經皮脈衝射頻電刺激於病理性神經疼痛之止痛效果研究

Abstract

疼痛是身體伴隨著疾病而發出的警告訊號，其中壓迫性神經疼痛在生活中是常見的症狀，像是椎間盤突出、腕隧道症候群、脊椎疾病…等，隨著症狀的嚴重性而導致神經產生六個月以上的慢性疼痛，也被定義為病理性神經疼痛；臨床上使用高電壓單極脈衝射頻電刺激於背根神經節能達到長效止痛的效果，透過電場而非熱破壞，以侵入方式在背根神經節電刺激能夠減緩病理性神經疼痛。然而，脈衝射頻電刺激抑制疼痛機轉雖仍未清楚，但已用於臨床治療多年，其中電場強度可能為脈衝射頻電刺激的止痛依據。 早期研究中使用植入雙極低振幅脈衝射頻電刺激在大白鼠背根神經節證明有抑制病理性神經疼痛之效果，本研究設計一低振幅攜帶式經皮脈衝射頻電刺激器針對病理性神經疼痛由大白鼠至臨床試驗進行評估，透過經皮方式於腕部正中神經壓迫疼痛止痛效果，以大白鼠正中神經建立一均勻壓迫神經模型，使用老鼠足底疼痛量測系統評估，透過經皮方式進行不同振幅(±5V, ±10V, ±22.5V)的電刺激觀察疼痛變化；實驗發現，壓迫性疼痛模型能有效地使足底耐受力降低，在施加單次脈衝射頻電刺激後耐受力能夠增加至正常老鼠的80%。隨著振幅強度變增加，其疼痛緩解的時間上也有正向的表現，透過經皮方式於淺層疼痛神經使用單次低振幅(±5V)參數可以達到止痛效果但時間能維持三周並降至40%，而高振幅(±22.5V)在單次電刺激九週後仍能維持於60%的耐受程度，於十二週後下降至40%以下；臨床試驗針對腕隧道症候群之病人進行經皮電刺激，發現透過±5V並無顯著止痛效果，而±10V可重複減緩病患疼痛7-14天，透過此研究結果得知，以經皮脈衝射頻在腕隧道症候群可獲得更好的止痛結果

Kinds of pains usually happen with diseases as symptoms, of which Compression nerve pain is a common one, for example, pains caused by disc herniation, carpal tunnel syndrome, and spinal diseases. When those pains last longer than 6 months, they are defined as Neuropathic Pain. For those patients suffering from these chronic pains, improving their life quality by reducing the pains effectively would be the most helpful treatment. High-voltage unipolar pulsed radiofrequency stimulation on dorsal root ganglion, as an invasive method, via electric field effect rather than thermal damage, has been practiced for years on Neuropathic Pain treatment. The occurrence of pain can be decreased, and a long-term analgesia can be realized by applying stimulation, however, the principles of this method still remains unknown. In clinical observation, the effect of stimulation is related to the electric field parameters, and larger current is needed when curing pains in deeper tissue. In this study, a portable transcutaneous low-voltage pulsed radiofrequency stimulation device for neuropathic pain treatment is proposed from rat to clinical trial, according to the therapeutic effects of low-voltage bipolar pulsed radiofrequency stimulation on dorsal root ganglion on those diseases reported in previous studies. In this research, a moderate compression nerve model was established on median nerve of rat, then transcutaneous pulsed radiofrequency stimulations with different voltage amplitudes (±5V, ±10V, and ±22.5V) were applied. The feelings of pain of rats before and after stimulation were quantitatively measured and compared. The results show tpaw withdrawn score of rats were effectively reduced by the compression model, and the tolerance to pain can be increased to 80% of naive rat after accepting pulsed radio-frequency stimulation for 1 time. The effect of analgesia varied with amplitude of stimulation: For shallow pain nerve, analgesia lasted for 3 weeks and the tolerance to pain fell to 40% at 4th week after low-voltage. (±5V) 1 time; analgesia lasted for 9 weeks, the tolerance fell to 60% at 10th week, then fell to 40% at 12th week after high-voltage (±22.5V) 1 time. In clinical trial, ±5V were not show significant analgesic effect, ±10V can be repeated reduction pain until 7-14 days . Through the results, pulsed radiofreqeuency can be implemented on transcutaneous to gain better for pain relief.