The Effects of TENS, Heat, and Cold on the Pain Thresholds Induced by Mechanical Pressure in Healthy Volunteers.

This study was aimed to test whether the administration of transcutaneous electrical neural stimulation (TENS), heat or cold alone, or the coadministration of TENS in combination with heat or with cold may alter the thresholds of the sensory (algosity) and the affective (unpleasantness) dimensions of experimental pain. Mechanical pain induced by a pressure algometer was applied to the tibial shaft of 180 healthy volunteers before and after random application of one of the six following modalities: sham-stimulation, cold, heat, TENS, combination of TENS + cold, or combination of TENS + heat. All modalities were applied in the same (L4) dermatome with the use of Thermotens (Mediseb Technologies Ltd., Hertzelia, Israel), a device which produces quantifiable combinations of thermal and electrical modalities separately or simultaneously. Only the combination of TENS + heat significantly elevated the thresholds of algosity (from 221 mmHg to 262 mmHg, p < 0.01) and of unpleasantness (from 134 ± 9 to 197 ± 9 mmHg; p < 0.001). These findings suggest that the coadministration of several physical modalities can be more efficacious in the treatment of pain than each modality alone.