Diagnostic Facet Joint Injections
Due to the lack of reliable history, physical exam, or imaging to predict response, providers must rely on facet interventions diagnostic injections given for diagnostic purposes to determine if the facet joint is the source of suspected spinal pain. There is controversy over optimal patient selection for diagnostic injections, which measures successful response and type and number of diagnostic injections performed.
Numerous investigations have been undertaken to correlate symptoms and physical exam findings with facet pathology and have concluded conventional clinical findings are unreliable in identifying facet joint success.4,8,16 A 2020 summary of the literature by Cohen et al “Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group” included 21 studies evaluating the association of physical exam findings with facet block results, and concluded there was no historical or physical exam findings that could reliably predict response to facet joint blocks, grade C evidence, low level of certainty.4 This is consistent with ASIPP 2020 Comprehensive Evidence-Based Guidelines for Facet Joint Interventions in the Management of Chronic Spinal Pain: American Society of Interventional Pain Physicians (ASIPP) Guidelines (2020 ASIPP Guidelines) which rated accurate diagnosis of facet joint pain with physical examination and symptoms level IV with a weak strength of recommendation.8 2020 NASS Guidelines reported insufficient evidence to make a recommendation for or against patient reported reproduction of pain during a facet joint injection as a predictor of response to dual diagnostic blocks with a grade 1 recommendation.5, 8 A careful medical history and exam remain an important component to the evaluation of other etiologies of low back pain and raise suspicion of facet source.8 Physical findings can help identify levels for blocks and maneuvers can aid in the detection of radicular symptoms.4
Imaging studies have been investigated as a marker of painful lumbar facet joints. While degenerative changes can be found in imaging, they have not been correlated as a reliable predictor of success with facet interventions.4, 8 Nonetheless, imaging studies often play an important role in the exclusion of other etiologies of back and cervical/thoracic pain. Single-photon emission computed tomography (SPECT), a nuclear medicine imaging technique, can identify active inflammatory markers as seen in facet disease but have not shown consistent results in the prediction of facet joint intervention success. 2020 Consensus Guidelines reported on 12 studies and concluded moderate evidence for SPECT (grade C, moderate certainty) and weak evidence for scintigraphy, MRI, and CT with no to weak supporting evidence.4 2020 ASIPP Guidelines reported level III evidence for SPECT with weak strength of recommendation and level V evidence for other imaging modalities, weak recommendation.8
Conservative treatment, also called medical/interventional treatment, includes integrative treatments (such as acupuncture [see NCD 30.3] or spinal manipulation); physical treatments (physical therapy including exercise, heat and cold modalities, massage), medications (non-steroidal anti-inflammatory drugs [NSAIDS]/antidepressants), and lifestyle modifications (weight loss, sleep hygiene, nutrition, smoking cessation) are typically perused before interventional procedures. Facet joint pain is frequently accompanied by other pain etiologies, which may benefit from conservative modalities or combined therapy, and it is well accepted that some back pain will resolve spontaneously or with conservative or non-invasive measures over time. A few studies had a conservative arm, or investigated combined modalities that support a combined approach, but did not find a conservative approach alone consistently led to improvement.5, 17 The Agency for Healthcare Research released a systematic review (SR) of noninvasive nonpharmacological treatment for chronic pain, including cervical/thoracic and low back. Two-hundred and two trials that evaluated the spectrum of non-invasive treatment modalities concluded durable slight to moderate improvement in function and pain for specific chronic pain conditions and support clinical strategies that focus on non-pharmacological and non-invasive therapies.9,10,18,19 2015 NASS Guidelines recommend a failure of at least 4 weeks of non-invasive care. 6 2020 Consensus Guidelines recommend a 3 month trial of different non-invasive treatment.4 2020 ASIPP Guidelines rated level of evidence II with a strong recommendation for 3 months after onset and failure of conservative management 7; European Guidelines extend the period to 1 year. 7 Chronic pain may lead to stress, anxiety, poor sleep and depression, and other psychological sequelae and treatment beyond the pain symptoms may be necessary.
Optimally a biopsychosocial model that promotes a multi-disciplinary team approach addressing physical pain and psychological factors are utilized. 20 Patients with chronic pain may also benefit from cognitive behavioral therapy, biofeedback, and other psychological interventions. 21
Due to the lack of reliable history, physical exam, or imaging to predict response to facet interventions, diagnostic injections may be given for diagnostic purposes to determine if the facet joint is the source of suspected spinal pain. The response pattern to diagnostic facet joint injections has become the gold standard for diagnosing facet syndrome. Temporary or prolonged abolition of the spinal pain suggests that facet joints were the source of the symptoms.1 The possibility of false-positive and false-negative reporting is an inherent risk with facet blocks and challenges identifying the patients most likely to have a positive response to treatment.4, 8 Intra-articular (IA) and MBBs have been evaluated for predictive value for successful RFA. 2020 ASIPP Guidelines reported on 10 studies in the lumbar spine and found prevalence rates ranged from 27% to 40% with false-positive rates of 27% to 47%, with ≥ 80% pain relief. They conclude level 1-2 evidence with moderate to strong strength of recommendation of lumbar, diagnostic facet nerve blocks. 8 While both IA and MBB blocks have been shown in studies to be predictive of success with RFA (2020 Consensus Guidelines grade B recommendation, low level of certainty) 4 5 studies comparing lumbar MBB to IA injections, including 2 randomized studies1,9 supports MBB as the preferred modality, largely due to high technical failure rate and pain associated with the IA injections. One randomized trial focusing on younger patients shows IA injection with steroids may play a role in patients in which MBB is contraindicated (Grade C evidence, moderate certainty).4 The Greater Manchester EUR Policy Statement on Facet Injections no longer commissioned IA facet injections and recommended medial branches nerve blocks for diagnostic evaluation for RFA. 7 The Spinal Intervention Society (SIS) recommended that medial branch blocks replace intra-articular injections as a diagnostic indicator.1
