Comparison of stochastic vs. conventional transcutaneous electrical stimulation for pain modulation in patients with electromyographically documented radiculopathy.

OBJECTIVE

To determine if a transcutaneous electrical stimulation (TENS) unit modified to deliver electrical impulses at random (R) or stochastic frequency, called TENS-R, provided better pain relief than conventional TENS.

DESIGN

A prospective, randomized, double-blinded, placebo-controlled study at an urban teaching hospital. A total of 13 adult subjects with radiculopathy on electromyogram and chronic radicular pain rated pain before and after walking 100 feet with proximal (axial) placement of TENS leads with randomized settings on conventional TENS, placebo, or TENS-R and, subsequently, with distal (limb) placement of TENS leads with randomized settings, all on the same day. The pain measures used were the McGill Pain Questionnaire, parts 1 and 2, and the Visual Analog Scale. The functional measure was speed of walking.

RESULTS

Four men and seven women completed the study pain scores, measured by McGill Pain Questionnaire part 2, significantly improved when the patient used TENS-R vs. conventional TENS (P = 0.006, analysis of variance). Placement of TENS electrodes on the back significantly decreased pain compared with lead placement on the legs for McGill Pain Questionnaire part 1 (P = 0.007), McGill Pain Questionnaire part 2 (P = 0.042), and the Visual Analog Scale (P = 0.026) measures.

CONCLUSIONS

Qualitative pain scores significantly improved when the patient used TENS-R vs. conventional TENS. Lead placement of any TENS modality over the back vs. over the leg improved all pain scores.