A Novel Mini-invasive Approach to the Treatment of Neuropathic Pain: The PENS Study.

BACKGROUND Peripheral neuromodulation is often used as chronic neuropathic pain treatment. Percutaneous electrical nerve stimulation (PENS) is generally utilized with several probes at the same time and repeated treatments. OBJECTIVES Evaluate the short- and long-term efficacy of a single probe and single shot PENS approach. STUDY DESIGN Multicenter, prospective, observational study. SETTING Four Italian pain therapy centers. METHODS Inclusion criteria were age = 18 and = 80 years, presence of severe peripheral neuropathic pain lasting more than 3 months, localized and refractory to pharmacological therapies. Patients with infection, coagulopathies, psychiatric disorders, pacemakers, or implantable cardiac defibrillators were excluded. PATIENTS Seventy-six patients (47 women, 29 men), mean age 62 ± 14 years, affected by neuralgia (21 herpes zoster infection, 31 causalgia, 24 postoperative pain) were enrolled in the study. INTERVENTION After localization of trigger point and/or allodynic/hyperalgesic area, PENS therapy was achieved with a single 21 gauge conductive probe tunneled percutaneously and a neurostimulator device. MEASUREMENT Numerical Rating Scale (NRS) and Neuropathic Pain Scale (NPS) were assessed at baseline, 60 minutes after PENS, at one week, after one, 3, and 6 months; perceived health outcome was measured with Euroqol-5 dimension (EQ-5D) questionnaire at baseline and at 6 months. Adverse events and patient satisfaction were reported. RESULTS NRS and NPS decreased significantly after 60 minutes and the reduction remained constant over time at follow-up. EQ-5D increased significantly with respect to the baseline. Two nonclinically significant adverse events (one contralateral dysestesia and one self-resolving hematoma) were observed. LIMITATIONS Small sample size and non-randomized observational study; high prevalence of post-herpetic and occipital neuralgias. CONCLUSION PENS therapy produced significant and long-lasting pain relief in chronic peripheral neuropathic pains of different etiology. The present study confirms the feasibility, safety, and repeatability of this minimally invasive technique.