In order to determine if a block is successful, there must be an assessment/measurement of pain and function. There are three points in which pain/function must be evaluated: 1. baseline; 2. after a diagnostic block; and 3. at each follow-up to evaluate long term relief. The definition of success lacks consistency, and there are different cut off values in the literature. Among the Multi-MAC SME panel, there was an agreement that subjective improvement in pain is a valid measurement of improvement in pain (average voting score of 3.8/5). However, there was not agreement on what the cut-off should be, if a tool should be used, and if so, which tool. There was also a consensus that function is the most important indicator of success. A study assessed the validity of subjective improvement rating improvement after one IA joint injection and compared subjective rating to use of VAS scoring and concluded that validity of pain provocation alone as criterion standards in patients undergoing diagnostic facet injections should be questioned with the positive predictive value of 16% for predicting facet joint as a source of pain.22 Clinical trials and policy have used multiple standardized tools to measure pain, including the NRS and VAS, with pre-set cut off values in an attempt to determine a specific measurement in which patient’s may most benefit from intervention. Studies have evaluated if a specific cut-off value can predict outcomes of RFA and do report a high correlation between verbal rating scales, NRS and VAS scores in prediction of outcomes with RFA. However, the panel did not agree on a minimum value that can be used with these tools. The Multi-MAC SME panel did agree that measurement of function can provide valuable clinical input into improvement, such as the ability to stand, walk, and the ability to do activities of daily living and can predict success with future therapeutic procedures. There are multiple tools to measure function including the PDAS, 23 ODI,24 OSW, QUE,25 Roland Morris Pain Scale, 26 Back Pain Functional Scale (BPFS), 27 and the easy to use PROMIS profile domains which have been found to correlate well with the ODI scale. 28
For the diagnostic block, the pain relief achieved is temporary and used as a predictor of success for subsequent RFA. The objective is to reduce false-positives that would not be predictive of success with RFA and avoid false-negative patients who could benefit but would not be offered treatment. Most studies have used a cut-off of pain relief greater than 80% to consider MBB as positive. Ten studies assessing the prevalence of lumbar facet joint pain using a cut-off value of 80% relief reported a prevalence rate of 27% to 40% with false-positive rates of 27% to 47% receiving a moderate to a strong recommendation from 2020 ASIPP Guidelines.8 One paper reports dual comparative blocks are advocated as a means of identifying true-positive cases and excluding placebo responders and have been shown to have a sensitivity of 100% and a specificity of 65%. 29
As stated in the 2020 Consensus Guideline: “the cut-off designating an MBB as positive is one of the most controversial areas in pain medicine”.4 Cohen et al in 2013, in a prospective study to evaluate predictive values reported no difference in the predictive value of ≥ 50% to <80% pain reduction vs. ≥80% pain reduction.30 The guidelines advocate for using ≥50% for clinical trials and clinical practice. The guidelines acknowledge that the existing evidence does not adequately address the 50-80% group and that this cut-off was selected to maximize access to care given lack of reliable alternative treatment options in this population and potential benefit of treatment in this group.4 On the contrary, there are studies that show patients with ≥80% relief are more likely to show a positive response to RFA. 2020 ASIPP Guidelines report Level I to II evidence based on ten diagnostic accuracy studies (using ≥75% and ≥80% criterion) and offer moderate to strong strength of recommendation. They cite the literature using the 50% cut-off is conflicting due to internal inconsistencies. 8
There is controversy regarding the number of diagnostic blocks needed to ensure an accurate diagnosis before proceeding with RFA. Derby et al evaluated the correlation of lumbar MBB with diagnostic MBB cutoff values to optimize therapeutic outcomes and a failure of single MBB and conclude with a dual block protocol a 70% cut-off value was acceptable. With a single block, 80% or higher was optimal. 31,32 Three SRs also showed significantly better improvement with dual MBB with 80% cut off value. 33-35 Two randomized controlled trials (RCTs) (one in the cervical region) demonstrated positive results with dual blocks.36,37 SIS and ASIPP advocate for dual diagnostic blocks, and diagnostic accuracy is reduced if lower cut-off criteria are used. In contrast, the 2020 Consensus Guidelines advocate for single blocks using a 50% cut-off. One RCT compares outcomes of stratified by different prognostic values and reported the success rate in those who underwent RFA in the zero (no block), single and double block groups were 33%, 39%, and 64%, respectively.38 Another study reporting on success rates of RFA based on the number of blocks concludes no difference in outcomes based on the number of blocks.39 A meta-analysis of 5 RCTs using zero or one block favored RFA.40 However, a meta-analysis is challenging given the high heterogenicity of the literature. The 2020 Consensus Guidelines suggest the number of blocks depends on the goals with dual blocks preferable for research where diagnostic accuracy is critical while single (or no) blocks reduce the number of procedures and access to care. Balancing these factors, they recommend a single block reporting moderate evidence that dual blocks result in higher success with RFA, but zero-block results in the highest number of patients with a positive response to RFA.4 The result of voting from the Multi-MAC SME Panel was a score of 3.2/5, stating confidence in the clinical literature to support two MBB needed to diagnose facet pain. NASS Guidelines recommend dual MBB blocks on 2 separate occasions and second block administered only if >80% relief with the first block due to an unacceptably high false-positive rate of single diagnostic injection.6 In the 2020 NASS Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care, they state a single diagnostic IA injection with 50% pain relief provides no clinically meaningful improvement at 6 months (Grade of Recommendation B) and insufficient evidence to make a recommendation for or against the use of RFA (Grade of Recommendation I [Insufficient]).5
