Effect of different forms of transcutaneous electrical nerve stimulation on experimental pain

The purpose of this study was to compare the effects of five different types of transcutaneous electrical nerve stimulation on experimentally induced pain threshold and tolerance in healthy subjects. Fourteen subjects received the following treatments on different days: low frequency TENS, burst frequency TENS, hyperstimulation TENS, high frequency TENS with a low voltage galvanic stimulator, and high frequency TENS with a high voltage galvanic stimulator to the left upper extremity. Pain threshold and tolerance were tested with electric current on a fingertip of the left upper extremity before each treatment, immediately after each treatment, and 20 minutes after the end of each treatment. Data were analyzed using separate two-by-five analyses of variance with repeated measures for pain threshold and tolerance. No significant effects of treatment or time for pain threshold or tolerance were found. A significant interaction between treatment and time for pain threshold was found. Further study is needed to compare the effects of these treatments in patients with clinical pain.