Adjusting Pulse Amplitude During Transcutaneous Electrical Nerve Stimulation Does Not Provide Greater Hypoalgesia

Objectives: Transcutaneous electrical nerve stimulation (TENS) is an electrotherapeutic modality commonly used in rehabilitation to relieve pain. Adjusting pulse amplitude (intensity) during TENS treatment has been suggested to overcome nerve habituation. However, it is still unclear if this procedure leads to greater hypoalgesia. The aim of this study was to determine if the hypoalgesic effect of TENS is greater when pulse amplitude is adjusted throughout the TENS treatment session in chronic low-back pain patients. Design: Randomized double-blind crossover study. Setting: Recruitment and assessment were conducted at the Clinique universitaire de réadaptation de l'Estrie (CURE) of the Faculty of Medicine and Health Sciences of the Université de Sherbrooke . Participants: Twenty-one volunteers with chronic low-back pain were enrolled and completed this investigation. Interventions: Each patient received two high-frequency TENS treatments on two separate sessions: (1) with adjustment of pulse amplitude and (2) without pulse amplitude adjustment. Main outcome measures: Pain intensity and unpleasantness were assessed before, during, and after TENS application with a 10 cm visual analog scale. Results: Both TENS conditions (with and without adjustment of intensity) decreased pain intensity and unpleasantness when compared with baseline. No difference was observed between the two stimulation conditions for both pain intensity and unpleasantness. Conclusion: The current results suggest that adjustment of pulse amplitude during TENS application does not provide greater hypoalgesia in individuals with chronic low-back pain. Future studies are needed to confirm these findings in other pain populations.