The literature and societal guidance report that diagnostic injections should be medial branch blocks, not intraarticular injections. This is agreed upon in the 2020 Consensus Guidelines, 2020 ASIPP Guidelines, and NASS Guidelines. NASS Guidelines state IA facet injections have not been validated for diagnostic use, and the false positive rate is unknown as well as lack of effectiveness studies comparing IA vs. MBB in the cervical spine.6 There are exceptions in the case of the occipitoatlantal and atlantoaxial joints, since there are no medial branch or other intervention to block readily. In these cases, dual blocks with 80% relief are supported by most guidelines.5
Therapeutic Joint Injections
Intra-articular injections into the facet joint have been used as a treatment modality for facet related pain and remains controversial. Therapeutic injections typically include a corticosteroid as there would not be anticipated long-acting pain relief from a short-term local anesthetic. Among the Multi-MAC SME panel, the average voting was 2.70, with a range from 1-4. There is clinical evidence against the use of IA therapeutic facet joint injection. Lilius et al conducted an RCT including 109 patients who failed to show a difference between saline, steroids, and anesthetic injected around two facet joints.41 Carette et al conducted an RCT including 101 patients with IA lumbar facet pain which showed a non-significant difference between the injection of saline and depo-corticosteroid with 22% in the steroid group compared to 5% in the saline group reporting benefit at 6 months. 42 A small RCT, including 41 patients, reported return of pain in 3 days after IA steroid injection compared to 3.5 days in the control. 43 Kennedy et al performed a small RCT comparing IA facet injections with a steroid to saline and did not find a change in need for RFA. 44 In the FACTS study, a double-blinded RCT, Cohen et al found no significant difference for pain relief or functional outcome change between lumbar facet IA injection with steroid or anesthetic or MBB with steroid, anesthetic or saline for up to 6 months post-injection. Five patients made it to the 6 month follow-up, of which 2 had RFA. The FACTS study also found that MBB for anesthetic or steroids did not perform better than saline. 9
On the contrary, a SR by Manchikanti et al (2014) using a modified approach to the grading of evidence 2 was completed and reported 20 RCTs assessed with moderate to high-quality methodological criteria. For therapeutic interventions, the evidence was variable from level II to III, with level II evidence for lumbar facet joint nerve blocks and radiofrequency neurotomy for long-term improvement (greater than 6 months), and level III evidence for lumbosacral zygapophysial joint injections for short-term improvement only. This review provides evidence for the diagnostic validity of facet joint nerve blocks, and moderate evidence for therapeutic radiofrequency neurotomy and therapeutic facet joint nerve blocks in managing chronic low back pain.16 These 2 studies have been criticized for a high proportion of patients taking opioids and prior back surgery, lack of control groups, and the absence of blinding.4 Schneider et al reported in rigorously selected patients, 56% of patients had 100% pain relief at 6 months.45 A SR by Engel reported sustained relief of 6 months, and 1/3 had relief at 1 year. 34
This is in contrast with another SR during the same period that looked at the evidence supporting the use of therapeutic IA facet joint injections for patients with suspected facet joint pain. The review focused on IA facet joint injections with active drug or placebo/inactive injection are more effective in reducing back pain and back pain-related disability than conservative treatment. A total of 391 records were screened, and 6 trials were included. The trials included were small (range 18 -109 participants), and overall in terms of pain and disability outcomes, most were inconclusive. Only 2 of the trials report any significance between the group’s differences in pain or disability outcomes. The authors addressed the limitations and flaws in these trials that were clinically diverse and precluded any meta-analysis. Several methodological issues were identified. The positive results are interpreted with caution and suggest that there is a need for further high-quality work in this area. 46
Many societal recommendations that do not support the use of therapeutic facet joint injections include:
- The 2020 Consensus Guidelines developed by a multispecialty international working group recommend against the routine use of therapeutic facet injections giving it a grade D, moderate level of certainty.4
- National Institute for Health and Care Excellence (NICE) guideline on Low back pain and sciatica in over 16s: assessment and management10 recommendations are based on SRs of best available evidence and explicit consideration of cost effectiveness. The NICE recommendation for image-guided facet joint injections “Do not offer spinal injections for managing low back pain. The Guideline Development Group (GDG) agreed that health-related quality of life, pain severity, function, and psychological distress were the outcomes that were critical for decision making. Responder criteria (greater than 30% improvement in pain or function), adverse events, and healthcare utilization were also considered as important. Evidence was reported for all the outcomes except for psychological distress and healthcare utilization. For image-guided facet joint injections, evidence was only available for pain, function, and responder criteria. There was no evidence for any of the other outcomes.” The NICE summary concludes: “Overall, the GDG agreed that there was no consistent good quality evidence to recommend the use of spinal injections for the management of low back pain. There was minimal evidence of benefit from injections, and reason to believe that there was a risk of harm, even if rare.
- The GDG consequently agreed that it was appropriate to recommend against the use of spinal injections for people with low back pain.”
