運用功能性電刺激恢復抓握功能之新電刺激模式
A Novel Functional Electrical Stimulation Method for the Restoration of Precision Grasping Functions
中文摘要
目前已有數種改善中風及脊髓損傷病患手部功能的功能性電刺激系統被發表或上市供病患使用，
其可分為兩大類：植入式功能性電刺激系統及表面式功能性電刺激系統。這兩類系統各有其優 缺點，基本功能上均可完成抓握及側夾的動作，而無法成功再生精細且常用的拿握動作卻是現 有系統的共同缺點。依電刺激的手部肌肉群來分析，這些功能性電刺激抓握系統大致上均以伸 指肌肉群、屈指肌肉群及姆指肌肉群為主要刺激標的肌肉。最近有學者研究發現，手內部肌肉群
（Intrinsic muscles）在完成手指伸張及縮屈動作上具有相當程度的輔助作用，而在目前功能 性電刺激的發展上，除了姆指掌肌肉群（Thenar muscles）外，少有人將其他手內部肌肉群 識為重要刺激標的。因此本研究便是針對手內部肌肉群，加以納入成為電刺激的標的肌肉，以 此新模式的功能性電刺激評估其手部抓握能力。
本研究是以兩個電刺激調節器（Respond II）及三對表面式電極貼片，配合新電刺激模式組成 簡易型表面式功能性電刺激器。此種電刺激模式的三對表面式電極貼片分別放置在：前臂外側、
前臂內側及手掌背面，利用電刺激器分別刺激伸指肌肉群、屈指肌肉群及手內部肌肉群，並加 上背側手腕固定副木以限制腕部活動，來完成抓握功能。評估方面，以ENRAF MYOMED 932 的電刺激模式來當作電刺激器，使用Cyber Glove 系統及 Biometrics 系統分別來量測刺激前 後關節角度及抓握力量的變化，並建立電流強度與關節角度及抓握力量之相關性；以抓握功能 測驗（GFT）來評估手部功能，包括抓握、拿握及夾握等的完成度。初步篩選五位健康受試者的 右手及一名中風病患的左手，接受新模式功能性電刺激，測試其刺激前後關節角度、抓握力量、
側夾力量、拿握力量及抓握能力，最後收集結果並加以探討。
結果發現，在新刺激模式下，五位健康受試者均能成功模擬各項抓握動作，其中四位在關節角 度及抓握力量的變化上亦都相當類似，並且在適當的”協同刺激”下均可順利完成抓握功能測 驗；該名中風病患的抓握力量變化的趨勢與正常受測者相似，但是對電刺激強度的敏感性及抓 握力量強度的大小，明顯不如正常人，肌肉疲乏的速度亦較正常人快，可能與長期失用導致肌 肉萎縮有關。結論認為，以手內部肌肉群為重要電刺激標的的新電刺激模式，的確可輔助完成 手部抓握、側夾及精細的拿握功能，對將來架構上肢表面式功能性電刺激抓握系統會有相當大 的幫助。
英文摘要
Those quadriplegics or hemiplegics who lost their grasp function cannot
independently perform activities of daily life (ADL), such as eating, drinking, writing, etc. Being unable to perform these activities independently, the quality of life of the patients is much degraded and it may increase the loading to their families both economically and psychologically. As many researches showed that functional electrical stimulation (FES) can be used to restore hand function of cervical level
spinal cord injury (SCI) and stroke patients. This is achieved by coordination between thumb and other four fingers movement. However, those FES systems still remain many defects which need to be modified for an ideal grasping system. Several studies had investigated the function of the hand intrinsic muscles for grasping. They found that electrical stimulation (ES) of the hand intrinsic muscles may be useful for improving grasp function of disabilities. Therefore, it is our main goal to develop a new ES model by including the hand intrinsic muscles as stimulating target muscles for quadriplegics and hemiplegics, to improve their quality of life by restoration of grasp function.
We took two ES regulator and stimulator (Respond II) and three paired surface electrodes to set up a simple surface FES system. A wrist fixation splint was custom- made for restriction of wrist motion. The stimulating target sites for generating grasp function of our ES model were dorsal side of forearm (finger extensor muscles group), volar side of forearm (finger flexor muscles group) and dorsal side of hand (hand intrinsic muscles group). In outcome measures, we designed three evaluation tests: range of motion (ROM) test, grasp force test and grasp function test (GFT). At first, we used Cyber Glove system to record range of motion (ROM) of subjects’
hands which was elicited by ES. The second test, we used dynamometer of Biometrics system to detect the grasp and pinch forces which were activated by stimulation of flexor or hand intrinsic muscles. The relationship between intensity of ES and ROM or grasp force was also investigated. The third test, grasp function test (include spherical grip, cylinder grip, precision grip, lateral pinch and tapping) was evaluated by using ordinary stuff such as: Small ball, cup, bottle, small cube, pen, floppy disc and telephone. We included five healthy volunteers and one stroke patient for this study.
New ES model FES system was applied in all volunteers’ hands successfully. The movement patterns of hands were similar in all subjects during electrical stimulation of each muscles group. After optimal adjustment of ES intensity and duration for co- contraction of those three muscles groups, each subject could do all grasp function task (GFT) smoothly. Especially, precision grasp could be induced by electrically co- activation of intrinsic muscles and finger flexor muscles to use pen and take a cube.
Muscle strengths were also enough to perform ADL in all subjects. But, the sensitivity and force generation of patient’s hand were small than normal subjects significantly. Those might related with disuse atrophy of paralyzed hand of this stroke patient. Finally, we concluded, the primary application of the novel ES model is quite successful for restoring grasp function in normal subjects and disability subjects. It will be very helpful to build a new surface FES grasp system for disability patients in the future.
