Long-Term Treatment of Chronic Neuropathic Pain Using External Noninvasive External Peripheral Nerve Stimulation in Five Patients

Background: External noninvasive peripheral nerve stimulation (EN-PNS) is a neuromodulation technique in which a lowfrequency electrical stimulation is applied via a ball-shaped electrode that is placed directly onto the skin. Objectives: To examine how this modality is being used in the long term, by patients with chronic neuropathic pain who had responded to this treatment in a short-term trial. Materials and Methods: All patients with a diagnosis of neuropathic pain who had obtained a machine for continued long-term use (via special funding requests), following a successful trial between 2009 and 2012 were contacted. A successful trial was considered as > 50% pain reduction, duration of any beneficial treatment effect >= 12 hours, and improvements to function/reduced medication use. Data were collected from case notes and a telephone interview. Results: Thirteen trials were recorded successful, out of 21 conducted. Eleven individual funding applications were made, of which seven were successful. Five patients were contactable. All reported continued stimulator use at follow-up (average = 3.5 years) and ongoing pain relief associated with treatment. Pain intensities (numerical rating scale 0-10) had reduced in all five cases when baseline scores were compared with follow-up scores; average pain 5.6-3.5 and worst pain 8.6-4.8. All patients reported a reduction in frequency of pain flare-ups during device use. Conclusion: Patients reported EN-PNS to provide ongoing benefit at long-term follow-up. Further prospective investigations are justified.