- The American Association of Neurological Surgeons (AANS) and the Congress of Neurological Surgeons (CNS) 2014 Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine: Part 13: injection therapies, low-back pain, and lumbar fusion. Lumbar intraarticular facet injections are not recommended for the treatment of chronic lower-back pain. The literature does suggest the use of lumbar medial nerve blocks for short-term relief of facet-mediated chronic lower-back pain without radiculopathy. 11
- The North American Spine Society (NASS) Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care: Diagnosis and Treatment of Degenerative Lumbar Spondylolisthesis 2nd Edition (2016) reports that there is insufficient evidence to make a recommendation for or against the use of injections for the treatment of degenerative lumbar spondylolisthesis. Grade of Recommendation: I (Insufficient Evidence).6 The 2020 NASS Low Back Pain Guidelines state there is insufficient evidence to make a recommendation for or against the use of steroid injections for suspected facet-mediated pain (Grade 1 Recommendation) not sufficient evidence for or against the use of 50% reduction in pain following MBB for diagnosis of facet joint pain (Grade 1 Recommendation). The guidelines also state that the outcomes of RFA become more reliable when more stringent diagnostic criteria are used, and relief is durable for at least 6 months following procedure (Grade B Recommendation).5 NASS Guidelines state while there is some evidence in the literature when compared to RFA, RFA offers longer-term pain relief, and long-term outcomes have not been reported in adequately designed trials. They state that if therapeutic IA injections are used, they should be used in patients whose initial injections resulted in pain relief >50% for at least 3 months and should not be repeated more than 3 times annually. The guidelines address concern of the majority of research on therapeutic MBBs comes from a single-center, reports on prospective studies and one RCT which had unspecified intervals and cannot determine the true duration of treatment and concern with lack of studies comparing therapeutic MBBs to medial branch RFA.5, 6
- Agency for Healthcare Research and Quality (AHRQ) Technology Assessment Program: Pain Management Injection Therapies for Low Back Pain (2015) authors used predefined criteria and selected randomized trials of patients with lumbosacral radiculopathy, spinal stenosis, nonradicular back pain, or chronic postsurgical back pain that compared effectiveness or harms of the epidural, facet joint, or sacroiliac corticosteroid injections versus placebo or other interventions. Also included were randomized trials that compared different injection techniques and large (sample sizes greater than 1,000) observational studies of back injections that reported harms. Seventy-eight randomized trials of epidural injections, 13 trials of facet joint injections, and one trial of sacroiliac injections were included. Limited evidence suggested that epidural corticosteroid injections are not effective for spinal stenosis or nonradicular back pain and that facet joint corticosteroid injections are not effective for presumed facet joint pain.12
- A 2009 American Pain Society guideline recommends against the use of corticosteroids into the facet joint. 21
Some societal recommendations supporting the use of therapeutic facet joint injections include:
- 2020 ASIPP Guidelines 8: Therapeutic Facet Joint Interventions in Lumbar Spine states:
- The level of evidence is II with moderate strength of recommendation for therapeutic lumbar facet joint nerve blocks with the inclusion of 3 relevant randomized controlled trials with long-term improvement.
- The level of evidence is IV with a weak strength of recommendation for lumbar facet joint intraarticular injections with inclusion of 9 relevant randomized controlled trials, with most of them showing lack of effectiveness without the use of local anesthetic.
The American Society of Anesthesiologists (ASA) Task Force on Chronic Pain Management and the American Society of Regional Anesthesia and Pain Medicine (ASRA) Practice Guidelines for Chronic Pain Management (2010) 47:
- Recommendations for joint blocks: RCTs report equivocal findings regarding the efficacy of facet joint steroid injections compared with facet saline injections regarding pain relief for patients with low back pain (LBP). However, studies with observational findings for facet joint injections indicate that pain scores are improved over baseline scores for assessment periods of 1-6 months. Intraarticular facet joint injections may be used for symptomatic relief of facet-mediated pain. Medial branch blocks may be used for the treatment of facet-mediated spine pain.
- The American Association of Neurological Surgeons (AANS) and the CNS 2014 Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 13: injection therapies, low-back pain, and lumbar fusion states lumbar intraarticular facet injections are not recommended for the treatment of chronic lower-back pain. The literature does suggest the use of lumbar medial nerve blocks for short-term relief of facet-mediated chronic lower-back pain without radiculopathy.11
Radiofrequency Ablation
Radiofrequency neurotomy is described as radiofrequency lesioning performed utilizing either a heat lesion or pulsed mode radiofrequency. A thermal radiofrequency neurotomy lesion for facet denervation is performed at 80° to 85°C. Clinically, a higher temperature allows for a larger lesion to be made. The size of the lesion is influenced by the vascularity of the surrounding tissue: the greater the vascularity of the tissue, the smaller the lesion. Overall, the mechanism of radiofrequency neurotomy is described as denaturing of the nerves. Consequently, with radiofrequency, the pain returns when the axons regenerate, requiring repetition of the radiofrequency procedure. The pulsed mode radiofrequency is an application of a strong electric field to the tissue that surrounds the electrode, and the temperature of the tissue surrounding the tip of the electrode does not exceed 42°C and heat is dissipated during the silent period. 8
The effectiveness of radiofrequency ablation to improve pain and function for facet joint mediated back pain in carefully selected individuals has been explored in the medical literature. Clinical trials report conflicting data on the effectiveness of RFA. Most clinical trials defined success with RFA as 50% pain relief at 6 months.
A 2015 Cochrane review by Maas et al, including 23 RCTs (n=1,309), evaluated patients who had a positive response to diagnostic block and underwent RFA found moderate evidence on the effectiveness of RFA compared to placebo for pain management of facet origin over the short term (mean difference [MD] -1.47, 95% confidence interval [CI] -2.28 to -0.67). Low-quality evidence that facet joint RFA is more effective than placebo for function over the short term (MD -5.3, 95% CI -8.66 to -.20) and over the long term (MD -3.9, 95% CI -6.94 to 0.47). Radiofrequency ablation for disc pain did not show effects compared to placebo over the short or long term (MD -1.63, 95% CI -2.58 to -.68). They concluded no high-quality evidence to suggest RFA procedure provides pain relief for patients with chronic low back pain. 48
Juch et al reported on 125 patients in the treatment arm and 126 in the control arm (exercise). Patients had a single diagnostic block with at least 50% or more pain reduction before RFA. The mean difference for the primary outcome pain intensity at 3 months was −0.18 (95% CI, −0.76 to 0.40). The mean difference for functional status at 3 months was −2.45 (95% CI, −5.53 to 1.03); the RR for global perceived recovery at 3 months was 1.35 (95% CI, 0.81 to 2.05). This study has been challenged, stating that the lack of efficacy was due to the treatment arm using the perpendicular technique.49 Perpendicular electrode placement has been questioned with concern it may fail to reach the target nerve or only capture a segment, while parallel electrode placement reliably captures the target nerve and does so along a substantial length of the nerve. Those who challenge these studies report there are 3 studies (1999-2008) that utilized the parallel technique that would result in positive outcomes and report support for RFA from these trials. 49 There are no recent trials that address this controversy.
