Dorsal Root Ganglion Stimulation for the Management of Intractable Painful Polyneuropathy: A Prospective Pilot Study

Objectives: Dorsal root ganglion stimulation (DRGS) is a promising neurostimulation modality in the treatment of painful polyneuropathy. The aim of this prospective pilot study was to investigate the effect of DRGS on pain intensity in patients with intractable painful polyneuropathy.Materials and Methods: Nine patients with chronic, intractable painful polyneuropathy in the lower limbs were recruited. In each subject, between two and four DRGS leads were placed at the level of the L5 and S1 dorsal root ganglion. If trial stimulation was successful, a definitive implantable pulse generator (IPG) was implanted. Pain intensity was scored using an 11-point numeric rating scale (NRS) and reported as median and interquartile range (IQR), and compared to baseline values using the Wilcoxon signed-rank test. Additionally, patients’ global impression of change (PGIC), pain extent, presence of neuropathic pain, physical functioning, quality of life, and mood were assessed.Results: Eight out of nine patients had a successful trial phase, of which seven received an IPG. Daytime pain decreased from a median (IQR) NRS score of 7.0 (5.9–8.3) to 2.0 (1.0–3.5) and 3.0 (1.6–4.9) in the first week and at six months after implantation, respectively. Similar effects were observed for night time and peak pain scores.Conclusions: The results of this study suggest that DRGS significantly reduces both pain intensity and PGIC in patients with intractable painful polyneuropathy in the lower extremities. Large-scale clinical trials are needed to prove the efficacy of DRGS in intractable painful polyneuropathy.     

Transgrade Dorsal Root Ganglion Stimulation as a Salvage Technique for Three Different Anatomical Barriers: A Case Series

BackgroundDorsal root ganglion stimulation (DRGS) is an effective treatment for complex regional pain syndrome (CRPS) and post-surgical neuropathic pain. However, some patients have surgical and anatomical conditions that are contraindications to traditional DRGS technique. A novel transgrade approach to DRGS placement has been described and demonstrated effective for post spine surgery patients. We present three patients, each with a different reason in which DRGS would not be accessible via the traditional anterograde approach, who all had successful DRGS transgrade placement.Materials and MethodsThe case series includes three patients with either CRPS or post-surgical neuropathic pain who had an anatomical or post-surgical condition that historically would have rendered DRGS contraindicated. Two patients had previously failed dorsal column stimulation. All three patients had successful placement with the transgrade approach—entry into the contralateral epidural space at the level of the targeted foramen from a cephalad angle. Each patient gave their verbal and written consent to be included in the case series.ResultsFollowing treatment with a transgrade approach, all three patients had significant pain relief and improvement in function without complication.ConclusionBarriers to anterograde foraminal access including previous implantation, previous instrumentation, and epidural adhesions may prevent DRGS placement in certain indicated patients. This can be especially challenging in patients who have failed other neuromodulation options like dorsal column stimulation. Our case series demonstrated that the transgrade technique can be successfully used in these cases to increase access to DRGS.     

Dorsal Root Ganglion Stimulation for Chronic Groin Pain: A Review

IntroductionChronic neuropathic groin pain develops in a significant number of postsurgical patients; however, multiple etiologies have been identified, and this makes it a challenging condition to treat. While treatment often involves a multimodal approach, advancements in neuromodulation technology, particularly dorsal root ganglion (DRG) stimulation, have benefited patients plagued by chronic pain refractory to standard treatment modalities. Our goal was to provide a definitive source of information for interventional pain physicians regarding groin pain and the use of DRG stimulation for its treatment.Materials and MethodsIn this narrative review, we provide an overview of groin pain and discuss potential pain generators. We also outline appropriate treatment options with particular interest on DRG stimulation. Lastly, we provide a narrative review of the published literature regarding DRG stimulation for chronic groin pain from a variety of etiologies.ConclusionDRG stimulation has emerged as an alternative neuromodulatory technique for patients with chronic groin pain. While previous studies suggest substantial sustained pain relief with DRG stimulation in this patient population, prospective randomized controlled studies are necessary before formal recommendations can be made.     

Endoscopic Lateral Approach for Dorsal Root Ganglion Burst Stimulation: Technical Note and Illustrative Case Series

IntroductionDorsal root ganglion (DRG) stimulation demonstrated superiority over traditional spinal cord stimulation with better pain relief and greater improvement of quality of life. However, leads specifically designed for DRG stimulation are difficult to implant in patients who previously underwent spinal surgery and show epidural scarring at the desired site of implantation because of the reduced stiffness of the lead. Nevertheless, recurrent leg or arm pain after spinal surgery usually manifests as a single level radiculopathy, which should theoretically be amenable to DRG stimulation.Materials and MethodsWe present the percutaneous transforaminal placement of cylindrical leads through a lateral endoscopic approach for DRG stimulation in burst mode.ResultsWe could successfully show that percutaneous transforaminal lead placement is feasible in three illustrative cases.ConclusionThis technical note combines two innovations, one linked to the other. The first innovation involves a novel endoscopic lateral transforaminal approach to insert a cylindrical lead to the DRG. Because this electrode is compatible with burst stimulation-enabled devices, a second innovation consists of the application of burst stimulation on the DRG.     

