gms | German Medical Science

Objective: The aim of this study was to investigate the predictive value of percutaneous electrical nerve stimulation (PENS) in peripheral nerve stimulation for chronic neuropathic pain using an electro-acupuncture device (EA).

Method: 12 patients being evaluated for PENS for chronic neuropathic pain were included in this survey. All patients suffered from a regional pain syndrome in a skin area innervated by a single peripheral nerve. Stimulation with acupuncture needles was applied with continuous high (80 Hz) frequency stimulation at 180µs. Position, polarity, frequency and amperage threshold of perception and adverse effects were noted. Additionally paresthesia, burning, pain control and coverage of the pain area were documented. A score (StimScore) was developed by the authors to evaluate effects in a standardized manner. This StimScore comprises coverage of the painful area, therapeutic range and amperage required for succesul stimulation. StimScore was determined during EA, during test stimulation and under final stimulation.

Results: PENS via EA was well tolerated by all patients. 7/12 patients (58%) were classified as successfully treated, 5/12 patients (42%) as unsuccessful with successful treatment defined as at least 50% reduction in pain on the VAS on 3 month control. The mean overall reduction in the first group was 4.0 points (SD = 2.87, p = .010) and 2.4 points (SD = 1.29, p = .014) respectively on the VAS. In the successful stimulation group a mean StimScore of 13.14 (SD 11.19 - 15.0) was calculated vs. 10.4 (95% CI 8.52 - 12.28) in the unsuccessful stimulation group (p = 0.033, 95% CI = 0.265 - 5.220). Derived from these results the patients were dichotomized in two prediction groups with a cutoff at StimScore 11. Pearson Chi-Square revealed a significant correlation of dichotomized StimScore and final stimulation result with a correlation coefficient of 5.182 (p = .023).

Conclusions: To adopt electro-acupuncture as a percutaneous simulation method for PNS seemed to be feasible. The prediction of the response to PNS is crucial in order to minimize the number of patients implanted in vain, not only to protect the patient from unpromising surgery but also for economic reasons. The presented technique yields potential to meet these goals. While the number of patients is too small to draw final conclusions on the predictive value of PENS in PNS the presented results are coherent and deliver a starting point for further trials.