Leggett et al (2014) conducted a SR to determine the efficacy of RFA for chronic low back pain associated with lumbar facet joints, sacroiliac joints, discogenic low back pain, and the coccyx. Included articles were sham-controlled RCTs, that assessed the efficacy of RFA, reported at least 1 month of follow-up, and included participants who had experienced back pain for at least 3 months. Eleven sham controlled RCTs were included: 3 studies involving discogenic back pain, 6 studies involving lumbar facet joint pain, and 2 studies involving sacroiliac joint pain. No studies were identified assessing the coccyx. The evidence supports RFA as an efficacious treatment for lumbar facet joint and sacroiliac joint pain, with 5 of 6 and both of the RCTs demonstrating statistically significant pain reductions, respectively. The evidence supporting the RFA for the treatment of discogenic pain is mixed. Future studies should examine the clinical significance of the achieved pain reduction and the long-term efficacy of RFA.50
The SR (2014) by Manchikanti et al looking at both therapeutic injections, and RFA in lumbar, cervical and thoracic regions evaluated 21 RCTs and 5 observational trials, using a modified approach to the grading of evidence,3 reported Level II evidence 2 for RFA in the lumbar and cervical spine, and level IV in the thoracic region.33 A SR by Engel et al 2016, which serves as the basis for NASS recommendations, “The Effectiveness and Risks of Fluoroscopically-Guided Cervical Medial Branch Thermal Radiofrequency Neurotomy: A Systematic Reviews with Comprehensive Analysis of the Published Data” using the GRADE system for rating. They conclude the majority of patients were pain-free at 6 months and over a third pain-free at 1 year.34 In 2017, Lee et al conducted a meta-analysis that included 7 trials with 454 patients comparing RFA (n=231) to sham or epidural (n=223) and reported greater improvement in the RFA group.40
2020 ASIPP consensus guidelines 7 reports on 11 studies on RFA effectiveness and concludes:
- Lumbar Spine: The level of evidence is II with moderate strength of recommendation for lumbar radiofrequency ablation with the inclusion of 11 relevant RCTs with 2 negative studies and 4 studies with long-term improvement.
The American Society of Anesthesiologists (ASA) Task Force on Chronic Pain Management and the ASRA Practice Guidelines for Chronic Pain Management (2010) Recommendations for Ablative Techniques (ASA 2010) 47: The Task Force notes that other treatment modalities should be attempted before consideration of the use of ablative techniques.
- Chemical denervation: Chemical denervation (e.g., alcohol, phenol, or high-concentration local anesthetics) should not be used in the routine care of patients with chronic non-cancer pain.
- Cryoablation: Cryoablation may be used in the care of selected patients (e.g., post-thoracotomy pain syndrome, low back pain [medial branch], and peripheral nerve pain).
- Radiofrequency ablation: Conventional (e.g., 80°C) or thermal (e.g., 67°C) radiofrequency ablation of the medial branch nerves to the facet joint should be performed for low back (medial branch) pain when previous diagnostic or therapeutic injections of the joint or medial branch nerve have provided temporary relief. Conventional radiofrequency ablation may be performed for neck pain. Conventional or thermal radiofrequency ablation of the dorsal root ganglion should not be routinely used for the treatment of lumbar radicular pain.
National Institute for Health and Care Excellence (NICE) guideline on Low back pain and sciatica in over 16s: assessment and management (2017) Evidence Statement 51:
- Radiofrequency denervation compared with placebo/sham for low back pain: Evidence from 4 studies demonstrated clinical benefit in pain for radiofrequency denervation compared to placebo/sham at both the short and long-term follow-ups of less than and greater than 4 months (low to moderate quality, n=160). In contrast, there was no difference in function between treatments at any time point. Conflicting evidence from one study for quality of life at less than 4 months follow-up showed clinical benefit for radiofrequency denervation compared to placebo/sham for the SF-36 domains of general health and vitality. Radiofrequency denervation was inferior to sham for the domains of mental health, pain, and social function. There was no difference between treatments for the physical domain (low quality, n= 81).
Evidence from a single study reporting adverse events at less than 4 months follow-up demonstrated an increase in adverse effects for radiofrequency denervation in terms of the number of patients with moderate or severe treatment-related pain (low quality, n = 79). There was no difference in other adverse events (change of sensibility and loss of motor function) at short term follow-up when radiofrequency denervation was compared to placebo/sham in the same study (very low quality).
Additionally, when compared with placebo/sham, a benefit for radiofrequency denervation in responders to pain reduction measured by global perceived effect was demonstrated by 2 studies at both the less than and greater than 4 months follow-up time points. However, this was not seen for pain reduction measured by VAS at less than 4 months reported by a single study (low quality, n equal to 111).
- Radiofrequency denervation versus medial branch block:
Evidence from a single study demonstrated clinical benefit in terms of pain for radiofrequency denervation compared to medial branch blocks at both the short- and long-term follow-ups of less than and greater than 4 months (very low quality, n = 100). Radiofrequency denervation has evolved as a treatment for spinal pain over the last 40 years and is a minimally invasive and percutaneous procedure performed under local anesthesia or light intravenous sedation. Radiofrequency energy is delivered along an insulated needle in contact with the target nerves. This focused electrical energy heats and denatures the nerve. This process may allow axons to regenerate with time, requiring the repetition of the radiofrequency procedure.
- The duration of pain relief following radiofrequency denervation is uncertain. Data from randomized controlled trials suggests relief is maintained for at least 6-12 months, but no study has reported longer-term outcomes. Pain relief for more than 2 years would not be an unreasonable clinical expectation.
- The de novo economic model undertaken for this guideline for radiofrequency denervation suggested that the treatment is likely to be cost-effective, provided the duration of effect exceeds 16 months.
- If radiofrequency denervation is repeated, we do not know whether the outcomes and duration of these outcomes are like the initial treatment. If repeated radiofrequency denervation is to be offered, we need to be more certain that this intervention is both effective and cost effective.
