FV 11. Restoration of laser evoked potentials (LEP) in patients receiving Dorsal Root Ganglion (DRG) stimulation for chronic localized neuropathic pain

Abstract

Objective Chronic neuropathic pain is difficult to treat. Recently, a novel target for neuromodulation, the DRG, has been shown to be effective in managing neuropathic pain. However, the mechanisms underlying the impact of DRG stimulation are not well established. Therefore, we want to assess LEP’s for the quantification of the effects of DRG stimulation on pain processing. Methods Patients implanted with a DRG stimulator (Spinal Modulation, Inc., Menlo Park, CA, USA) in order to manage chronic unilateral neuropathic pain of the groin were enrolled in the study. LEP assessment was performed with DRG stimulation in ON and OFF phases. The measurements were performed immediately after DRG stimulator implantation (T0) and repeated after one month (T1) and six months (T2). Pain intensity was assessed by Numerical Rating Scale (NRS). The questionnaires PDI, BPI, NPSI, Pain-Detect and SF-36 were also evaluated. Quantitative sensory tests (QST) were also performed. Results We examined 9 patients prospectively (4 female, 5 male, mean age 53 years, age range 48–63 years). The major findings show a reduction in the mean pain from NRS 8.4 ± 0.48 to 2.4 ± 1.49 during DRG stimulation (OFF T0 vs. ON T2, p ± 3.64 (T0) to 10.96 ± 4.19 (T2) in 6 months (p 0,05, n = 5, U-Test). Conclusions DRG stimulation is an effective method in order to relieve chronic localized neuropathic pain. Our data suggests that DRG stimulation can induce plastic changes in the pain pathways, restoring normal pain processing, thus causing pain reduction. Restoration of the LEP’s may also relate to a better clinical outcome.