Effectiveness of "Transgrade" Epidural Technique for Dorsal Root Ganglion Stimulation. A Retrospective, Single-Center, Case Series for Chronic Focal Neuropathic Pain.

Background: The recent interest in targeting the dorsal root ganglion (DRG) has led to the development of new techniques of electrode placement. In this article, we describe a new "Transgrade" approach to the DRG, accessing the contralateral interlaminar space and steering the lead out the opposite foramen.
Objectives: The purpose of this study was to evaluate the Transgrade technique to the DRG in the management of focal neuropathic pain, predominately complex regional pain syndrome in terms of efficacy and safety.
Study Design: A retrospective, observational review of all patients selected for DRG stimulation using the Transgrade technique to the DRG.
Setting: Pain Management and Neuromodulation Centre, Guys and St. Thomas NHS Foundation Trust, London, United Kingdom.
Methods: Data were taken from a hospital password-protected database. All patients were contacted by telephone for Numeric Rating Scale (NRS-11) score, Patient Global Impression of Change (PGIC) score, and complications. A patient responder was defined as having a PGIC score of 6 or 7, and a 2-point reduction from baseline NRS-11.
Results: A total of 39 patients (46% women) with a mean age of 46 years (± 2) underwent a trial of DRG stimulation that resulted in an implantation rate of 82% (32 of 39). The responder rates, according to NRS-11 and PGIC results, were 87% (28 of 32) at 6 weeks and 66% (21 of 32) at a mean of 18 months (± 1.8) follow-up. Pocket pain was the most common complication, occurring in 7 of 32 (22%) patients, and the lead migration rate was 3 out of 57 leads placed (5.2%). A burst protocol was the favored method of stimulation in the majority of patients, 25 of 32 (78%).
Limitations: Retrospective nature of design, small sample size.
Conclusions: The Transgrade technique of placing DRG leads offers an alternative method that is safe and effective. New methods of stimulation to the DRG offer more choice and potentially better efficacy for patients with chronic neuropathic pain.
Key Words: Neuromodulation, dorsal root ganglion, neuropathic pain, complex regional pain syndrome, spinal cord stimulation, chronic pain, implantable neurostimulators, spinal nerve root stimulation.