Boërio Delphine, Hogrel Jean-Yves, Bassez Guillaume, Lefaucheur Jean-Pascal
Service de Physiologie--Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique--Hôpitaux de Paris, Créteil, France.
Clin Neurophysiol. 2007 Nov;118(11):2375-82. doi: 10.1016/j.clinph.2007.07.018. Epub 2007 Sep 24.
To study neuromuscular excitability in patients with dystrophia myotonica type 1 (DM1).
The neuromuscular recovery cycle following motor nerve stimulation was assessed in 16 DM1 patients who had no sign of peripheral neuropathy or diabetes. Compound muscle action potentials were recorded from the adductor digiti minimi muscle to ulnar nerve stimulation at the wrist. Paired pulses were delivered, consisting of a conditioning stimulus of supramaximal intensity, followed by a submaximal test stimulus. Interstimuli intervals (ISIs) ranged between 1 and 8ms. Durations of the absolute and relative refractory periods (ARP, RRP) and percentages of refractoriness and supernormality at ISIs of 2.6 and 7ms, respectively, were computed using a subtraction method. The results obtained in the series of DM1 patients were compared to those obtained in six patients with other forms of myotonia and to normative values established in a series of age-matched healthy subjects. Correlations were made between excitability parameters, the number of cytosine-thymine-guanine (CTG) repeats, and the severity of myotonia, scored clinically.
Compared to controls, DM1 patients presented prolonged durations of ARP and RRP, increased refractoriness and reduced supernormality. The decrease in refractoriness correlated with both the number of CTG repeats and the severity of myotonia.
Changes in the recovery cycle following supramaximal motor nerve stimulation revealed the existence of subtle alterations of neuromuscular excitability in DM1 patients.
Increase in refractoriness together with a reduced supernormality was consistent with a process of membrane depolarization. Such a depolarization may be related to the loss of chloride channels or to alterations in sodium conductance in the motor axon or the muscle fiber.
研究1型强直性肌营养不良症（DM1）患者的神经肌肉兴奋性。
对16例无周围神经病变或糖尿病迹象的DM1患者进行运动神经刺激后的神经肌肉恢复周期评估。在腕部对尺神经进行刺激，从尺侧小指展肌记录复合肌肉动作电位。给予成对脉冲，包括一个超强强度的条件刺激，随后是一个次最大强度的测试刺激。刺激间隔（ISI）范围为1至8毫秒。分别使用减法方法计算在2.6毫秒和7毫秒的ISI时绝对和相对不应期（ARP、RRP）的持续时间以及不应期和超常期的百分比。将DM1患者系列的结果与6例其他形式肌强直患者的结果以及在一系列年龄匹配的健康受试者中建立的正常值进行比较。对兴奋性参数、胞嘧啶 - 胸腺嘧啶 - 鸟嘌呤（CTG）重复次数和临床评分的肌强直严重程度之间进行相关性分析。
与对照组相比，DM1患者的ARP和RRP持续时间延长，不应期增加，超常期减少。不应期的降低与CTG重复次数和肌强直严重程度均相关。
超强运动神经刺激后恢复周期的变化揭示了DM1患者神经肌肉兴奋性存在细微改变。
不应期增加和超常期减少与膜去极化过程一致。这种去极化可能与氯离子通道的丧失或运动轴突或肌纤维中钠电导的改变有关。
