Podnar Simon
Division of Neurology, Institute of Clinical Neurophysiology, University Medical Center Ljubljana, 1525 Ljubljana, Slovenia.
Neurophysiol Clin. 2004 Oct;34(3-4):153-7. doi: 10.1016/j.neucli.2004.07.002.
In patients with cauda equina or conus medullaris lesions, bilateral electromyographic (EMG) examination of the subcutaneous external anal sphincter (EAS) muscles has been suggested. In spite of its circular shape, EAS should be considered as two separate semicircular muscles. The aim of the present study was to test the hypothesis that information obtained by bilateral examination of the EAS muscle outweighs inconvenience due to additional needle insertions.
A group of 67 patients with clinical and radiological data supportive of cauda equina or conus medullaris lesion was studied. From the subcutaneous EAS muscles motor unit potentials (MUPs) were sampled by the standard concentric EMG needle electrode, and an advanced EMG system with template operated multi-MUP analysis. Severity of EMG abnormalities was determined, and compared in 48 pairs of the left/right subcutaneous EAS muscles.
In 18 patients, bilateral EMG abnormalities were found, in five of them asymmetry of involvement was demonstrated. Unilateral MUP abnormalities were found in 22 patients. The sensitivity of unilateral EMG analysis was 57% and of bilateral examination, 83%.
In patients with suspected cauda equina lesions, as a rule, bilateral EMG of the subcutaneous EAS muscle is recommended.
对于马尾或圆锥病变患者，建议对皮下肛门外括约肌（EAS）进行双侧肌电图（EMG）检查。尽管EAS呈圆形，但应将其视为两块独立的半圆形肌肉。本研究的目的是检验以下假设：对EAS肌肉进行双侧检查所获得的信息超过了因额外针刺带来的不便。
对一组67例具有支持马尾或圆锥病变的临床和放射学资料的患者进行研究。通过标准同心针电极从皮下EAS肌肉采集运动单位电位（MUPs），并使用具有模板操作多MUP分析功能的先进EMG系统。确定EMG异常的严重程度，并在48对左右皮下EAS肌肉中进行比较。
18例患者发现双侧EMG异常，其中5例显示受累不对称。22例患者发现单侧MUP异常。单侧EMG分析的敏感性为57%，双侧检查的敏感性为83%。
对于疑似马尾病变的患者，通常建议对皮下EAS肌肉进行双侧EMG检查。
