Radiofrequency ablation for headache pain: an updated systematic review

Introduction

Background

Headache is a symptom of multiple pathologies that has been experienced by most people (1). In many cases, headaches can be benign and are not caused by a significant pathology, leading to very little interruption to quality of life and productivity. However, in the case of recurrent headache, individuals and society can experience significant repercussions (2). A multination study used a cross-sectional survey to estimate direct and indirect costs of headache; they predicted the cost of headaches to be well over 100 billion dollars annually with the vast majority of those costs being caused by indirect costs as defined as loss of productivity and work absenteeism (3).

Headaches can stem from a variety of serious conditions and are divided into two classification groups, including primary and secondary headaches. The three most common primary headaches are tension, migraine, and cluster (4). Primary headaches can be quite debilitating as patients can experience significant nausea, photophobia, pulsating pain, and headache that increases with any type of movement. In terms of secondary headaches, the etiology can be a result of serious diseases that require close management. This can include head or neck trauma, cranial vascular disease, substance use or withdrawal, infection such as meningitis, and psychiatric disorders. It is important for clinicians to be able to identify serious, life-threatening signs of secondary headaches. For example, new onset of severe headache may be a diagnosis of intracranial hemorrhage. Therefore, if a patient is presenting with a worsening headache pattern, focal neurological deficits, or systemic illness, the patient should be worked up for serious etiology (5).

Treatment for headache varies according to headache type. As with most ailments, primary headaches are initially treated conservatively—with lifestyle modification and over the counter medication. In the case of migraines and cluster headaches, both abortive and preventative prescription medications may also be employed (4). Other noninvasive procedures such as botulinum toxin may also be considered for treatment of refractory headache (6).

Rationale and knowledge gap

The above treatment strategies may offer some patients functional recovery but require either scheduled medication adherence or frequent in person visits. Radiofrequency ablation (RFA) is a possible longer term—and potentially permanent—treatment for chronic headache. RFA has been in use for facet joint pain since 1971 after it was first used for lumbar facet pain by Norman Shealy (7). The procedure has been adapted for various uses and typically is applied continuously or pulsed. Continuous RFA is administered using high-frequency current to induce necrosis of the targeted tissue. In contrast, pulsed radiofrequency (PRF) is administered using short high voltage burst currents, which has been observed to cause less complications (8). Both techniques are now being studied for the treatment of multiple headache syndromes.

Objective

Previous studies have addressed the use of RFA and PRF for the management of chronic headache. The aim of this review was to identify the evidence in terms of efficacy and outcomes in the management of headache pain. We present this article in accordance with the PRISMA reporting checklist (available at https://apm.amegroups.com/article/view/10.21037/apm-23-528/rc).

Methods

Search strategy

The authors conducted a literature search through PubMed, MEDLINE, and the Cochrane Databases identifying all potentially relevant published articles until the date June 15th, 2023. The following MeSH terms were searched: “headache” and “radiofrequency ablation”, “radiofrequency ablation”, “radio-frequency”, “RF”, “RFA”, “radiofrequency lesioning”, “ablation”, “neurolysis”, “radiofrequency” therapy”, and “pain”, “analgesia”.

Inclusion criteria

The inclusion criteria included adults with chronic headache lasting at least one month, RFA-related technology (continuous or pulsed), and original studies. Review articles that were identified were reviewed for additional sources. Studies utilizing the visual analog scale (VAS) or numeric rating scale (NRS) pain scores were included in the analysis, if papers did not assess the pain scores then the paper was analyzed further in the discussion. Furthermore, functional, physical disability, and patient satisfaction scores were analyzed if present. If use of medical analgesic therapy was assessed in an article, it was also added to the results of this review.

Exclusion criteria

Papers were excluded if they were animal studies, non-English, non-RFA technologies, non-headache pain related, if the targeted nerve was not relevant to treat headache, and if the research was only available in poster or abstract form.

