Differences in pain perception in women using concentric and monopolar needles.

Objective: To examine pain perception using concentric needle electrodes and monopolar needle electrodes in an all-female study group without underlying hand or arm pain complaints, using study subjects as their own controls.

Design: Prospective randomized study. Two muscles--the biceps and abductor pollicis brevis (APB)--were examined using both a concentric needle electrode and a monopolar needle electrode.

Setting: University community.

Participants: Eighty healthy female employees at the University of Utah and Primary Children's Hospital were enrolled. All completed the study.

Interventions: Not applicable.

Main Outcome Measures: Pain scores. Posttest verbal analog pain scale (0-10) measures were obtained after each muscle was studied. A subset of subjects (n=51) was asked to identify needle preference after completion of the study.

Results: There was no significant difference in mean pain scores between the concentric needle electrode and the monopolar needle electrode (3.06 and 3.10, respectively; P=.803). The APB muscle was significantly more painful than the biceps muscle with both needle types (mean pain scores, 3.92 and 2.24, respectively; P<.001). In the subset of subjects asked to identify needle preference after completion of the study, 21 chose a concentric needle electrode and 30 a monopolar needle electrode. This difference was not statistically significant. However, verbal analog pain scores were lower with the needle preferred by each subject (P<.20).

Conclusions: There is no significant difference in mean pain scores reported between a concentric needle electrode and a monopolar needle electrode. Subjects were clear on the needle they preferred, and the pain scores reported for the less painful needle were lower than those for the other needle.