Relation of electromyography-induced pain to type of recording electrodes

Pain is an important consideration in the performance of needle electromyography (EMG). Prior investigations have suggested that pain is greater with a concentric needle electrode (CNE) than monopolar needle electrode (MNE). This prospective randomized study tested this hypothesis using improved methodology and disposable rather than reusable needle electrodes. Ninety consecutive outpatients were enrolled and randomized to CNE (diameter = 0.46 mm) or MNE (diameter = 0.41 mm) arms. Subjects underwent a standardized 4 limb-muscle needle EMG protocol during which pretest and posttest verbal analog pain scale (0-10) measures were obtained. As anticipated, EMG-induced pain was significantly higher (P < 0.001) than pre-EMG baseline pain. However, analysis of variance (ANOVA) revealed no significant differences in pain ratings between the CNE and MNE arms. Among other factors analyzed, only gender significantly influenced EMG-induced pain, with females reporting higher levels than males. Thus, pain is not an important selection criterion for type of disposable needle electrode.