NASS Guidelines state that therapeutic medial branch RFA is a validated treatment for facet mediated pain, and repeat procedures are equally successful if the response to the initial RFA lasted at least 3 months. These guidelines advocate dual diagnostic MBB with ≥80% relief of the primary (index pain), and the onset, and minimum duration of relief is consistent with the agent employed. Also, RFA should be performed at the same level no more than twice annually, and only if the initial radiofrequency lesion results in significant pain relief (> 50%) for at least 6 months. In those situations, a repeat procedure in that year is appropriate. 52 2020 NASS Low Back Pain Guidelines states there is insufficient evidence to make recommendations for or against the use of cryodenervation for treatment of zygapophyseal (facet) joint pain.5
The American Association of Neurological Surgeons (AANS) and the CNS 2014 Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 13: injection therapies, low-back pain, and lumbar fusion. Lumbar intraarticular facet injections are not recommended for the treatment of chronic lower-back pain. The literature does suggest the use of lumbar medial nerve blocks for short-term relief of facet-mediated chronic lower-back pain without radiculopathy. Lumbar medial nerve ablation is suggested for 3-6 months of relief for chronic lower-back pain without radiculopathy. Diagnostic medial nerve blocks by the double-injection technique with an 80% improvement threshold are an option to predict a favorable response to medial nerve ablation for facet-mediated chronic lower-back pain without radiculopathy. Still there is no evidence to support the use of diagnostic medial nerve blocks to predict the outcomes in these same patients with lumbar fusion.11
Cervical and Thoracic Spine
Most of the literature focuses on the lumbar region regarding interventional facet joint diagnosis, and the 2020 Consensus Guidelines are specific for the lumbar region. The 2020 ASIPP Guidelines include the cervical and thoracic regions. The 2020 ASIPP Guidelines report level I-II with moderate to strong strength of recommendation for lumbar, diagnostic blocks report 10 diagnostic accuracy studies to support the recommendation. ASIPP report level II evidence for the cervical spine with moderate strength or recommendation citing 10 diagnostic accuracy studies. Two SRs support reliance on dual diagnostic blocks with 100% relief of the index pain to select patients for the procedure reporting more than 60% selected using this stringent criterion had 100% relief of index pain. They were pain-free at 6 months and nearly 40% pain free at 1 year with functional improvement in neck pain. 34,35
ASIPP (2020) 8 Therapeutic Facet Joint Intervention Cervical Spine:
- The level of evidence is II with moderate strength of recommendation for therapeutic cervical facet joint nerve blocks with the inclusion of 1 relevant randomized controlled trial and 3 observational studies, with long-term improvement.
- The level of evidence is V with weak strength of recommendation for cervical intraarticular facet joint injections with the inclusion of 3 relevant randomized controlled trials, with 2 observational studies, the majority showing lack of effectiveness. In contrast, 1 study with a 6 month follow-up showed a lack of long-term improvement.
- The level of evidence is II with moderate strength of recommendation for cervical radiofrequency ablation with the inclusion of 1 randomized controlled trial with positive results and 2 observational studies with long-term improvement.
Evidence to support use in the thoracic region is further supported by one 2012 SR reporting evidence for diagnostic accuracy of the thoracic facet joint injection, and one 2018 study comparing thoracic IA vs. MBB reporting significant pain relief with thoracic joint injection. 53,54 NASS guidelines state the lack of supporting literature for the use of IA injections for thoracic pain, however, states the lack of other effective alternative therapies.6
Imaging
Image guidance has become standard care for facet blocks and RFA procedures, allowing accurate needle placement, monitor contrast and anesthetic spread, and improved safety by direct visualization of bony elements and avoiding surrounding structure. Studies dating back to the 1980s comparing “blind” injections to image-guided concluded that the procedure should not be performed without radiographical imaging. Fluoroscopy is considered the gold standard for facet block procedures, and most studies were conducted with fluoroscopic guidance consistent with societal recommendations. The U.S. Department of Health and Human Services OIG report in 2008 asserted radiographic guidance is recommended. 55 One cadaveric study showed improved accuracy with fluoroscopy over CT. 56 2020 Consensus Guidelines recommend CT or preferably fluoroscopy for lumbar MBB (grade B recommendation), CT scanning for IA placement (grade C recommendation), and fluoroscopy for medial branch RFA (grade B recommendation, low level of evidence). The Guidelines state fluoroscopy is preferred to CT due to lower cost, faster times, and less radiation exposure than CT.4
The use of ultrasound has been explored as an alternative imaging modality. Cadaveric, retrospective studies, and reviews of RCTs and non-RCTs suggest that there is little difference between ultrasound and fluoroscopy guided procedures; however, there are no well-designed studies to report the safety of this approach. Limitations for ultrasound guidance include reduced visibility in obese patients, more challenging to target the proper segment, and not being able to visualize facet joint.4 The NASS Guidelines state insufficient evidence to support use of ultrasound guidance.11 Subject matter experts score low confidence that the facet joint procedures can be performed under ultrasound guidance (score 1.7/5).
Facet Joint Cyst Rupture
Facet joint cysts have been found to have a prevalence of 6.5% and are thought to play a role in facet mediated pain. In these cases, nerve root compression or irritation is associated with radicular pain like other neuro-compressive lesions. Rupture of the cysts have been associated with pain improvement and may potentially avoid more invasive open surgical procedures. In these cases, IA injection is used and often with TFESI to treat radicular pain. 6 A SR of 870 patients report cyst resolution to be 58% for the percutaneous procedure, and 90% for decompressive procedures concluding advantage of surgical intervention as compared to percutaneous procedures and pain relief with surgical management is estimated 83.5%. Shuang et al SR of 29 studies reported overall the satisfactory results (after short- or long-term follow-up) were achieved in 55.8% [49.5, 62.08] (pooled mean and 95% CI) of the 544 patients subjected to percutaneous lumbar facet joint cyst resolution procedures. 38.67% [33.3, 43.95] of this population underwent surgery subsequently to achieve durable relief. 57 However, the analysis consisted largely of small retrospective studies and case reports with low-quality evidence. In 1 prospective, non-randomized study, 120 patient’s satisfaction was reported as 75%, with 25% requiring repeat surgery. 58 NASS Guidelines address the concern of cyst reoccurrence, which occurs about 50% of the time and does not recommend repeating the procedure more than once and only if the first procedure produces satisfactory results, which they define as 50% improvement for at least 3 months.6 The subject matter expert panel voted 3.9/5 in support of facet joint cyst rupture for pain relief.
