OBJECTIVE Motor unit number index (MUNIX) is proposed to monitor neuromuscular disorders. Our objective is to determine the intra-individual variability over time of the MUNIX. METHODS In 11 different hospital centres, MUNIX was assessed twice, at least 3 months apart (range 90-360 days), in tibialis anterior (TA), abductor pollicis brevis (APB), abductor digiti minimi (ADM) and deltoid muscles in 118 healthy subjects. MUNIX sum score 2, 3 and 4 were respectively the sum of the MUNIX of the TA and ADM, of the TA, APB and ADM and of the TA, APB, ADM and deltoid muscles. RESULTS The repeatability of the MUNIX was better for sum scores than for single muscle recordings. The variability of the MUNIX was independent of sex, age, interval between measurements and was lower for experienced than non-experienced operators. The 95th percentile of the coefficient of variability of the MUNIX sum score 2, 3 and 4 were respectively 22%, 18% and 15% for experienced operators. CONCLUSIONS The MUNIX technique must be performed by experienced operators on several muscles to reduce its variability and improve its reliability. SIGNIFICANCE A variation of the MUNIX sum score ≥20% can be interpreted as a significant change of muscle innervation.

中文翻译：

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作为个体生物标志物的运动单位数指数：健康受试者随时间推移的个体内变异性参考限值

目的 运动单位数指数 (MUNIX) 被提议用于监测神经肌肉疾病。我们的目标是确定 MUNIX 随时间变化的个体内变异性。方法 在 11 个不同的医院中心，对 MUNIX 进行了两次评估，至少间隔 3 个月（范围 90-360 天），分别是胫前肌 (TA)、拇短外展肌 (APB)、小指外展肌 (ADM) 和三角肌在 118健康受试者。MUNIX总分2、3和4分别为TA和ADM的MUNIX总和，TA、APB和ADM的MUNIX总和以及TA、APB、ADM和三角肌的MUNIX总和。结果 与单肌肉记录相比，MUNIX 的可重复性在总分方面更好。MUNIX 的可变性与性别、年龄、测量间隔无关，并且对于有经验的操作员来说比没有经验的操作员要低。对于有经验的操作员，MUNIX 总和得分 2、3 和 4 的变异系数的第 95 个百分位数分别为 22%、18% 和 15%。结论 MUNIX 技术必须由经验丰富的操作员在多块肌肉上执行，以减少其可变性并提高其可靠性。意义 MUNIX 总分≥20% 的变化可以解释为肌肉神经支配的显着变化。