Motor Unit Recruitment and Amplitude of Motor Nerve Evoked Muscle Action Potential for the Assessment ofAxon Loss in Lumbar Radiculopathy

探討以運動單元徵召和運動神經所激發之肌肉動作電位的振幅 : 評估腰椎神經根病變的軸索喪失程度

官大紳(Ta-Shen Kuan) ； 陳炫名(Shiuauun-Ming Chen) ； 吳炎村(Yen-Chun Wu) ； 薛澤杰(Tse-Chieh Hsueh) ； 洪章仁(Chang-Zern Hong)

《中華民國復健醫學會雜誌》 24卷1期 (1996/06) Pp. 1-10

摘要

Retrospective review of electromyographic (EMG) reports on 98 patients with clinical diagnosis of lumbar radiculopathy was performed to assess the correlation between the mean motor unit recruitment (MUR) of L5 and/or S1 innervated muscles and amplitude of compound muscle action potential (A-CMAP) in motor nerve conduction study (MNCS) of peroneal or tibial nerves. MUR was measured as the ratio of motor units to the number of firing motor units in 4 scales (from 0 to 3: 0= no motor unit potential recorded; 1= a ratio greater than 15; 2 = a ratio between 5 and 15; and 3 = a ratio less than 5). A-CMAP was measured from the baseline to the peak of the evoked muscle action potentials recorded from extensor digitorum brevis and abductor hallucis muscles for peroneal and tibial nerve respectively. It was found that
the mean MUR of muscles innervated by L5+S1 roots was significantly lower (p＜0.05) in patients with EMG evidence of L5, S1, or L5+S1 radiculopathy compared to that with normal EMG findings. Mean A-CMAP of tibial nerve (but not of peroneal nerve) was significantly lower (p＜0.05) in patients with EMG evidence of L5, Sl, or L5+S1 radiculopathy compared to that with normal EMG findings. However, based on analysis of linear regression, the correlation between mean MUR and A-CMAP was very low (r＜ 0.5). This correlation was also weak (r ＜ 0.7) even when the patients with normal MURS were excluded. There was a tendency that correlation coefficients for comparison between mean MUR and A-CMAP of tibial nerve were higher than that of peroneal nerve. It is suggested that there is a poor correlation between mean MUR in EMG test and A-CMAP in MNCS in patients with lumbar radiculopathy, although both measurements are useful in the assessment of motor units loss. In patients with lumbar radiculopathy, measuring A-CMAP of tibial nerve may estimate axon loss better than that of peroneal nerve.

並列摘要

Retrospective review of electromyographic (EMG) reports on 98 patients with clinical diagnosis of lumbar radiculopathy was performed to assess the correlation between the mean motor unit recruitment (MUR) of L5 and/or S1 innervated muscles and amplitude of compound muscle action potential (A-CMAP) in motor nerve conduction study (MNCS) of peroneal or tibial nerves. MUR was measured as the ratio of motor units to the number of firing motor units in 4 scales (from 0 to 3: 0= no motor unit potential recorded; 1= a ratio greater than 15; 2 = a ratio between 5 and 15; and 3 = a ratio less than 5). A-CMAP was measured from the baseline to the peak of the evoked muscle action potentials recorded from extensor digitorum brevis and abductor hallucis muscles for peroneal and tibial nerve respectively. It was found that
the mean MUR of muscles innervated by L5+S1 roots was significantly lower (p＜0.05) in patients with EMG evidence of L5, S1, or L5+S1 radiculopathy compared to that with normal EMG findings. Mean A-CMAP of tibial nerve (but not of peroneal nerve) was significantly lower (p＜0.05) in patients with EMG evidence of L5, Sl, or L5+S1 radiculopathy compared to that with normal EMG findings. However, based on analysis of linear regression, the correlation between mean MUR and A-CMAP was very low (r＜ 0.5). This correlation was also weak (r ＜ 0.7) even when the patients with normal MURS were excluded. There was a tendency that correlation coefficients for comparison between mean MUR and A-CMAP of tibial nerve were higher than that of peroneal nerve. It is suggested that there is a poor correlation between mean MUR in EMG test and A-CMAP in MNCS in patients with lumbar radiculopathy, although both measurements are useful in the assessment of motor units loss. In patients with lumbar radiculopathy, measuring A-CMAP of tibial nerve may estimate axon loss better than that of peroneal nerve.

並列關鍵字

electromyography ； nerve conduction ； radiculopathy