Quality of assessment of studies

Study quality and eligibility was determined by two researchers. In the case of different opinions regarding article relevance, all authors reviewed and reached a consensus. The information extracted includes the following: publication year, author’s last name, clinical diagnosis, study design, sample size, ablation technique used, RFA settings utilized (temperature and duration) if available, mean pain improvement, mean duration of improvement, side effects, secondary outcome if analyzed, and significant conclusions. The articles were additionally assessed through quality through the risk of bias in non-randomized studies of interventions tool (ROBINS) (Figure 1) and risk of bias visualization tool (ROBVIS) (Figure 2) (9).

Figure 1 Traffic plot detailing risk of bias in non-randomized studies (ROBINS-I).

Figure 2 Traffic light plots of the risk of bias assessment of the RCT studies (ROBVIS). RCT, randomized controlled trial.

Results

Through the search strategy, 580 studies were initially identified: 330 in PubMed, 154 in MEDLINE, and 82 in the Cochrane Database. Fourteen studies were found in the references of relevant articles found through the search. The PRISMA flow diagram is shown in Figure 3. Non-English and articles with animal studies were excluded. Based on initial screening through title and abstract, 465 articles were excluded. A total of 32 full-text articles were included as they met the inclusion criteria of the study (Table 1).

Figure 3 PRISMA flow diagram showing literature search.

Characteristics of the studies and quality assessment

The studies included with their characteristics are shown in Table 1. The studies compared included 13 retrospective studies, 9 prospective studies, 3 case series, 2 case reports, and 5 randomized control studies. Many of the included studies were retrospective studies. The sample sizes for quantitative studies ranged from 1 to 211 (10-12). Study quality ranged from low risk of bias to serious risk of bias. Most studies focused on chronic headache pain for at least 2 years (10,11,13-31). There were 10 studies from the United States (10-12,18,29,32-36). The remaining 22 studies were from other countries (13-17,19-28,30,31,37-41).

Evidence associated with the use of RFA in treatment of headache

Targeted nerves

Eleven of the 32 studies targeted the sphenopalatine ganglion (SPG) (14-16,18,19,21,22,24,31,36,37). Seven studies targeted medial branches of the cervical facet joints (10,13,20,23,27,28,41). Six studies targeted a combination of nerves (12,30,32-35,39). Three studies targeted the greater occipital nerve (25,29,38). Three studies targeted the C2 dorsal root ganglion (DRG) (11,26,40). The remaining study targeted the C2 cervical nerve root (17).

Pain scores

Ten of the 32 studies collected pain scores of the patients at various time points to assess RFA treatment outcomes (10,13,15,17,20,23,26,28,39,41).

Duration of analgesia

Short-term and long-term relief was documented in all 32 studies. Three of the 32 studies found RFA provided short-term pain relief (10,27,30). Twenty-four of the 32 studies found RFA provided more long-term relief including relief up to four months (39), five months (21), six months (12,18,20,29,33,35,37), eight months (11), nine months (19,22,38), and almost one year or more (13-16,25,26,32,34,36,41). The remaining five studies demonstrated both short-term and long-term relief from RFA (23,24,28,31,40).

Functional outcomes

Eleven of the 32 studies investigated functional outcomes after RFA treatment. Four of these studies investigated headache frequency or burden (28,30,32,41). Two studies examined headache duration changes (20,29). The remaining studies used functional measurements including the neck disability index (NDI) (10), Pittsburgh sleep quality index (PSQI) (15), pain disability index (PDI) (36), and the ability to work (26,39).

Patient satisfaction levels

Three of the 32 studies reported on patient satisfaction levels (29,34,35). In each study, patients were assessed whether they would undergo treatment again.

RFA administration technique

One of the 32 studies directly compared RFA versus PRF on the SPG as a cause of headache pain (21). In the study, the mean effectiveness period was reported.

Discussion

This review sought to investigate and characterize the outcomes of RFA on patients with chronic headache pain. We found 32 studies that suggest that RFA can reduce pain scores, provide lasting pain relief, increase function, and increase patient satisfaction. Nearly all studies had a reduction in pain reflecting short-term and long-term improvement of pain relief. Similarly, several studies showed improvement of disability scores or functional scores of patients after RFA. Lastly, a few of these studies examined patient satisfaction of RFA treatment suggesting that RFA was associated with high levels of satisfaction.

