Influence of Therapeutic Approach in the TENS-induced Hypoalgesia

INTRODUCTION: The present study aimed to determine how the therapist's approach about intervention may influence transcutaneous electrical nerve stimulation (TENS)-induced hypoalgesia. METHODS: One hundred and sixty-one pain-free individuals agreed to participate in this study and had their demographics, perceived pain intensity, pressure pain threshold, anxiety level, and the state of anxiety inventory score measured. Subsequently, participants were randomly assigned into 6 study groups, 3 active and 3 placebo TENS associated with positive, negative, or neutral approaches about electrical stimulation, as given by the investigator. After the treatment, all parameters were reassessed. RESULTS: Active TENS-treated participants receiving either positive or neutral expectations about intervention showed a significant increase in pressure pain threshold (P<0.02) compared with pretreatment; however, this was not observed in the active TENS group when associated with negative expectations. The intensity of perceived pain was significantly reduced (P<0.02) only in the active TENS groups in association with either positive or neutral expectations. There was no significant difference in any of the variables assessed in the groups receiving placebo TENS intervention. DISCUSSION: The negative expectations induced prior to the proposed intervention promoted unfavorable outcomes with respect to the analgesic properties of TENS, suggesting that the approach taken by the physical therapist should be used to convey positive expectations and avoid those negatives, to promote more efficacious treatment.