Dorsal Root Ganglion Stimulation in Chronic Painful Polyneuropathy: A Potential Modulator for Small Nerve Fiber Regeneration

OBJECTIVES: Neuromodulatory treatments like spinal cord stimulation and dorsal root ganglion stimulation (DRGS) have emerged as effective treatments to relieve pain in painful polyneuropathy. Animal studies have demonstrated that neurostimulation can enhance nerve regeneration. This study aimed to investigate if DRGS may impact intraepidermal nerve fiber regeneration and sensory nerve function.

MATERIALS AND METHODS: Nine patients with chronic, intractable painful polyneuropathy were recruited. Intraepidermal nerve fiber density (IENFD) quantification in 3 mm punch skin biopsy was performed 1 month before DRGS (placed at the level of the L5 and S1 dorsal root ganglion) and after 12- and 24-month follow-up. Quantitative sensory testing, nerve conduction studies, and a clinical scale score were also performed at the same time points.

RESULTS: In 7 of 9 patients, DRGS was successful (defined as a reduction of ≥ 50% in daytime and/or night-time pain intensity), allowing a definitive implantable pulse generator implantation. The median baseline IENFD among these 7 patients was 1.6 fibers/mm (first and third quartile: 1.2; 4.3) and increased to 2.6 fibers/mm (2.5; 2.9) and 1.9 fibers/mm (1.6; 2.4) at 1- and 2-years follow-up, respectively. These changes were not statistically significant (p = 1.000 and 0.375). Sensory nerve tests did not show substantial changes.

CONCLUSIONS: Although not significant, the results of this study showed that in most of the patients with implants, there was a slight increase of the IENFD at the 1- and 2-year follow-up. Larger-scale clinical trials are warranted to explore the possible role of DRGS in reversing the progressive neurodegeneration over time.

CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT02435004; Swiss National Clinical Trials Portal: SNCTP000001376.