理模型，提出动作由两个独立但相互作用的运动前脑系统组织，这两个系统分别对应于进化上定义的内侧和外侧皮质部分。据推测，异己模式行为是由于受损半球外侧运动前系统的无约束活动所致。肢体中残留的意志控制通过同侧半球完整的内侧运动前系统的活动实现。恢复可能通过控制与适应性行为相关的半球激活的皮质下系统的代偿性变化来扩展这些同侧控制机制而发生。这一观察结果对于理解中风后运动恢复所涉及的机制可能很重要。
