Transcutaneous Peripheral Nerve Stimulation for the Treatment of Neuropathic Pain in the Upper Limb

Background: A small number of patients develop intractable peripheral nerve pain following injury or surgery to the upper limb that is refractory to pharmacological treatment. This study reports our results of using transcutaneous peripheral nerve stimulation (TPNS), a non-invasive form of neuromodulation, to treat this difficult problem.

Methods: Seventy-two patients were treated for intractable pain in the upper limb using this technique. Electrical current was delivered transcutaneously through a handheld probe, placed on the skin overlying the affected peripheral nerve proximal to the site of pain. Pain severity was determined before and immediately after treatment by subjective patient self-assessment using a visual analogue pain scale. Pre-post treatment changes in pain severity were analysed by Student's test for paired data. Outcome in respect of overall effectiveness of this treatment, was graded according to the maximum duration of pain relief achieved.

Results: Overall, TPNS reduced pain intensity from 8.4 (SD 1.6) before treatment to 4.2 (SD 3.5) immediately after treatment, a highly significant effect ($p<0.001$). The treatment achieved cure in 8/72 (11%) of our patients and a useful therapeutic outcome (pain relief ≥ 1 day) in 27/72 (38%). The treatment failed in 37/72 (51%).

Conclusions: TPNS warrants consideration as a therapy for neuropathic pain in the upper limb after drug treatment has failed and before offering surgery or spinal root stimulation.