OBJECTIVE: To evaluate the neurobiological effect of constant, subthreshold magnetic field exposure on symptomatic median nerve compression symptoms, neurophysiology and assess the role of placebo. BACKGROUND: Conservative treatment of moderate and severe CTS has been variable and often results in surgical decompression at the wrist. Design/methods: Eight moderately symptomatic and intractable CTS hands constantly wore identical Elastomag wrist support wraps (unmagnetized versus magnetized 350 gauss) for one month intervals. Identical wraps were then switched at the second month. Baseline assessments included the neurological exam, VAS scores for burning, numbness and tingling twice a day on a 10 point ordinal scale. CMAP/SNAP was determined at baseline and monthly intervals. Clinical follow-up at end of fourth and eighth weeks was compared to baseline. RESULTS: The mean pain scores improved in four patients (57%) which also correlated with clinical benefit. Improvement in Tinel and Phalen sign as well as sensory changes was similarly noted. Placebo effect was detected in one patient (13%). Electrophysiological improvement in distal latencies in 5/8 hands using magnetic treatment was noted compared to no change or worsening in all placebo cases. CONCLUSIONS: Percutaneous magnetic stimulation induced palliative pain relief, presumably via modulation of the unmyelinated C-fibers. Prior studies have suggested an influence on K+ inward rectification excitability. These observations suggest that wearing magnetized wrist wraps appears to be a novel therapeutic agent. However, the underlying neuropathology tends to be progressive.

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