Centralized Pain Syndrome
Facet procedures by nature treat a local pain condition, while a centralized pain syndrome, such as fibromyalgia, is a generalized pain condition. Patients with centralized pain syndromes are thought to have alterations in central neurotransmission. A prospective study with 548 patients diagnosed with primary spine pain was also evaluated for fibromyalgia criteria before spinal interventions. 42% of the patients meet diagnostic criteria for fibromyalgia. They determined a profound phenotypic difference in those with fibromyalgia as compared to those with spinal pain alone associated with more neuropathic pain descriptors, anxiety, greater pain interference and lower physical function.
The authors concluded that the phenotypical factors found in the fibromyalgia group may be predictive of poor outcomes in spine intervention procedures.14 Exploration of factors associated with poor outcomes from lumbar RFA and long duration pain was correlated with treatment failure. There is insufficient literature that addresses if facet joint procedures are beneficial for centralized pain conditions.
Intrafacet Implants
Intrafacet implants have been proposed as an alternative technique to surgical fusion. They involve the placement of an allograft dowel made from bone (from femur or tibia) and placed surgically or via the minimally invasive procedure. The allografts, which are processed by licensed tissue banks, which must be compliant with FDA requirements for tissue processing, are not subject to FDA 510K clearance and can be marketed. There are no clinical trials that address the efficacy and safety of these implants. The report on 6 cases did not indicate efficacy.15
Nonthermal modalities
Several alternatives to percutaneous radiofrequency denervation have been proposed, including pulsed radiofrequency, cryoablation, laser ablation, and chemical ablation, in which a neurolytic substance (e.g., alcohol, phenol, glycerol) is injected into the affected nerve root. An alternative method of denervation using an endoscopic approach (i.e., endoscopic dorsal ramus rhizotomy) has also been proposed. 59 The literature on these modalities is largely limited to case reports or small series with mixed results. 52,60-62 One RCT (n=80) comparing pulsed radiofrequency ablation to steroid injections concluded it may be more effective than steroids.63 A RCT (n=50) compared study of continuous to pulsed radiofrequency ablation and did not report significant differences. 64 Long term safety and efficacy data is lacking. The American Society of Anesthesiologists (ASA) Task Force on Chronic Pain Management and the ASRA Practice Guidelines for Chronic Pain Management (2010) Recommendations for Ablative Techniques: The Task Force notes that other treatment modalities should be attempted before consideration of the use of ablative techniques. 47
Anesthesia
The American Society of Anesthesiologists provides definitions on the continuum of the depth of sedation. Minimal sedation anxiolysis is defined as a drug-induced state during which patients respond normally to verbal commands. Although cognitive function and physical coordination may be impaired, airway reflexes, and ventilatory and cardiovascular functions are unaffected. Progressing depth of sedation beyond minimal is moderate or “conscious”, deep and general. Monitored Anesthesia Care or “MAC” is not a depth of sedation, but a specific anesthetic service allowing a deeper level of analgesia than can be provided by moderate sedation. Statement on Continuum of Depth of Sedation: Definition of General Anesthesia and Levels of Sedation/Analgesia.65
The increased risk associated with the use of anesthesia, including sedation, in the elderly population must be considered. A 2020 review reports a substantial increase in the use of non-operating room anesthesia (NORA) for elderly patients and that advanced age is an independent risk factor for anesthesia-related adverse events in this population. The authors explain there are significant changes in pharmacological effects of anesthetic agents with aging requiring reduced dosing and careful titration and monitoring to reduce adverse events. They also report that increasing age increases the risk of aspiration and cognitive complications even during sedation. The paper discusses that older and frailer patients may benefit greatly from less invasive procedures, but this must be balanced against safety outside of a high acuity operating suite and increased risk associated with anesthetic in this population.66 "Nonoperating room anaesthesia for elderly patients." A retrospective analysis from the 2008-2012 Premier Database reviewed 21,276,691 inpatient discharges seeking a better understanding of the risk of cardiopulmonary resuscitation (CPRA). They found 96,554 patients suffered CPRA and reported patients who received opioids and sedatives had an adjusted odds ratio for CPRA of 3.47 (95% CI: 3.40– 3.54; p<0.0001) compared with patients not receiving opioids or sedatives. Therefore, opioids alone and sedatives alone were associated with a 1.81-fold and a 1.82-fold (p<0.0001 for both) increase in the odds of CPRA, respectively. They found 42% survived CPRA and only 22% were discharged to home calling for further research in this area and efforts to investigate opioid sparing anesthesia and reduced sedative use and improved monitoring given this risk. 67
The American Society of Anesthesiologist committee opinion for anesthetic care during interventional pain procedures for adults stating that when sedation is provided during the performance of pain procedures it is important that the patient can be responsive during critical portions of the procedure to report potential procedure related paresthesia, acute changes in pain intensity or function for potential toxicity. The committee opinion states that interventional pain procedures generally only require local anesthetic however patients may elect to also receive supplemental sedation but must remain conscious. Exceptions may include a well-documented history of inability to cooperate, medical conditions that would prohibit performance of the procedure, or inability to remain motionless.13
The Spine Intervention Society Factfinder for patients states that sedation is not intrinsically necessary for interventional spine procedures and that the decision should be considered on case-by-case basis.68 This report focused on moderate sedation and expresses concern of over-sedation impairing the ability “of the patients to respond adequately to any potential pain, discomfort, or paresthesia during a procedure and warn the physician accordingly of a potential impending serious complication”. The use of heavy sedation has been associated with increased risk of neurological injuries, such as spinal cord injury. Moderate sedation has been associated with apnea and hypoxemia. While some report common use of sedation there is limited evidence of isolated situations where sedation may provide medical benefit. A RCT with 73 subjects with crossover design reported sedation did not predict satisfaction with care or improved pain.69 A report of 6,897 patients with transforaminal epidural steroid injections without sedation reported only a 3% dissatisfaction rate.70
The reports concluded the default use of sedation is not associated with clear health/outcome benefits and is associated with rare but serious increased risk. Most patients are satisfied with care when receiving injections without sedation and it should be used judiciously and under circumstances with careful monitoring and administered by trained providers and with appropriate monitoring.
