Comparing the efficacy of targeted spinal cord stimulation (SCS) of the dorsal root ganglion with conventional medical management (CMM) in patients with chronic post-surgical inguinal pain: the SMASHING trial

BACKGROUND A significant number of patients who undergo a standard inguinal hernia repair or a Pfannenstiel incision develop chronic (> 3 months) post-surgical inguinal pain (PSIP) due to nerve entrapment. If medication or peripheral nerve blocks fail, surgery including neurectomies may offer relief. However, some patients do not respond to any of the currently available remedial treatment modalities. Targeted spinal cord stimulation (SCS) of the dorsal root ganglion (DRG) is a relatively new type of therapy that has a potential to significantly reduce chronic PSIP. The Axium® SCS System (Spinal Modulation Inc., NY, USA) has been shown to be safe and successful in small cohorts of PSIP patients. Aim of this study is to evaluate targeted spinal cord stimulation therapy in patients with PSIP. METHODS A prospective, multicentre, randomized controlled trial with optional one-way crossover will assess the efficacy of the Axium® SCS system for the treatment of PSIP. Seventy-eight patients with intractable PSIP following open hernia repair or Pfannenstiel incision who did not respond favorably to previous pain treatment regimens including a neurectomy will be randomized to either an Axium® SCS arm or a control arm receiving only conventional medical management (CMM). Primary outcome is the difference in percentage of subjects with ≥50% pain relief after 6 months using a Numerical Pain Rating Scale (NPRS). Data are collected using a daily pain/sleep diary and a number needed to treat (NNT) analysis is performed. Various secondary outcomes will be collected. DISCUSSION Targeted SCS stimulation of the DRG using the Axium® SCS system will possibly offer significant pain reduction in patients with PSIP who are refractory to other treatment modalities. TRIAL REGISTRATION The study protocol is registered at the NIH Clinical Trials Registry ( http://clinicaltrials.gov , ClinicalTrials.gov identifier: NCT02349659 ) on January 29, 2015.