Does transcutaneous electrical nerve stimulation (TENS) have a clinically relevant analgesic effect on different pain conditions? A literature review

Transcutaneous electric nerve stimulation (TENS) is a standard therapy used in different painful conditions such as low back pain, diabetic polyneuropathy or arthrosis. However, literature reviews focusing on the effects and the clinical implication of this method in various painful conditions are yet scarce. The purpose of this literature research was to determine, whether TENS provides an analgesic effect on common painful conditions in clinical practice. Literature research was performed using three data bases (Pubmed, Embase, Cochrane Database), focusing on papers published in the space of time from 2007 to 2012. Papers were evaluated from two reviewers independently concerning the clinical outcome, taking account for the level of external evidence according to the German Cochrane levels of evidence (Ia -IV). 133 papers of varying methodological quality dealing with different painful conditions were selected in total. A clinically relevant analgesic effect was described in 90 painful conditions (67%). In 30 painful states (22%), the outcome was inconclusive due to the study design. No significant analgesic effect of TENS was observed in 15 painful conditions (11%). The vast majority of the papers were classified as Cochrane evidence level Ib (n = 64; 48%), followed by level Ia (n = 23; 17%), level III (n = 18; 14%), level IV (n = 15; 11%), level IIb (n = 10; 8%) and level IIa (n = 3; 2%). Most of the studies revealed an analgesic effect in various painful conditions, confirming the usefulness of TENS in clinical practice.