肌萎缩侧索硬化患者复合肌肉动作电位特点分析及其与临床关系的研究

目的分析肌萎缩侧索硬化患者复合肌肉动作电位之特点,探讨波幅改变与肌力、病程以及神经功能等级评分等方面的关系。方法收集2001年5月-2004年11月肌电图检查表现为广泛神经源性损害的肌萎缩侧索硬化患者127例,根据ElEscorial诊断标准,确诊级43例、拟诊级39例、可能级13例、可疑级32例。选择其中确诊级和拟诊级患者82例进行神经功能评分和Appel肌萎缩侧索硬化量表评分,然后对其复合肌肉动作电位波幅值与肌力、病程以及神经功能评分变化间的关系进行比较分析。结果(1)82例患者复合肌肉动作电位波幅下降,与肌力改变呈明显指数拟合关系(r=0.969,P=0.001)。(2)同一患者波幅水平随病程而逐渐降低,波幅下降速度较慢者病程较长;不同患者的波幅与病程无显著相关(r=!0.077,P=0.502)。(3)复合肌肉动作电位波幅水平降低与神经功能等级评分呈显著正相关(r=0.412,P=0.001),与Appel评分呈显著负相关(r=!0.549,P=0.001)。(4)患者复合肌肉动作电位波幅水平的降低与运动神经传导速度无明显相关(r=!0.087,P=0.545),但若将波幅与传导速度转换为正常下限的百分比取其平方根后,二者间则呈线性相关(r=0.382,P<0.001)。结论复合肌肉动作电位波幅改变是肌萎缩侧索硬化原发性与继发性病理改变共同作用的结果,随着患者肌无力和肌萎缩症状的逐渐加重,复合肌肉动作电位波幅亦明显下降,但由于此时髓鞘仍保留完整,传导速度仍可保持正常,提示肌萎缩侧索硬化患者肌力下降的机制主要系下运动神经元损害所致。在同一患者,复查时显示复合肌肉动作电位波幅随病程进展而逐渐下降,但尚难建立反映二者平行关系的时间-波幅曲线,提示复合肌肉动作电位波幅改变与病程关系较为复杂。此外,复合肌肉动作电位波幅与肌萎缩侧索硬化患者的神经功能等级评分和Appel量表评分明显相关,提示早期波幅下降较慢者病情相对较轻。

The correlation between clinical manifestations and features of compound muscle action potentials in patients with amyotrophic lateral sclerosis

Objective To analyse the amplitude characteristics of the compound muscle action potentials (CMAP) in patients with amyotrophic lateral sclerosis (ALS), and explore the correlation between CMAP amplitude and muscle strength, disease duration and neurological functional score. Methods The 127 patients of EMG presenting generalized neurogenic amyotrophic lateral sclerosis during May 2001-Nov 2004 were collected. These patients were diagnosed as definite cases 43, assume cases 39, probable cases 13 and suspicious cases 32 according to El Escorial diagnosis criterion. Among them a total of 82 cases of definite and assume cases were enrolled for evaluation by the amyotrophic lateral sclerosis function rating scale and Appel's amyotrophic laterosclerosis scale. Then the association of compound muscle action potential (CMAP) with changes of muscls strength, disease duration and neurological functional score was comparatively analyzed. Results Decreasing of CMAP amplitude correlated strongly with weakening of muscle strength, the relation could be fitted by an exponential equation (r = 0.969, P = 0.001); CMAP amplitude declined sharply or slowly over time to the same patient, the slower decline in CMAP amplitude correlated with a longer disease duration. There was no significant difference of muscle action potential amplitude levels among the different patients (r =- 0.077, P = 0.502). There was significant positive correlation of decreasing CMAP amplitude level with neurological functional score (r = 0.412, P = 0.001) but significant negative correlation with Appel's scale (r = - 0.549, P = 0.001). There was no simple linear correlation of decreasing CMAP amplitude with motor nerver conduction velocity (CV) (r =- 0.087, P = 0.545). But it presented linear correlation between the square roots when converting the amplitude and conductive velocity to the percentage of the lower limit of their normal levels and calculated their square root (r = 0.382, P < 0.001). Conclusion The changes of CMAP amplitude is resulted in both primary and secondary pathological changes of ALS. The CAMP significantly decreases when the exacerbation of ALS symptoms; but at that time, the conductive veloeity of motor nerve still keeps normal as the myelin sheath remains intact. Thus the mechanism of muscle strength decreasing in ALS is mainly due to the injury of motor nerve neurons. In the following up of patients, the CMAP amplitude is gradually decline as the disease course prolong in the same patient, but time-amplitude parallel relation curve could not be established yet. It shows the relation between CMAP amplitude change and disease course is rather complicate. The significant correlation of CMAP amplitude and the amyotrophic lateral sclerosis function rating scale of ALS patients or Apple's scale demonstrates that the slower of early decreasing amplitude, the milder the patient's condition.