运动单位数目估计在肌萎缩侧索硬化患者随访中的作用

目的 比较多点刺激法和递增法运动单位数目估计在肌萎缩侧索硬化(ALS)患者随访中的作用及差异.方法 120例ALS患者在诊断时,随访3、6、9、12个月时分别进行多点刺激法或递增法运动单位数目估计.多点刺激法:刺激电极分别于腕、腕上6 cm、肘、肘上6 cm,4点刺激正中神经,以超强刺激诱发最大波幅M波;然后从0刺激开始逐渐增加刺激强度直到出现可辨认的单个运动单位电位,逐渐增大刺激强度,记录3个递增的M波.递增法:刺激电极于腕点刺激正中神经,以超强刺激诱发最大M波值,之后自阈强度刺激开始,逐渐增加刺激强度,收集10个递增的M波.比较两种方法在患者随访中所得运动单位数目估计数值的变化及差异.结果 在ALS患者诊断时,随访3、9、12个月时,两种方法所测运动单位数目无差异,均表现为进行性下降;在随访6个月时,多点刺激法所得数值高于递增法(88±6和47±5;t=1.72,P=0.04).结论 多点刺激法和递增法运动单位数目估计可用于ALS患者的随访研究,在疾病不同时期,两种方法所得数值可以不同.

Comparison of multiple point stimulation and incremental stimulation motor unit number estimation in follow-up study of patients with amyotrophic lateral sclerosis

Objective To compare two common techniques for motor unit number estimation (MUNE), multiple point stimulation(MPS) and incremental stimulation, and determine which is preferable in the follow-up study of patients with amyotrophic lateral sclerosis (ALS).Methods MPS or incremental stimulation MUNE was recorded respectively in 120 ALS patients at baseline and month 3, 6, 9 ,and 12 after study entry.The maximal baseline to negative peak compound muscle action potential (CMAP) amplitude was recorded.For multiple point stimulation, the stimuli sites included the skin of the wrist, 6 cm above the wrist, elbow and 6 cm above the elbow.Individual motor unit responses were obtained by moving thestimulating electrode and isolating threshold responses.Then, with finely graded stimulus intensity at one point, 3 steps in a CMAP were investigated.For incremental stimulation, stimulus intensity was slowlyincreased from subthreshold levels until a small, all-or-none response was evoked.The intensity was slowly increased until the response increased in a quantal fashion.This process was repeated for a total of 10 increments.Single motor unit potential were obtained by subtracting amplitudes of each response from that of the prior response.The values obtained from two methods were compared.Results The value of MUNE declined in the follow-up period.MUNE obtained from MPS was the same as that gained from incremental stimulation at the baseline and the 3rd, 9th, 12th month after study entry, while MUNE obtained in MPS was more than that obtained from incremental stimulation at the 6th month after study entry ( 88 ± 6 and 47 ± 5;t = 1.72, P = 0.04).Conclusions Both MPS and incremental stimulation are certain in the follow-up study of patients with amyotrophic lateral sclerosis.The value of MUNE obtained from two methods might be different in some period.