gms | German Medical Science

Objective: Peripheral nerve field stimulation (PNFS) is an effective alternative treatment option for patients if conventional therapy does not provide adequate relief of intractable chronic low back pain. Physical therapy with transcutaneous electrical nerve stimulation (TENS) is known for its easy application and thus frequently used in the multimodal pain therapy concept. The aim of this prospective study was to examine TENS use and its impact for later successful PNFS in a follow up of 3 months.

Methods: Between 2014 and 2016 a prospective cohort study of 12 patients with chronic lumbar pain was conducted. All patients were treated with multiple pain medications. Pain intensity (NRS), activity level and health-related quality of life (SF12v2 score), and Oswestry Disability Index (ODI) were assessed before and after TENS use, pre- and postoperatively as well as 3 months after neuromodulative treatment. TENS was applied for 3-5 days. The implantation of a rechargeable PNFS-system with 2 percutaneous leads was performed after 4-7 days of positive testing. Statistical analysis was performed using the Mann-Whitney U and the Wilcoxon rank-sum test.

Results: The cohort consisted of 12 patients (5 females, 7 males) with a median age of 60.3 years (range 50.3-75.4). Overall median numerical rating scale (NRS) preoperatively was 7.5 (range 6-10). Overall median ODI before treatment was 51 (range 26-76). SF12v2 indicated a reduced activity level and lowered quality of life. After positive PNFS testing a neurostimulator was implanted in 4 patients with positive TENS effect and 5 patients with no TENS effect. Three patients had no PNFS effect and the test electrode was explanted. After 3 months median overall NRS was reduced to 3.5 (range 0-9). Overall median ODI improved to 42 (range 14-76). In the TENS positive cohort NRS was reduced from 8 (range 6-9) to 2.5 (range 0-3), ODI from 63 (range 56-68) to 34 (range 14-42). In the TENS negative cohort NRS was reduced from 7 (range 6-10) to 5 (range 3-9). There was no improvement from initial ODI 45 (range 26-76) to 46 (range 26-76) after 3 months. SF12v2 showed a better improvement in the TENS positive cohort. These results showed no statistical significance (p>0.05).

Conclusion: This interim analysis shows that PNFS is effective and safe in treating intractable chronic low back pain. TENS seems to have some predictive value for the patient selection in PNFS, as TENS positive patients showed a more effective treatment effect with a greater reduction of NRS, ODI and SF12v2. These preliminary results have to be confirmed in a larger study cohort.