肌萎缩侧索硬化症患者分裂腿现象分析
Split leg phenomenon in amyotrophic lateral sclerosis

摘要：目的 分析肌萎缩侧索硬化症(ALS)患者的腓总神经和胫神经复合肌肉动作电位波幅(CMAP)的特点，并阐明分裂腿现象及其临床价值。方法 通过对比88例下肢受累ALS患者、100例正常人及24例腰椎病患者的腓总神经和胫神经CMAP特点，分析腓总神经与胫神经CMAP之比，即分裂腿比(SLI)在3组间的差异，并通过ROC曲线分析SLI对于鉴别ALS和腰椎病患者的特异性和敏感性。结果 ①胫神经CMAP在ALS患者中显著高于腰椎病患者[(7.06±3.86)mV vs. (3.31±1.72)mV，P<0.001]，腓总神经CMAP在ALS患者和腰椎病患者两组间无统计学差异[(2.49±1.35)mV vs. (2.41±1.57)mV, P=0.925]，ALS患者中胫前肌失神经电位半定量显著于高于腓肠肌(χ2=61.70，P<0.001)；②SLI在ALS、正常对照和腰椎病患者3组间有统计学差异(H=4.571，P=0.001)，ALS患者SLI显著低于正常对照和腰椎病患者(P<0.001)，正常对照和腰椎病患者两组间SLI无统计学差异(P=0.023)；③SLI与病程、ALSFRS-r评分及疾病进展率均无明显相关性(Rs=-0.008，P=0.94；Rs=0.073，P=0.498；Rs=-0.082，P=0.519)；④ROC曲线显示SLI可用于鉴别ALS和腰椎病患者，最佳截断值为0.634，敏感性=63.4%(95% CI=44.68%～84.37%)，特异性=75%(95% CI=61.03%～77.69%)，阳性预测值=88.1%。结论 分裂腿现象是下肢受累的ALS患者早期即可出现的特异性神经电生理特征，有助于ALS的早期诊断和鉴别诊断，可作为ALS早期诊断的电生理学标志物。
ABSTRACT: Objective? ?To analyze CMAP amplitude of tibial nerve and peroneal nerve in ALS, and elucidate the split leg phenomenon and clinical value. Methods?? Compound muscle action potentials recorded from extensor digitorum brevis and abductor muscle were analyzed in 88 lower-leg involved ALS patients, 100 normal controls and 24 lumbar spondylopathy patients. Results? ?① The CMAP amplitude of tibial nerve were higher in ALS than that in spondylopathy patients [(7.06±3.86)mV vs. (3.31±1.72)mV, P<0.001], and the denervation potentials were greater in tibialisanterior muscle than gastrocnemius muscle (χ2=61.70, P<0.001); ② SLI was inferior in lower leg involved ALS patients compared with normal controls and lumbar spondylopathy patients (P<0.001), but SLI had no difference between normal controls and lumbar spondylopathy patients(P=0.023); ③ SLI was not releted to disease duration, ALSFRS-r score and progression rate (P>0.05); ④ The best cutoff value of SLI was 0.634, sensitivity=63.4% (95% CI=44.68%-84.37%), specificity=75% (95% CI=61.03%-77.69%), the positive predictive value=88.2%. Conclusion? ?The split leg phenomenon is a specific neuroelectrophysiological feature that appears in the early stage of disease in lower limb-involved ALS patients, which can be used as an electrophysiological marker for early diagnosis of ALS