Dorsal Root Ganglion Stimulation Normalizes Measures of Pain Processing in Patients with Chronic Low‐Back Pain: A Prospective Pilot Study using Quantitative Sensory Testing

Abstract

Background Dorsal root ganglion stimulation (DRG‐S) is used as a treatment for chronic low‐back pain (CLBP), although its underlying mechanisms remain elusive. CLBP patients have been found to have reduced mechanoreceptive perception, reduced endogenous analgesia, as well as deep‐tissue hyperalgesia when compared with healthy controls. Using quantitative sensory testing (QST), we studied if DRG‐S in CLBP patients results in changes in pain processing. Methods Quantitative sensory testing was performed in patients before trial implantation of a DRG‐S system for CLBP and just before the trial lead removal or at 1‐month follow‐up after the permanent implant. We determined the pressure pain threshold (PPT) and mechanical detection threshold (MDT) at the most painful lower‐back location. PPT was also measured on the contralateral shoulder as a control. We obtained a measure of endogenous inhibitory pain modulation using conditioned pain modulation (CPM). Results We enrolled 11 patients (60 ± 16 years). Pain decreased from 8.5 ± 1.0 at baseline to 2.0 ± 1.5 on a 0‐10 numerical rating scale with DRG‐S (P < 0.01). From baseline to with DRG‐S, PPT on the most painful location on the low back increased from 28.7 ± 13.6 to 43.4 ± 17.2 N/cm2 (P < 0.01). MDT on the same location decreased from 8.1 ± 10.4 to 3.4 ± 4.7 mN (P = 0.07). PPT on the control location and CPM did not change significantly. Conclusions Our results suggest that DRG‐S in CLBP patients reduces deep‐tissue hyperalgesia in the low back, while improving mechanoreceptive perception. These changes in both neuropathic and nociceptive components of CLBP were accompanied by clinical improvements in pain and function.

Mechanisms for the Clinical Utility of Low-Frequency Stimulation in Neuromodulation of the Dorsal Root Ganglion

“…This very low frequency dependent nerve fiber type activation was recently demonstrated in the rodent model, where C fiber propagation into the dorsal horn was entrained up to 20 Hz, and further activation was not achieved up to 100 Hz (74). Additionally, it was demonstrated that hypersensitivity to mechanical stimulation normalizes with DRG‐S, a phenomenon recently demonstrated in patients implanted with DRG‐S using pressure pain threshold testing (74,75).…”

Dorsal root ganglion stimulation device explantation: A multicenter pooled data analysis

“…Early ambulation to decrease postoperative infections is an accepted practice that has repeatedly been demonstrated in systematic reviews 56,57 . DRG‐S has demonstrated greater improvements in physical function, as measured by disability scores, 21,58–62 compared to SCS 63–65 . Robust improvements in functional status may thus relate to low infection rates.…”

Lead migration and fracture rate in dorsal root ganglion stimulation using anchoring and non‐anchoring techniques: A multicenter pooled data analysis

“…A similar rapid appearance of migrations was observed in SCS and improved with anchor placement. 3,4 DRG-S has been shown to significantly improve function, 11,12,28,29 and likely led to a restoration of activities and quality of life shortly after implantation.…”