週邊神經常因壓迫、牽拉或外傷性撕裂而受傷，影響感覺與神經功能，用以評估神經損傷的方法包括分子生物學中許多標記的測量、病理組織切片、動物動作行為模式、以及電生理評估。本研究欲以傳統的電刺激及新興的磁波刺激(magnetic stimulation) 評估大鼠週邊神經損傷並比較其結果。
本研究將大鼠分成三組: 第一組為對照組(n = 8)； 第二組採用坐骨神經綁紮 (n = 8)，對大鼠左側坐骨神經進行綁紮造成神經損傷；第三組利用丙烯醯胺(Acrylamide) (n = 8)，給予腹膜內注射丙烯醯胺(50 mg/kg) 造成神經損傷，每週二次，共四週。電生理評估的時點為術前三天、術後每隔1週共4週，項目包括坐骨神經(至脛前肌、腓腸肌)的運動神經傳導速度與複合神經電位振幅大小、H反射、F波、磁波刺激產生運動誘發電位振幅大小及潛時(latency)、肌電圖訊號(脛前肌、腓腸肌)。
研究結果顯示電刺激與磁波刺激在兩組神經損傷模式中均可見到電位振幅大小明顯下降，磁波刺激所得的電位振幅約為電刺激之76-85%。至於潛時並未在神經損傷模式中明顯延長，因為其波形會受到電導體傳導(volume conduction)干擾，導致判讀數據易產生誤差，磁波刺激所得的潛時約較電刺激延長0.596±0.258 ms。由於大鼠後肢距離短，無法以磁波刺激檢查神經傳導速度、H反射與F波。反之，電刺激評估中呈現神經損傷老鼠之神經傳導速度變慢、H反射與F波潛時延長或消失。此外，肌電圖可明顯偵測到神經損傷老鼠的去神經自發性電位。綜言之，腰薦神經根磁波刺激為非侵入性，使用上有其便利，但需累積更多數據與經驗，才能成為可信賴的評估工具。

Numerous mechanisms contribute to peripheral nerve injuries such as chemical intoxication, compression, stretching and avulsion, which usually result in severe damage to the sensory and motor functions. The current approaches for evaluating nerve regeneration include expression analysis of molecular markers, histological analysis, behavior testing and electrophysiological studies. The aim of this study is to compare the diagnostic efficacy using the recently developed magnetic stimulation approach with that of conventional electrical stimulation method in different models of peripheral neuropathy and to compare in terms of latency and amplitude of the evoked response by electrical and magnetic stimulation.
Adult male Sprague Dawley rats (250-300 g, n = 24) were divided into three groups: (1) control group, (2) sciatic nerve ligation group and (3) acrylamide intoxication group. The electrophysiological studies were carried out 3 days before ligation and every 7 days after ligation for 4 weeks. The measurements included amplitude and onset latency of maximal compound nerve action potential (CMAP) in branches of sciatic nerve (nerves to the gastrocnemius, tibialis anterior), motor nerve conduction velocity, H-reflex, F-wave, amplitude and onset latency of motor evoked potential by lumbosacral motor root magnetic stimulation, and denervation by electromyography (gastrocnemius, tibialis anterior).
The results from studies using magnetic and electrical stimulation showed prominent reduction of CMAP amplitude in rats of sciatic nerve ligation and acrylamide intoxication group. The CMAP amplitude measured by magnetic stimulation was 76~85% of that by electrical stimulation. By either magnetic stimulation or electrical stimulation, there was no significant difference in the mean onset latency of CMAP between control and neuropathy groups. Volume conduction accounts for the interference of waveform and error is inevitable. Because of the short distance of hind limb of the rat, the nerve conduction velocity (NCV), H-reflex and F-wave could not be determined using magnetic stimulation. In contrast, electrophysiological analysis by electrical stimulation revealed slowed NCV, prolonged or absent H-reflex and F-wave in animals of neuropathy groups. Electromyography showed prominent denervation potentials over the sampling muscles in both models.
In conclusion, magnetic stimulation of lumbosacral motor root is non-invasive and convenient. However, further improvement and establishment of basic parameters are required to facilitate a reliable tool in evaluation of peripheral nerve injury.

Abstract (Chinese)--------------------------- 1
Abstract (English) -------------------------- 2
Background----------------------------------- 4
Introduction of Magnetic stimulation--------- 4
Conventional Nerve Conduction Studies ------- 5
Purpose ------------------------------------- 7
Materials and Methods ----------------------- 8
Animals-------------------------------------- 8
Peripheral nerve injury models--------------- 8
Sciatic nerve ligation model----------------- 8
Acrylamide intoxication model---------------- 8
Electrophysiological measurements------------ 9
Electrical stimulation----------------------- 9
Magnetic stimulation------------------------- 9
Statistical analysis-------------------------10
Results ------------------------------------- 11
Morphology of CMAP -------------------------- 11
Comparison of amplitude --------------------- 11
Comparison of onset latency ----------------- 11
Nerve Conduction Velocity-------------------- 11
H-reflex ------------------------------------ 12
F-wave -------------------------------------- 12
Electromyography ---------------------------- 12
Discussion----------------------------------- 13
Morphology of CMAP -------------------------- 13
Comparison of amplitude --------------------- 14
Comparison of onset latency ----------------- 15
Nerve Conduction Velocity-------------------- 15
H-reflex ------------------------------------ 15
F-wave -------------------------------------- 15
Electromyography ---------------------------- 16
Conclusion ---------------------------------- 18
References ---------------------------------- 19
Tables -------------------------------------- 22
Table 1 Mean values of CMAP amplitude ------- 22
Table 2 Mean values of CMAP latency --------- 23
Figures
Figure 1 Different kinds of magnetic stimulators --24
Figure 2 Positioning of stimulators ---------------25
Figure 3 Morphology of CMAP------------------------26
Figure 4 Changes in CMAP amplitude by magnetic stimulation ------------- 27
Figure 5 Changes in CMAP amplitude by electrical stimulation ------------- 28
Figure 6 Comparison of CMAP amplitude ------------29
Figure 7 Changes in CMAP latency by magnetic stimulation ---------------- 30
Figure 8 Changes in CMAP latency by electrical stimulation ---------------- 31
Figure 9 Comparison of CMAP latency ------------- 32
Figure10 Changes in nerve conduction velocity ----33
Figure 11 Normal F-wave and H-reflex in control group -- 34
Figure 12 Changes in latency of H-reflex -------------- 35 Figure 13 Changes in latency of F-wave --------------- 36
Figure 14 Denervation grading in Electromyography ---- 37

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