Analgesic Effects of Tonic and Burst Dorsal Root Ganglion Stimulation in Rats With Painful Tibial Nerve Injury

ObjectivesDorsal root ganglion (DRG) stimulation is effective in treating chronic pain. While burst stimulation has been proven to enhance the therapeutic efficacy in spinal cord stimulation, currently only a tonic stimulation waveform is clinically used in DRG stimulation. We hypothesized that burst DRG stimulation might also produce analgesic effect in a preclinical neuropathic pain model. We evaluated both the therapeutic effects of burst DRG stimulation and the possible effects of DRG stimulation upon inflammation within the DRG in a preclinical neuropathic pain model.Materials and MethodsRats received either a painful tibial nerve injury or sham surgery. Analgesic effects of DRG stimulation were evaluated by testing a battery of evoked pain-related behaviors as well as measuring the positive affective state associated with relief of spontaneous pain using conditioned place preference. Histological evidence for neuronal trauma or neuroinflammation was evaluated.ResultsAll of the waveforms tested (20 Hz-tonic, 20 Hz-burst, and 40 Hz-burst) have similar analgesic effects in sensory tests and conditioned place preference. Long-term DRG stimulation for two weeks does not change DRG expression of markers for nerve injury and neuroinflammation.ConclusionsDRG stimulation using burst waveform might be also suitable for treating neuropathic pain.     

Effect of Patient Characteristics on Clinical Outcomes More Than 12 Months Following Dorsal Root Ganglion Stimulation Implantation: A Retrospective Review

IntroductionDorsal root ganglion (DRG) stimulation is an effective treatment option for lower extremity complex regional pain syndrome and other focal pain conditions. However, the patient characteristics that may predict long-term outcomes have not been defined.Materials and MethodsThis was a retrospective observational study that included 93 patients who were implanted with a DRG stimulator at a single private practice institution. A variety of demographic data was collected. Follow-up results were reviewed from multiple time points more than 12 months. Patients were classified as either “responder” or “nonresponder” status using two different thresholds, “greater than or equal to 50% pain relief” and “greater than or equal to 80% pain relief.”Results: A history of prior chronic opioid use was associated with significantly lower rates of responder status based on both a 50% pain relief threshold and 80% pain relief threshold at the one week to one month, three months, and 12-months visits.ConclusionsThis single-center retrospective study found patients prescribed chronic opioids at the time of DRG stimulator implantation had a higher likelihood of less than 50% pain relief and 80% pain relief at one month, three months, and 12 months follow-up visits.     

Dorsal Root Ganglion Stimulation for the Treatment of Non-Complex Regional Pain Syndrome Related Chronic Pain Syndromes: A Systematic Review

Background: While the majority of indications and approvals for dorsal root ganglion stimulation (DRGS) are for the refractory management of complex regional pain syndrome (CRPS), emerging evidence has suggested that DRGS may be favorably used for a plethora of other chronic pain phenomena. Consequently, we aimed to characterize the use and efficacy of DRGS for these non–CRPS-related chronic pain syndromes.Materials and Methods: A systematic review of clinical studies demonstrating the use of DRGS for non–CRPS-related chronic pain syndromes. The literature search was performed using PubMed, Cochrane Library, and CINAHL plus across August and September 2020.Results: A total of 28 reports comprising 354 total patients were included in the analysis. Of the chronic pain syndromes presented, axial low back pain, chronic pelvic and groin pain, other peripheral neuropathies, and studies with multiple concomitant pain syndromes, a majority demonstrated >50% mean pain reduction at the time of last follow-up following DRGS. Physical function, quality of life (QOL), and lesser pain medication usage also were repeatedly reported to be significantly improved.Conclusions: DRGS continues to lack supportive evidence from well designed, high level studies and recommendations from consensus committee experts. However, we present repeated and consistent evidence from lower level studies showing success with the use of DRGS for various non-CRPS chronic pain syndromes in reducing pain along with increasing function and QOL from one week to three years. Due to such low-level, high bias evidence, we strongly encourage the continuation of high-level studies in order to provide a stronger foundation for the use of DRGS in non-CRPS chronic pain patients. However, it may be reasonable and appropriate to evaluate patients for DRGS candidacy on a case-by-case basis particularly if they manifest focal pain syndromes refractory to noninterventional measures and may not be ideal candidates for other forms of neuromodulation.     

Dorsal Root Ganglion Stimulation as a Salvage Therapy Following Failed Spinal Cord Stimulation

IntroductionSpinal cord stimulation (SCS) can provide long-term pain relief for various chronic pain conditions, but some patients have no relief with trial stimulation or lose efficacy over time. To “salvage” relief in patients who do not respond or have lost efficacy, alternative stimulation paradigms or anatomical targets can be considered. Dorsal root ganglion stimulation (DRG-S) has a different mechanism of action and anatomical target than SCS.ObjectivesWe assessed DRG-S salvage therapy outcomes in patients who did not respond to SCS or had lost SCS efficacy.Materials and MethodsWe retrospectively included consecutive patients from 2016 to 2020 who were salvaged with DRG-S after failed SCS trials (<50% pain reduction) or who had lost efficacy after permanent SCS. We compared numerical rating scale (NRS) pain, Oswestry disability index (ODI), health-related quality of life (EuroQol five-dimensions five-level), and oral morphine equivalent (OME) opioid requirements before DRG-S salvage and at patients’ last follow-up.ResultsA total of 60 patients who had failed SCS were salvaged with DRG-S. The mean age was 56 ± 12 years, and the most common diagnoses were complex regional pain syndrome (n = 24) and failed back surgery syndrome (n = 24). The most common failed modalities included tonic (n = 32), Burst (n = 18), and high-frequency (n = 10) SCS. The median follow-up duration of salvage DRG-S was 34 months. With DRG-S, NRS decreased (8.7 ± 1.2 to 3.8 ± 2.1), and OME declined (median 23 mg to median 15 mg), whereas EuroQol 5D scores increased (0.40 ± 0.15 to 0.71 ± 0.15), and ODI improved (64 ± 14% to 31 ± 18%) (all p < 0.05).ConclusionsDRG-S can be used in patients with chronic pain who have previously failed to receive persistent benefit from SCS.