A Literature Review of Dorsal Root Entry Zone Complex (DREZC) Lesions: Integration of Translational Data for an Evolution to More Accurate Nomenclature

Scientific and Regulatory Policy Committee Technical Review: Biology and Pathology of Ganglia in Animal Species Used for Nonclinical Safety Testing

Dorsal root ganglia (DRG), trigeminal ganglia (TG), other sensory ganglia, and autonomic ganglia may be injured by some test article classes, including anti-neoplastic chemotherapeutics, adeno-associated virus-based gene therapies, antisense oligonucleotides, nerve growth factor inhibitors, and aminoglycoside antibiotics. This article reviews ganglion anatomy, cytology, and pathology (emphasizing sensory ganglia) among common nonclinical species used in assessing product safety for such test articles (TAs). Principal histopathologic findings associated with sensory ganglion injury include neuron degeneration, necrosis, and/or loss; increased satellite glial cell and/or Schwann cell numbers; and leukocyte infiltration and/or inflammation. Secondary nerve fiber degeneration and/or glial reactions may occur in nerves, dorsal spinal nerve roots, spinal cord (dorsal and occasionally lateral funiculi), and sometimes the brainstem. Ganglion findings related to TA administration may result from TA exposure and/or trauma related to direct TA delivery into the central nervous system or ganglia. In some cases, TA-related effects may need to be differentiated from a spectrum of artifactual and/or spontaneous background changes.

Review of Opioid Sparing Interventional Pain Management Options and Techniques for Radiofrequency Ablations for Sacroiliac Joint Pain

PURPOSE OF REVIEW

The goal of this clinical review was to provide an update about the existing treatment options and associated evidence for various radiofrequency ablation techniques for sacroiliac joint pain. An electronic literature search on radiofrequency for the treatment of sacroiliac joint pain was conducted using PubMed, NCBI and Google Scholar. The following search keywords were used: radiofrequency ablation (cooled, pulsed, conventional, bipolar, intra-articular), sacroiliac joint and sacroiliac pain. The search was limited to human subjects, English language and articles with available full text. The bibliographic sections of all manuscripts were further searched for additional relevant citations. The full text of the relevant articles was reviewed by all the authors.

RECENT FINDINGS

Our study showed that radiofrequency ablation is a safe and effective treatment option that can be utilized to manage sacroiliac joint pain. It offers accessibility to the primary care physician, reduces office visits with "pain" as the primary complaint and provides the added benefit of acting as a non-opioid sparing means of analgesia.

Clinical Radiofrequency Ablation Outcomes of Combined Sensory Nerve Branch and Dorsal Entry Root Zone Complex Lesions for Sacroiliac Joint Complex Pain

BACKGROUND

Chronic lower back pain (LBP) with or without leg pain (LP) is the most commonly reported anatomical site of pain among Canadian adults with chronic pain. A common cause for LBP and LP arises from dysfunction of the sacroiliac joint (SIJ) complex. When conventional medical management or rehabilitative efforts for SIJ-related LBP and LP fail to provide analgesia, pulsed radiofrequency (PRF) and/or radiofrequency ablation (RFA) of the dorsal entry root zone complex lesions (DREZC) and/or their more peripheral branches can also be a suitable means for treatment. Both PRF and RFA are interventional techniques that utilize heat to attenuate or ablate transmission of painful signals, respectively. The purpose of this chart review is to explore the clinical outcomes of patients experiencing SIJ-related pain who have undergone procedures with combined sensory nerve branch RFA and DREZC PRF lesions targeting the SIJ complex.

METHODS

Following institutional review board approval, a retrospective chart review was performed from June 2018 to February 2021 for patients with LBP and/or LP refractory to physical rehabilitative efforts and medical management that underwent combined PRF and RF treatments for a diagnosis of SIJ complex pain. RF and PRF procedures were anatomically guided with the addition of sensory stimulation to ensure appropriate needle placement. Charts were reviewed for percentage of analgesia at final follow-up, duration of effect, degree of analgesia, patients' functional improvements, and changes in medication use patterns.

RESULTS

Data was reviewed from 180 patients with LBP or LP who underwent combined PRF and RF treatments for a diagnosis of SIJ complex pain. The group consisted of 69 men and 111 women with a mean age of 59 years. All patients had lesions to their dorsal roots and/or branches (lumbar medial and sacral lateral), as determined using their pain profile as well as sensory stimulation. In the sample of 180 patients a total of 276 SIJs were treated over the period of data collection. Overall, 85.0% (n = 234) of procedures were considered successful with more than 50% analgesic relief at final follow-up. Of 234 successful outcomes, 110 reported ongoing analgesia (mean = 80.3% pain relief, SD ± 18.0) on the last date of follow up (mean = 53.2 days, SD ± 41.8) prior to being lost to follow-up. For patients not lost to follow-up, the mean amount of analgesia was reported to be 83.9% with an average duration of 86.3 days. Among all treatments, 6.9% (n = 19) provided no analgesic effect. Among the successful procedure outcomes, 54.4% (n = 150) reported increased activity/mobility, 24.3% (n = 67) reported improved sleep, 49.3% (n = 136) reported improved mood, and 11.6% (n = 32) reported decreased medication usage. Nine patients reported complications following the procedure. Complications included transient soreness, bruising, tenderness, myofascial pain, and two mild vagal responses without lasting sequelae.