Reconsideration Request
A reconsideration request was received requesting therapeutic facet joint injections be considered as a first line treatment option for facet pain and include both intraarticular injections or medial branch blocks. Most of the submitted literature was already in the evidence section of the LCD. Additional submitted studies published prior to 2016 were not cited individually in the LCD and many were included in at least one of the SRs that were evaluated in the LCD.33,46
Literature evaluated with this request include:
- A 2022 retrospective report comparing 99 patients who received lumbar facet joint nerve blocks compared to 227 receiving radiofrequency neurotomy with 1 year follow up. Pain improvement was reported in both groups with 100%, 99% and 79% reporting improvement in the nerve block group as compared to 100%, 74% and 65% in the RFA group at 3, 6 and 12 months respectively. Patients received between 1 to 4 nerve blocks and 1 to 2 RFAs. The authors conclude that the outcome from therapeutic facet joint nerve blocks is comparable to RFA. Missing data with 48 of the original 99 and 148 of the original 227 reported at 12 months data limits this data set.71,72 A similar study was conducted to evaluate 132 patients who received cervical medial branch blocks and 163 patients receiving cervical RFA. Of the original group 107 in the injection group and 105 in the RFA group completed 12 month follow up and reported 100%, 94%, and 81% of the patients in the medial branch blocks group, and 100%, 69%, and 64% in the radiofrequency neurotomy group at 3-, 6-, and 12-month follow-up, respectively. Both studies are limited by the retrospective design and without a control group cannot determine if the procedures are equivalent.71, 72
- A European SR explores the management of facet joint osteoarthritis with medial branch blocks. Eight articles were included in the review. The studies were challenged by small sample sizes ranging from 8 to 60 and the majority having less than 30 subjects, short term follow-up with a maximum of 6 months, significant variability in treatments, different tools to measure pain and other limitations leading the authors to conclude that the role of facet injection in the management of low back pain has a positive trend but is non-conclusive.73
- A small RCT compared 60 subjects with a single positive diagnostic block receiving 1-2 level treatment with IA injection or RFA for six months. They reported a decrease in NRS score at 2 weeks, and 1,3, and 6 months for both groups. They report similar outcomes at 6 months for both groups. The authors reported steroid related side effects in the injection group and no adverse events in the RFA group suggesting that the RFA may be a better option for management to reduce the potential adverse events related to steroids.74
- A small RCT with 40 subjects randomized patients with cervical facet joint pain to IA injection or RFA. They report both groups had a decrease in NRS at 1, 3 and 6 months (p=0.000). They report both groups reported ≥50% and the author concludes that RFA is an effective treatment for cervical facet pain while avoiding the adverse effects of steroids.75
- A small prospective study administered a sham block followed by MBB with presumed facet mediated pain to 104 subjects. Patients who experienced improvement with the saline solution were excluded from the study for presumed placebo effect (16.7%) and patients who did not experience at least 50% improvement after the lidocaine injection were referred for evaluation for other potential etiologies (31.7%). The remaining 54 patients were followed with VAS score measurements and 67% reported improvement maintained at 3 months. The remaining 33% reported worsening pain scores over this duration. The authors concluded that this group was the true facet mediated pain while the group that experienced improvement after a single diagnostic medial branch block had myofascial pain which resolved during this 3 month follow up. This is consistent with data that suggests a high false positive rate with a single medial branch block and supports the use of dual diagnostic blocks and encourages a three month follow-up injections to ensure correct diagnosis.76
The new evidence to support the role of therapeutic injections as first line therapy was very low quality. Additional literature supports the coverage position of RFA if dual diagnostics blocks are positive for facet mediated pain. Therefore, there was not sufficient evidence submitted with this reconsideration to change the policy’s coverage position.
Summary of Evidence Submitted During the Comment Period (February 15, 2024 – March 30, 2024)
A 2023 SR and meta-analysis compiles 11 studies (3 RCT, 8 observational) on MBB and RFA for thoracic pain. The authors acknowledge the paucity of high-quality literature and conclude Level II evidence for MBB and Level III evidence for RFA for long term management of chronic thoracic pain.77 Like the above SR the GRADE recommendations are limited by the use of risk of bias tool unique to interventional pain.
A 2023 RCT compared IA to MBB for facet injections for 60 patients with lumbar facet joint pain. Thirty patients received IA blocks vs 30 patients with MBB, and it was found there was statistically significant improvement (p>0.05) in both groups.78 The authors conclude both modalities are safe and effective for administering facet injections. Another 2023 RCT includes 60 patients with chronic facet pain and were randomized to MBB with lidocaine (n=31) or bupivacaine (n=31) and found no difference between the groups for 16 weeks.79 Both studies were limited by small and short-term follow-up.
A 2024 SR was conducted to evaluate the effectiveness of facet nerve blocks as a therapeutic modality for facet joint pain. Risk of bias assessment was assessed with the Interventional Pain Management Techniques – Quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB) for randomized therapeutic trials, and the Interventional Pain Management Techniques – Quality Appraisal of Reliability and Risk of Bias Assessment for Nonrandomized Studies (IPM-QRBNR) for nonrandomized studies.80 Recommendations were developed with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) assessment criteria. They found only 3 of 21 studies showed high level of evidence and 11 studies with moderate level of evidence concluding Level II Evidence to support therapeutic joint nerve blocks for facet mediated spinal pain. The GRADE conclusion is limited by risk of bias assessment being conducted with a tool unique to interventional pain management rather than the risk of bias tools typically used as part of the GRADE analysis.