Targeted nerves

The majority of the 32 studies solely targeted the SPG suggesting that this nerve can be targeted for chronic headache pain (14-16,18,19,21,22,24,31,36,37). The remaining studies targeted various nerves or areas suggesting that there is not one consistent target for ablation for chronic headache pain. Previous studies have found occipital nerves and pericranial nerves as optimal targets for RFA (12,42,43).

Pain relief scores

About a third of the studies collected pain scores through the VAS of the patients at various time points to assess RFA treatment outcomes (10,13,15,17,20,23,26,28,39,41). All these studies found a reduction in VAS scores suggesting that RFA for chronic headache reduces overall pain scores from baseline. For instance, Yang et al. and Haspeslagh et al. conducted randomized controlled trial (RCT) studies and found that VAS scores improved at the time of follow-up, respectively (20,28). Specifically, Yang et al. found VAS scores were decreased by 2.52 points in the treatment group compared to 0.55 points (P<0.001). Studies that targeted various cervical joints including C1–C2 (10,23) and cervical medial branches (13,39) demonstrated a similar reduction in VAS scores suggesting various RFA targets can reduce pain scores. Odonkor et al. found a VAS score improvement from 9 to 7 (10). Halim et al. reported an average VAS score of 8.5 and responders had more than 50% pain relief (23). Park et al. found VAS scores decreased from baseline of 6.2 to post ablation 1.54 (13). Lastly, Lang et al. reported 70% improvement in pain relief, with VAS improvement 1 day post procedure (39). PRF of the C2 DRG was also shown to reduce VAS scores at 12 months (41) and 2 years (26). Lastly, VAS scores were reduced through ablation of the SPG (15) and C3 cervical root (17) suggesting that higher cervical targets can provide headache pain relief. Xin et al. found that VAS scores decreased from a range of 2–6 before treatment to 1–2 following treatment with RFA of the SPG (15). Wu et al. found that VAS scores reduced from 7.38±1.13 to 2.96±0.96 and 3.08±1.38 at 12 weeks and 24 weeks, respectively (17).

Duration of analgesia

In terms of pain relief, short-term relief is defined as up to three months whereas long-term relief is defined as beyond three months (44). All studies documented duration of pain relief through follow-up. Few studies documented short-term relief (10,27,30), most studies documented long-term relief (11-16,18-22,25,26,29,32-39,41), and several studies documented both short-term and long-term relief (23,24,28,31,40).

In terms of short-term relief, Odonkor et al. found that after RFA of the C1-C2 medial branch nerve, the patient had relief of at least three months (10). Likewise, Stovner et al. performed an RCT and found that RFA of medial branch nerves from C2-C6 on the ipsilateral side of pain, most patients had response in the first three months (27). Kelderman et al. performed a retrospective study in which PRF of the nerve root or ganglion of C1–C2 gave short-term pain relief (30). These outcomes suggest ablation of higher medial branches and nerve roots can deliver short-term pain relief.

Many studies found RFA provided long-term pain relief ranging from four months (39) to over one year (13-16,25,26,32,34,36,41). Lang et al. performed a prospective observational study in which RFA was conducted on the occipital nerve and medial branches of C3 and C4. The authors found that patients had an average relief of about four months (39). Salgado-López et al. performed a similar designed study of PRF and RFA on the SPG. The authors found a mean relief of about five months (21). In the studies that found pain relief up to six months, various nerves were targeted including cervical medial branches, SPG, greater occipital nerves with either RFA and PRF suggesting that targeted nerve and technique do not correlate with duration of relief (12,18,20,29,33,35,37). Fadayomi et al. performed a case report of PRF on the C2 DRG of a patient and found pain relief up to eight months (11). Several studies measured pain relief up to nine months (19,22,38) and up to one year or more (13-16,25,26,32,34,36,41). These studies similarly did not have one common target or technique suggesting that RFA and PRF is effective for pain relief but there is not a superior method.

The remaining studies demonstrated both short-term and long-term relief from RFA suggesting that ablation for chronic headache pain can deliver both short-term and long-term pain relief (23,24,28,31,40).

