神經組織是一高度分化器官組織, 特別是當中樞神經系統損傷時,復原及再生能力極為有限, 損傷的復原幾乎是不可逆。再者隨分子生物及再生醫學的進步, 許多治療方式藥物都在發展中。利用神經電生理學偵測方式, 評估這些治療方式和藥效, 和如何在手術中避免傷及神經, 這是目前重要的神經電生理學課題。神經電生理學中的體感覺誘發電位(SSEP)和運動誘發電位(MEP),是最常使用於手術中避免傷及神經的偵測工具,特別是避免中樞神經損傷。 但瀕臨中樞神經損傷(central nervous system at risk)的體感覺誘發電位和運動誘發電位變化參數並未完全被建立。體感覺誘發電位使用在動物實驗, 已較廣泛被探討, 參考文獻也較多。目前常用誘發電位型態(morphology), 振幅(amplitude) 或潛時(latency)變化當作參數來比較, 但穩定的參數未完善的被建立。在頭蓋骨電極運動誘發電位(transcranial MEP; cMEP)研究上相對缺乏,所以更無穩定的參數的建立。 在臨床上脊髓損傷, 運動神經組織遠比感覺神經組織更易損傷, 運動誘發電位檢驗似乎比體感覺誘發電位檢驗更加實際且重要。本實驗使用Sprague-Dawley 雌鼠,220-250 克重。 最重要是利
用不鏽鋼螺絲, 在特定位置, 鎖入雌鼠頭蓋骨。 同時使用骨水泥加
強固定螺絲, 如此固定頭蓋骨電極位置。在體感覺誘發電位(SSEP)
實驗, 頭蓋骨電極和胸腰脊椎間韌帶為記錄誘發電位電極; 而在運
動誘發電位(cMEP)實驗, 頭蓋骨電極為電刺激電極。結論得到在體感覺誘發電位(SSEP)實驗: N1 振幅(amplitude)或潛時(latency)相當穩定 ;在運動誘發電位(cMEP)三組肌肉:股四頭肌, 腓腸肌, 蹠肌誘發肌肉電位的實驗, 潛時(latency)最為穩定。不因實驗日期或雌鼠個體不同而有統計差異。在這新設計的穩定動物模式, 可解決可之前運動誘發電位(cMEP)研究的不確定性, 並且確定了參數-潛時(latency)比振幅(amplitude)和電位型態(morphology)的變化更有價值。

Background: The capacity to monitor motor function continuously in an experimental spinal cord injury is highly valuable, but the ability of currently used methods to give reliable information about serial longitudinal long-term follow-up remains poorly established. Transcranial MEP(cMEP) elicited by transcranial
stimulation has been reported to offer a noninvasive method of measuring the functional integrity of the motor neural axis motor cortex to the end-organ muscle.
However, an animal model to study the reliability and consistence in a serial long-term recording of cMEP has yet to be validated.
Study Design: This study was undertaken to evaluate the long-term reliability of cMEP elicited by a new-designed stimulating technique: transcranial cemented-screw
electrical stimulation, Objectives: To validate the acquirability of cMEP from multiple myotomes (Quadriceps, Gastronemius, and plantar muscles of foot) by this new-designed stimulating technique in a rat model; and to clarify its reliability of in a long-term follow-up.
Methods: cMEP were elicited from transcranial electrical stimulation via cementedscrew into inner table over the sensorimotor cortex, and recorded from three muscle
belly (Quadriceps, Gastrocnemius, and plantar muscles of foot) of different myotomes in rat. To specify a standard waveform, characters, and influencing factors, different
stimulating and recording conditions were tested first. To determine the consistency of these cMEPs, the changes of the amplitude and latency was obtained again on days
7, 14, and 21 after the set-up of the screws for stimulating. Finally, we also used radiographies, gross dissection, and histological sections to evaluate the screw-bone interface.
Result: Transcranial electrical stimulation by a cemented-screw technique yield reproducible muscular response in Quadriceps, Gastronemius, and plantar muscles of
foot. The waveforms of these electrical MEPs showed polyphasic signals and the initial peak had variable polarity. With supramaximal stimulation, initial-peak latency was 5.292±0.740, 6.144±1.054 and 9.833±0.737msec; and amplitude was 5.780±1.854,5.898±1.741 and 0.625±0.157 mv in Q, G, and p respectively. Latencies of cMEP in each muscle bellies showed significant difference; as the different distance between stimulating and recording electrodes. However, there were no significant differences
in amplitude among these three muscles. Moreover, the time-course change of latencies of elicited cMEP in the all three muscles showed no significant difference at all time points during the entire 21-day observation. Of the amplitude changes,however, demonstrated a inconsistent variation in all three muscles. These serial measurement and analysis demonstrated latency is the most reliable parameter than amplitude or morphology of the waveform.
Discussion and Conclusion: Conflicting data have been reported on the diagnostic value of cMEP for spinal cord injury, and unlike the extensive studies on SSEP using
various animals, there is surprising little experimental literature on the consistence of cMEP of rat, the most common-used experimental animal in spinal cord injury. These results in study indicate that latency of the cMEP is consistent in all three tested muscles but the amplitude are relative inconsistent. cMEP elicited by this newdesigned stimulating technique is valuable for monitoring spinal cord injury. In experimental settings, a cemented-screw stimulation technique can be used to evoke
cMEP in various muscles in lower-limb consistently, we also recommend observing the changes of latency is more sensitive and specific parameter than morphology and
amplitude.

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