Evaluation of neuromuscular transmission by using monopolar needle electrode

Abstract

Objective: To evaluate the value of single-fibre electromyography (SFEMG) with monopolar electrode (MNPE) in revealing neuromuscular transmission dysfunction. Material and methods: We examined the extensor digitorum communis muscle by using single-fibre electrode (SFE) and MNPE sequentially, in randomly assigned 20 healthy volunteers and in 17 patients with known myasthenia gravis (MG). The high-pass filter setting was 3 kHz for MNPE. Ten individual jitter values were calculated for each electrode in every muscle. Repetitive nerve stimulation (RNS) test on trapezius muscle was performed on 15 patients. Results: In controls, the mean jitter values were 27 +/- 9 (10-59) mu s with SFE, and 21 +/- 7.2 (9-56) mu s with MNPE (P = 0.001). In the MG group, the mean jitter values were 52.4 +/- 38 (12-221) mu s with SFE, and 51.8 +/- 34.7 (12-179) mu s with MNPE. Both electrodes identified junction dysfunction in 14 patients. RNS revealed decrement in four patients but 11. Conclusion: SFEMG with SFE is still the gold standard; however, SFEMG with MNPE is superior to RNS like SFEMG with SFE.