Pain
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Randomized Controlled Trial Clinical Trial
Is TENS purely a placebo effect? A controlled study on chronic low back pain.
Although high-frequency low-intensity transcutaneous electric nerve stimulation (TENS) has been extensively used to relieve low back pain, experimental studies of its effectiveness have yielded contradictory findings mainly due to methodological problems in pain evaluation and placebo control. In the present study, separate visual analog scales (VAS) were used to measure the sensory-discriminative and motivational-affective components of low back pain. Forty-two subjects were randomly assigned to 1 of 3 groups: TENS, placebo-TENS, and no treatment (control). ⋯ This additive effect was not found for placebo-TENS. When evaluated at home, pain intensity was significantly reduced more by TENS than placebo-TENS 1 week after the end of treatment, but not 3 months and 6 months later. At home evaluation of pain unpleasantness in the TENS group was never different from the placebo-TENS group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Recently, it has been reported that loosely constrictive chromic gut ligatures around the sciatic nerve produce behavioral evidence of neuropathic pain in rats. It has been shown that axonal swelling after ligation results in a constriction injury associated with a decrease in the number of both large-diameter myelinated and small-diameter unmyelinated axons, but the mechanism(s) producing spontaneous pain and thermal hyperalgesia remain largely unknown. The present study systematically evaluated potential mechanisms involved in development of the behavioral changes produced by chromic gut ligatures loosely tied around the sciatic nerve. ⋯ These postural changes were most pronounced in the 2-0 and 3-0 chromic gut-treated rats. Chromic gut sutures (4-0, 3-0, or 2-0) tied loosely around the left sciatic nerve also produced a 'dose-dependent' decrease in thermal withdrawal latency that was maximal on postoperative day 3 (25%, 39%, and 41%, respectively). The magnitude of the thermal hyperalgesia declined over time such that a return to baseline was observed by postoperative day 20 in 4-0 and 3-0 chromic gut-treated rats.(ABSTRACT TRUNCATED AT 400 WORDS)