Influence of Therapeutic Approach in the Tens-induced Hypoalgesia

The objective of this study was to determine how the therapist’s approachabout intervention may influence TENS-induced hypoalgesia. One hundred and sixty-one healthy subjects agreed to take part in this study and had their demographics, perceived pain intensity, pressure pain threshold (PPT), anxiety level and the state of anxiety inventory (STAI-S) score measured. Subsequently, subjects were placed at random into six study groups, three active and three placebo TENS associated with positive, negative or neutral approaches about electrical stimulation, as given by the investigator. After the treatment, all parameters were reassessed. Active TENS-treated subjects receiving either positive or neutral expectations about intervention showed a significant increase in pressure pain threshold (PPT) (P<0.02) compared to pre-treatment; however, this was not seen in the active TENS group when associated with negative expectations. The intensity of perceived pain was significantly decreased (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.

In this study, particularly, the negative expectations induced previously to the proposed intervention promoted unfavorable outcomes with regards to the analgesic properties of TENS, indicating that the approach taken by the physical therapist should be used to convey positive expectations and avoid those negatives, so as to encourage a more effective treatment.