CONCLUSION

This review suggests that combined sensory nerve branch RFA and DREZC PRF lesions targeting the SIJ complex is a suitable intervention to treat SIJ-related LBP and/or LP refractory to physical rehabilitative efforts and medical management. Approximately 85% of these cases were successfully treated with the majority of patients report lasting analgesic effects with minimal complications, supporting the use of sensory stimulation-guided combined RF and PRF lesions for treatment of refractory SIJ complex pain.

Safety of Conventional and Pulsed Radiofrequency Lesions of the Dorsal Root Entry Zone Complex (DREZC) for Interventional Pain Management: A Systematic Review

Study Design

Systematic literature review.

Objective

The goal of this systematic review is to assess the clinical safety and potential complications of conventional and pulsed radiofrequency ablations targeting dorsal root entry zone complex (DREZC) components in the treatment of chronic pain.

Background

There is a growing popularity for the use of radiofrequency ablation (RFA) techniques targeting DREZC components by pain management physicians for an increasing variety of indications. To date, we lack a systematic review to describe the safety and the type of complications associated with these procedures.

Methods

This was a systematic literature review. This systematic search was limited to peer-reviewed literature using “radiofrequency ablation” as a search keyword using PubMed’s database for manuscripts published between inception and December 2020. Abstracts that involved the application of radiofrequency currents, of any modality, to DREZC components for the treatment of pain were included for full-text review. Search was limited to original data describing clinical outcomes following RFA performed for pain indications only, involving the DREZC components outlined above, in human subjects, and written in English. The primary outcomes were complications associated with conventional RFA and pulsed radiofrequency ablation (PRF). Complications were categorized as type 1 (persistent neurological deficits or other serious adverse events, defined as any event that resulted in permanent of prolonged injury; type 2 (transient neuritis or neurological deficits, or other non-neurological non-minor adverse event); type 3 (minor adverse events (e.g., headache, soreness, bruising, etc.).

Results

Of the 62 selected manuscripts totaling 3157 patients, there were zero serious adverse events or persistent neurological deficits reported. A total of 36 (1.14%) transient neurological deficits, cases of transient neuritis, or non-minor adverse events like uncomplicated pneumothorax were reported. A total of 113 (3.58%) minor adverse events were reported (bruising, transient site soreness, headache).

Conclusions

This systematic review indicates that the use of RFA lesion of the DREZC for interventional pain management is very safe. There were no serious adverse effects with a sizable sample of randomized controlled trial (RCT), prospective observational, and retrospective studies.

Radiofrequency Ablation of the Superior Cluneal Nerve: A Novel Minimally Invasive Approach Adopting Recent Anatomic and Neurosurgical Data

Objectives/Introduction

Superior cluneal neuralgia (SCN) is a distinct cause of lower back and/or leg pain related to pathology of the superior cluneal nerve (SCn). SCN has been termed pseudo-sciatica and is an overlooked differential diagnosis when patients are otherwise presenting with low back and/or radicular pain. Radiofrequency ablation (RFA) is commonly used for denervation of the medial branches of the dorsal root for facet joint syndrome for sacroiliac joint; however, RFA has not been described to ablate the SCn for SCN. Herein, we present a novel interventional minimally invasive approach using RFA of the SCn for SCN in a series of 46 patients.

Methods

Institutional review board approved retrospective chart review was used to collect data for all SCn RFA cases from January 1, 2018, to February 8, 2021. Fluoroscopically guided SCn ablations were performed for patients with a positive “iliac crest point sign,” reproductive of their back and leg pain during physical examination. Sensory stimulation was utilized to confirm RF cannula-probe placement adjacent to the SCn, and motor testing was used to confirm no distal motor response prior to monopolar RF ablation with a Halyard RF Generator (100 mm curved 22G 10 mm active tip RF cannulae). Charts were reviewed for time of analgesia follow-up, duration and degree of analgesia, improvements in patients’ functional capacity, and changes in medication.

Results

Data were reviewed for 51 patients who underwent Scn RFA, 5 of which were lost to follow-up. The remaining 46 patients consisted of 29 women and 17 men with a mean age of 59.4 years; 78.3% (n = 36) had ongoing relief at a mean of 92.1 days follow-up, ranging from 13 to 308 days, with a mean of 92.3% analgesia (SD 15.0%). At a mean of 111.2 days of follow-up, ranging from 42–201 days, 21.7% (n = 10) of patients reported that their pain had returned and had 95% analgesia during that time period (SD 6.7%); 41.3% (n = 19) reported improved activity/gait, 17.4% reported improved mood (n = 8), and 8.7% reported decreased medication use (n = 4). Five patients had minor complications including bruising (1), 2–3 days of soreness on site (2), myofascial pain (1), and quadratus lumborus muscle spasm relieved with trigger point injection (1).

Conclusions

This is the first report of both technique and outcomes for radiofrequency ablation of superior cluneal neuralgia. This series suggests that RFA of the SCn is a suitable intervention for the treatment of SCN; 21.7% of patients reported a mean of 95% analgesia for a mean duration of 111.2 days, and the remaining 78.3% of patients reported ongoing relief with a mean of 92.3% analgesia at last follow-up (mean 92.1 days). There were no serious adverse events.