脊髓與周邊神經調控對經皮電刺激誘發肌肉收縮力量影響之研究

Investigation of spinal and peripheral modulation of forces evoked by transcutaneous neuromuscular electrical stimulation

陳俊凡(CHIUN-FAN CHEN)

指導教授 ： 郭德盛 ； 賴金鑫

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.02535

摘要

電刺激(electrical stimulation)的應用主要在於誘發神經肌肉系統產生如同自主肌肉收縮般的運動(voluntary contraction)以提升肌力或延緩肌肉萎縮現象。由於自主性的肌肉收縮常伴隨來自中樞與周邊神經系統(central and peripheral nervous system)的綜合效應，因此本文將論述多個研究步驟以評估該效應所可能產生之各種現象。首先，將以紐西蘭白兔對應同一脈波電荷(electric charge)與能量(electrical energy)所產生之單一收縮(twitch force)一致性做為電刺激對周邊效應的一個評估基準，再以頻率或強度調變(frequency and intensity modulation)爆叢(burst)的方式，分析爆叢前後之強直收縮(tetanic force)改變值做為電刺激對周邊與中樞綜合效應的另一評估基準，而隨後並執行中樞神經系統之阻斷(nerve block)以及重複前述步驟以取得純周邊效應等資訊。周邊效應的評估結果顯示脈波能量相較於脈波電荷更能用於有效預測電刺激所能產生之肌力(p<0.001)，而綜合周邊與中樞效應的評估結果則顯示不論是以何種方式調變所產生之爆叢皆必須要在中樞神經系統的有效貢獻之下才可能產生額外的強直收縮力量(p<0.001)，此隱含著脊神經元(spinal motoneuron)可經由傳入神經通道(afferent pathway)被電刺激激發的可能性。因此，在排除電刺激脈波調變所可能產生之任何中樞效應的影響時，脈波能量將是一個極具參考價值的電刺激參數，而我們認為這些發現可在缺乏有效之力量回饋機制時(如現實情況不允許使用壓力計或拉力計等)，可被應用於新式神經輔具系統的設計當中以獲得穩定且可信賴之力量輸出。然而，在需求更為嚴謹，即中樞效應的影響存在且極為明顯時，其他相關的電刺激參數(如脈波頻率與強度等)則必須進行更周詳的監控與安排以獲得最有效之電刺激臨床應用。

關鍵字

神經肌肉電刺激 ； 中樞與周邊神經系統之作用 ； 脈波能量 ； 電流/電壓強度調變 ； 脈波頻率調變

並列摘要

A key objective of neuromuscular electrical stimulation (NMES) is to initiate the force normally induced by voluntary contractions in an attempt to improve muscle strength or to delay muscle atrophy. Since voluntary contractions are generally induced by both peripheral and central mechanisms, various approaches are presented herein to evaluate their contributions to forces induced by NMES. Twitch force magnitudes (peripheral contributions) of anesthetized New Zealand White rabbits elicited by single stimulation pulses were first aligned with respect to the electric charge and electrical energy of each individual pulse to determine which electrical parameter provided better consistency during the peripheral evaluation. Stimulation trains were then applied with frequency- or intensity-modulated bursts to induce tetanic forces (central and peripheral contributions) before and after nerve blocks (to block central contributions). The results of the peripheral evaluation indicate that twitch forces evaluated with electrical energy was significantly (p<0.001) better than that evaluated with electric charges, suggesting that electrically stimulated peripheral forces can be reliably predicted by monitoring the energy parameter of stimulation pulses. On the other hand, the results of the overall evaluation (central and peripheral contributions) indicate that temporary bursts evoked significantly greater additional tetanic forces (p<0.001), suggesting the presence of plateau-like behavior in spinal motoneurons triggered via afferent pathways. It is therefore concluded that the electrical energy of a stimulation pulse may be used as a reliable benchmark to associate mechanical (force) and electrical (stimulation pulse) characteristics if the central effects induced by frequency- and intensity-modulated stimulations were disregarded. We believe that these findings can be applied to novel neuroprostheses designs that require better consistency in force output during long term use, thus providing a feasible solution for optimizing such applications of electrical stimulation when real-time force-tracking approaches (e.g., with strain gauges) are unavailable. Nonetheless, careful manipulation of all coinfluencing parameters (i.e., the intensity and frequency of the stimulation pulses) is still necessary to achieve the ultimate goal of generating precise and effective NMES applications.

並列關鍵字

neuromuscular electrical stimulation ； central and peripheral contributions ； pulse energy ； intensity modulation ； frequency modulation

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