Dorsal root ganglion stimulation for the treatment of chronic pelvic pain: A systematic review

Improved Selectivity in Eliciting Evoked Electromyography Responses With High-Resolution Spinal Cord Stimulation

BACKGROUND AND OBJECTIVES

As spinal cord stimulation (SCS) offers a therapy for increasing numbers of patients with chronic pain and spinal cord injury, it becomes increasingly important to better understand its somatotopy. In this prospective study, we investigate whether high-resolution SCS (HR-SCS) offers improved selectivity assessed through elicitation of evoked electromyography (EMG) responses as compared with commercial paddle leads.

METHODS

Vertical tripole configurations were used to elicit EMG responses in both types of paddles placed for standard-of-care indications between T6 and T10. In HR-SCS, evoked EMG responses in lower extremity/abdominal muscle groups were monitored at 6 to 8 mediolateral sites. All commercial paddle columns were tested. Percentage change in the maximum root mean square value was calculated at a group level. Heat maps were generated to identify responders for each muscle group. Responders were considered patients who had a >50% change in root mean square over baseline.

RESULTS

We demonstrated significantly greater motor responses across medial and lateral contacts and greater responder rates consistently at the T6 and T9 levels with HR-SCS as compared with commercial paddles in 18 patients. Distal muscle groups (gastrocnemius and tibialis anterior) and proximal muscle groups (biceps femoris and quadriceps) were selectively activated at both levels.

CONCLUSION

We demonstrate that HR-SCS has greater selectivity in eliciting evoked EMG responses in an intraoperative setting. HR-SCS offers recruitment of muscle groups at lateral contacts concurrently with medial contacts. We provide data that HR-SCS may provide higher spatial resolution, which has the potential to allow for personalization of care and treatment of pain syndromes/symptoms which to date have not been effectively treated.

Mechanisms of Action of Dorsal Root Ganglion Stimulation

The dorsal root ganglion (DRG) serves as a pivotal site for managing chronic pain through dorsal root ganglion stimulation (DRG-S). In recent years, the DRG-S has emerged as an attractive modality in the armamentarium of neuromodulation therapy due to its accessibility and efficacy in alleviating chronic pain refractory to conventional treatments. Despite its therapeutic advantages, the precise mechanisms underlying DRG-S-induced analgesia remain elusive, attributed in part to the diverse sensory neuron population within the DRG and its modulation of both peripheral and central sensory processing pathways. Emerging evidence suggests that DRG-S may alleviate pain by several mechanisms, including the reduction of nociceptive signals at the T-junction of sensory neurons, modulation of pain gating pathways within the dorsal horn, and regulation of neuronal excitability within the DRG itself. However, elucidating the full extent of DRG-S mechanisms necessitates further exploration, particularly regarding its supraspinal effects and its interactions with cognitive and affective networks. Understanding these mechanisms is crucial for optimizing neurostimulation technologies and improving clinical outcomes of DRG-S for chronic pain management. This review provides a comprehensive overview of the DRG anatomy, mechanisms of action of the DRG-S, and its significance in neuromodulation therapy for chronic pain.

Dorsal root ganglion stimulation for patients with chronic pelvic pain: A retrospective review of patient experiences and long-term outcomes

Introduction

Chronic pelvic pain (CPP) is a refractory condition that has physical, emotional, and financial impacts on patients. Dorsal root ganglion stimulation (DRGS) is a promising interventional modality for patients with refractory CPP, however studies of long-term outcomes are limited. We aim to present the results from a retrospective review of 31 patients with CPP treated using DRGS.

Materials and methods

IRB approval was obtained. A retrospective chart review was conducted, including 31 patients who underwent a DRGS trial between 2017 and 2022 at two academic centers. Pain history, trial/implant lead configuration, complications/revisions, pain scores, functional goals, and medication use were recorded.

Results

Thirty-one patients with CPP underwent a 7-10 day DRGS trial between 2017 and 2022. Of the 31 patients, 21 (68%, CI 50-81%) had a successful trial, defined as >50% reported pain relief. Twenty patients underwent DRGS implantation. Average follow-up was 28.2 ± 17.3 months. Nine patients (45%) required revision surgery for lead migration or fracture. Thirteen patients remain implanted with an average reported percent relief of 55 ± 15%. Seven patients were explanted (35%), with an average time to explant of 12.5 ± 3 months.

Conclusions

This study presents one of the largest groups of patients with DRGS for the treatment of CPP. The results highlight the variable experiences of patients after DRGS trial/implant. We report on the incidence of lead migration and fracture, sparingly described in the literature. Larger, prospective studies are needed to elucidate which patients with CPP may benefit most from DRGS, and to better understand the incidence and implications of complications.

Neuromodulation Techniques in Chronic Refractory Coccydynia: A Narrative Review

Refractory coccydynia is a condition characterized by severe coccygeal pain and poses a challenging management dilemma for clinicians. Advancements in neuromodulation (NM) technology have provided benefits to people experiencing chronic pain that is resistant to standard treatments. This review aims to summarize the spectrum of current NM techniques employed in the treatment of refractory coccydynia along with their effectiveness. A review of studies in the scientific literature from 2012 to 2023 was conducted, revealing a limited number of case reports. Although the available evidence at this time suggests significant pain relief with the utilization of NM techniques, the limited scope and nature of the studies reviewed emphasize the need for large-scale, rigorous, high-level research in this domain in order to establish a comprehensive understanding of the role of NM and its effectiveness in the management of intractable coccydynia.