[Electroanalgesia by transcutaneous stimulation (TNS). Response to the naloxone test]

The authors, after a review of the literature about TNS, suggest the comparison between three different TNS techniques from two points of view: A) Pain relief estimate; B) Response to Naloxone Test. To this purpose a impulse generator delivered a biphasic square-wave stimulus with duration of 0.40 msec and amplitude (peak to peak) to 130 mVolt, was used. TNS techniques used are so characterized 1) Frequency 80 Hz; Duration 30'; 2) Frequency 80 Hz; Duration over 120'; 3) Frequency 2/4 Hz; Duration over 120'. Although the techniques used for Group (1) provided the best numerical result in the evaluation of the pain relief, endorphine activity cannot be maintained owing to Naloxone Test negativity. Pain relief of (2) and (3) Group was statistically significant although not numerically at the same level of (1) Group. In the laters, on the contrary, positivity of Naloxone Test seems to hint at the activation of endorphine. This fact suggest to the authors hypothesis in the purpose to spot TNS site of action.