Jaeger R J
Pritzker Institute of Medical Engineering, Illinois Institute of Technology, Chicago 60616.
Assist Technol. 1992;4(1):19-30. doi: 10.1080/10400435.1992.10132189.
Functional electrical stimulation (FES) applications in the lower extremity are common in research laboratories, but clinical applications are minimal. This review summarizes current knowledge with respect to clinical application. When electrical stimulation is used in clinical applications for functional movement such as standing and walking, it is typically applied in an open-loop manner; a predetermined stimulus pattern is delivered regardless of the consequences of the actual movement. Few clinical applications of FES involve closed-loop control because of the numerous difficulties involved in its application. As with any volitional muscle contraction, electrically stimulated muscle contractions will exhibit fatigue. Although the dynamics of fatigue may differ, electrically stimulated muscle contractions cannot be continuously sustained, and if the duty cycle is too severe, even alternating periods of rest and contraction cannot be sustained at a constant force level. The exact nature of fatigue is highly specific to the past history of the individual muscle and to the individual subject. Despite their intricate detail, quantitative modeling studies have not yet been applied extensively to clinical applications. Present implantable systems are not yet a viable option for clinical application. It is not clear whether more success with surface or percutaneous systems must first be achieved to justify implantation or whether greater improvements in implantable technology and surgical protocols are needed before implantable systems will become practical. It is clear that almost any reasonably designed stimulation protocol will increase muscle bulk. The existence of other therapeutic benefits and their cost/benefit ratios remain to be fully established. It is possible to stand through bilateral stimulation of the quadriceps. Using surface electrodes, this technique is achievable in any physical therapy clinic having minimal expertise in neuromuscular stimulation. FES-aided standing must be conducted as a research project with a protocol approved by the local institutional review board, as there are currently no FDA-approved stimulation devices for standing. Multichannel FES systems are not currently available for clinical application in the United States. This may change if the "Parastep" system receives FDA approval. Percutaneous and implanted systems are years away from commercialization and clinical availability. Hybrid systems, based primarily on the reciprocating gait orthosis (RGO), are presently the only clinically available form of walking that includes some form of FES assistance. The costs and benefits of adding FES to the RGO and the long-term user acceptance rate for these systems remain to be determined.
功能性电刺激（FES）在下肢的应用在研究实验室中很常见，但临床应用却很少。本综述总结了有关临床应用的现有知识。当电刺激用于诸如站立和行走等功能性运动的临床应用时，通常以开环方式应用；不管实际运动的结果如何，都会传递预定的刺激模式。由于FES的应用涉及诸多困难，其临床应用很少涉及闭环控制。与任何随意性肌肉收缩一样，电刺激的肌肉收缩会出现疲劳。尽管疲劳的动态可能有所不同，但电刺激的肌肉收缩无法持续维持，如果占空比过于严重，即使是休息和收缩的交替期也无法在恒定的力水平上维持。疲劳的确切性质高度取决于单个肌肉的既往历史和个体受试者。尽管定量建模研究细节复杂，但尚未广泛应用于临床应用。目前的可植入系统还不是临床应用的可行选择。尚不清楚是否必须首先在表面或经皮系统上取得更大成功才能证明植入的合理性，或者在可植入系统变得实用之前，是否需要在可植入技术和手术方案方面取得更大改进。显然，几乎任何合理设计的刺激方案都会增加肌肉量。其他治疗益处的存在及其成本效益比仍有待充分确定。通过双侧刺激股四头肌可以实现站立。使用表面电极，这种技术在任何对神经肌肉刺激有最低专业知识的物理治疗诊所都可以实现。由于目前没有FDA批准的用于站立的刺激设备，FES辅助站立必须作为一个研究项目进行，其方案需经当地机构审查委员会批准。多通道FES系统目前在美国尚不可用于临床应用。如果“Parastep”系统获得FDA批准，这种情况可能会改变。经皮和植入系统距离商业化和临床应用还有数年时间。主要基于往复式步态矫形器（RGO）的混合系统目前是唯一临床可用的包括某种形式FES辅助的行走方式。将FES添加到RGO的成本效益以及这些系统的长期用户接受率仍有待确定。