Functional status

Functional status was assessed in most studies through headache frequency or burden (28,30,32,41), headache duration changes (20), functional measurements such as the NDI (10), PSQI (15), PDI (36), and the ability to work (26,39). In terms of headache frequency, several studies demonstrated a decrease in headache days from baseline suggesting more pain free days for activities of daily living (28-30,32,41). Yang et al. similarly found in a group of 40 participants comparing sham treatment and PRF, headache duration days significantly decreased (20). Odonkor et al. found NDI decreased from 10% from baseline after RFA treatment of the C1-C2 facet joint (10). Xin et al. performed a retrospective study on 24 patients to evaluate CT-guided RFA on the SPG and found that the quality of sleep (PSQI) scores decreased in both migraine and cluster headache patients (15). Narouze et al. performed a retrospective study on 15 patients who had RFA on SPG and found that PDI significantly improved at 6 and 12 months (36). Function was also assessed through ability to work as participants reported an increased ability to work at follow-up (26,39).

Patient satisfaction

Chronic headache pain can highly impact one’s quality of life (45). Patient satisfaction was observed in several studies and reported through various scales (29,34,35). Cohen et al. performed an RCT with 81 participants to compare steroid injections with PRF. The authors used the Likert scale to compare treatments and measure patient satisfaction. Although there was no significant difference between groups, patient satisfaction did increase in the PRF group, suggesting that patients were satisfied at the end of treatment (29). Similarly, Hamer et al. performed a single center retrospective study of 40 participants to evaluate RFA of the C2 DRG and/or third occipital nerves. The authors reported that 92.5% of patients would repeat the procedure if his or her severe symptoms recurred suggesting patients were highly satisfied with results (35). Lastly, Beams et al. described a series of four patients with indomethacin-responsive hemicrania who underwent RFA of the C2 ventral ramus, C2 DRG, or SPG. All patients stated they would repeat RFA treatment as they had a significant headache response (34).

RFA administration technique

Chronic headache pain can be treated with RFA or PRF. Salgado-López et al. directly compared RFA versus PRF on the SPG in a prospective study. The authors found in 37 patients, the mean effectiveness period of RFA versus PRF was 5.21 versus 4.69 months, respectively, with no significant difference (21). Both RFA and PRF have been observed to be successful for headache pain, however, more studies are needed to directly compare the approaches.

Strengths and limitations

This study serves as an update to the literature of the evidence associated with RFA for management of chronic headache pain. Previous systematic reviews have been performed on the topic (46); however, this study uniquely highlights outcomes of ablation such as targeted nerves, pain scores, pain relief duration, functional status, and patient satisfaction levels. Understanding these outcomes is important in clinical practice to improve and optimize patient care. This review had several limitations including the retrospective nature of most studies and the lack of consistency of approach and targeted nerves. Further studies are needed to establish a headache RFA treatment protocol and provide clinicians with stronger strategies for treatment.

Conclusions

This study reviewed the evidence associated with RFA for treatment of chronic headache. RFA is a favorable treatment for headache that has shown benefit through pain scores, duration of pain relief, functional outcomes, and patient satisfaction levels. All the included studies show positive outcomes towards RFA for management of headache. This study was limited by its retrospective nature as each study had varying methodology. Additional, larger RCT studies are needed to better analyze the efficacy and safety of RFA in patients with chronic headache.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Annals of Palliative Medicine, for the series “Advances in Radiofrequency Ablation”. The article has undergone external peer review.

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://apm.amegroups.com/article/view/10.21037/apm-23-528/rc

Peer Review File: Available at https://apm.amegroups.com/article/view/10.21037/apm-23-528/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://apm.amegroups.com/article/view/10.21037/apm-23-528/coif). The series “Advances in Radiofrequency Ablation” was commissioned by the editorial office without any funding or sponsorship. A.A.E. served as the unpaid Guest Editor of the series and serves as an unpaid editorial board member of Annals of Palliative Medicine from June 2022 to May 2024. A.C. and F.S.A. received honorarium fees from Pain Medicine News. A.A.E. received the consulting fees from Avanos. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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