不同模式超音波的刺激對坐骨神經訊號傳遞之影響

Effects of ultrasonic stimulations by different modes on the signal conduction of the sciatic nerve

顏雅聆(Ya-Ling Yen)

指導教授 ： 王士豪

中原大學/工學院/醫學工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500004

摘要

文獻顯示超音波不僅對神經組織之興奮性具有可逆性之促進效果，且逐漸發現低能量超音波將促進損傷神經之修復，但卻無法分辨熱效應與非熱效應分別對神經組織之實質影響，因此本研究旨在探討不同模式超音波的刺激對坐骨神經訊號傳遞之影響。

實驗共分為溫度實驗與超音波實驗，採用頻率5 MHz，平均能量為500 mW之不同工作週期超音波刺激神經組織，結果以複合動作電位振幅、神經傳導速率與中心頻率之變化百分比分析溫度或超音波對神經組織訊號傳遞的影響。並量測實驗過程中神經刺激槽內石蠟油溫度變化情形，最終結果以每單位溫度之訊號參數變化量作為不同模式低能量超音波是否利用非熱效應影響神經傳導訊號之依據。

由實驗結果可發現超音波對神經組織興奮性的調變具有可逆性，超音波可提高神經組織之興奮性，而當超音波停止刺激，複合動作電位振幅即隨之衰減，呈現動態之可逆性促進現象。而溫度對神經組織之影響，僅可輕微增加神經興奮性，但卻大幅度增加神經傳導速率。相同溫度變化下，不同工作週期之超音波刺激神經組織則可使複合動作電位振幅顯著增加，顯示超音波可能藉由非熱效應影響細胞膜上離子通道或開關機制所導致。再者，由超音波實驗亦推測超音波之非熱效應有藉由改變神經纖維物理特性進而促進神經傳導之可能。

關鍵字

神經複合動作電位 ； 神經傳導速率 ； 超音波生物效應

並列摘要

The stimulation of neural tissues by ultrasound can not only enhance the reversible excitability but improve the rehabilitation in peripheral neuropathy shown in pervious studies. The mechanism of individual bioeffect on neural tissues was unclear, hence the study aimed to explore effects of ultrasonic stimulations by different modes on the signal conduction of the sciatic nerve.

A 5 MHz transducer was employed to generate 500 mW at different duty cycles ranged from 25 to 100 %, and 2 KHz pulse repetition frequency, of ultrasounds administrated to in vitro sciatic nerves. The conduction properties of an excised nerve were assessed by the magnitude of compound action potential (CAP), the nerve conduction velocity (NCV) and the central frequency analyzed from neural signals before and after ultrasound stimulations. Further, results collected from thermal modification and ultrasound irradiation were compared with each other to determine how ultrasound non-thermal mechanism alone influences the neural signal conduction.

Results showed that low-intensity ultrasound could efficiently enhance the reversible neural excitability. In this way, the magnitude of CAP rapidly increased or decreased with sonication or termination. On the other hand, thermal agent induced the neural excitability slightly, but largely augmented the NCV. Accordingly, the membrane permeability induced by the non-thermal effect was suggested to enhance the CAP, and the NCV augmentation might result form both bioeffects.

並列關鍵字

Ultrasound bioeffect ； Compound action potential ； Nerve conduction velocity

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