Radicular Pain Management Using Ultrasound-Guided Versus Fluoroscopy-Guided Epidural Steroid Injections: A Systematic Scoping Review of Comparative Studies

Back pain is the leading cause of disability globally and results in a substantial medical and economic burden. Epidural steroid injections (ESIs) have been widely used as a treatment for back pain with radiculopathy of various etiologies. Ultrasound guidance (UG) for delivering ESIs can reduce costs and facilitate the procedure in resource-limited settings compared to the current standard technique of using fluoroscopic guidance (FG). This scoping review aimed to compare the clinical outcomes between UG and FG ESIs in the treatment of radicular pain. Systematic searches of Embase, Ovid Medline, Scopus, CENTRAL (Cochrane Central Register of Controlled Trials), CDSR (Cochrane Database of Systematic Reviews), and ClinicalTrials.gov were conducted in accordance with PRISMA-ScR (Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for scoping reviews) guidelines. Randomized controlled trials (RCTs) and comparative observational studies investigating the outcomes between UG and FG ESIs in the treatment of radicular pain were included. The risk of bias for included RCTs was assessed using the Cochrane Collaboration risk-of-bias tool. From 1,659 potentially relevant publications, eight studies (five RCTs and three retrospective comparative studies) were included. Five of the studies were conducted in the Republic of Korea, one in China, one in India, and one in Egypt. All studies reported no significant difference between UG and FG ESIs in success rate, pain index, and postoperative disability (p > 0.05). One study reported increased intravascular injections in the FG group, but this did not reach statistical significance (p > 0.05). One study reported decreased needle-placement time in the UG group (p < 0.001). One study reported decreased total operation time in the UG group (p < 0.05). Overall, treatment outcomes and adverse events profile are comparable between UG and FG ESIs for radicular pain. UG ESIs reduce costs, minimize radiation exposure, facilitate vessel identification, prevent injury, and potentially save intraoperative time while offering the same benefits as FG injections. Future studies should focus on long-term outcomes, cost-effectiveness, and the impact of UG ESIs on patient satisfaction and quality of life.


Introduction And Background
Back pain is a ubiquitous and often debilitating medical condition affecting millions worldwide, significantly impacting their quality of life and productivity [1].It is a leading cause of disability, making it a substantial burden on healthcare systems and economies [2].The lifetime prevalence of back pain is estimated to be approximately 84% in adults, with around $200 billion spent each year in managing this condition [3].The etiologies of back pain are numerous and include traumatic, degenerative, oncologic, inflammatory, metabolic, postural, and idiopathic.Determining the etiology of back pain is often a painstaking process that requires a thorough history and physical examination and oftentimes various modalities of imaging [4].
The approach to the treatment of back pain varies depending on the underlying cause, and the physician must first identify the presence of any red flags (e.g., fever, focal tenderness to palpation) to rule out lifethreatening emergencies such as infectious or oncologic causes [5].First-line treatments for back pain are typically non-pharmacologic and include patient education, physical therapy, superficial heat application, acupuncture, massage, and continuation of normal routines while avoiding activities that precipitate pain [6].Second-line pharmacologic treatment can include nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and muscle relaxants [7].
Radiculopathy is a common cause of back pain and results when a spinal nerve root is compressed or irritated [8].The most common cause of radiculopathy is a herniated disc, but regardless of the underlying cause, a cornerstone in the treatment of radicular pain is epidural steroid injections (ESIs) [9].ESIs are the most performed procedure for pain management in the United States and have been shown to reduce pain, restore function, and delay invasive surgery [10].ESIs are considered a less risky treatment option compared to opioids, which have the potential for abuse [11].
ESIs induce pain relief primarily through the reduction of inflammation [10].Corticosteroids inhibit phospholipase A2, preventing the production of pro-inflammatory eicosanoids which can induce pain.It is also hypothesized that ESIs induce pain relief via lavage of the epidural space.A systematic review conducted by Rabinovitch et al. found a positive correlation between larger volumes of fluid injected into the epidural space (irrespective of the injected medication) and greater relief of radicular pain [12].
Delivery of ESIs typically involves fluoroscopic guidance (FG), and less frequently, computerized tomography (CT) to ensure proper needle placement [13].This has become the standard of care, although recent studies have shown ultrasound-guided (UG) ESIs to be a safe, reliable, and radiation-free alternative to fluoroscopy [14,15].In recent years, UG ESIs have gained attention for the potential advantages they can provide over FG ESIs, such as the lack of radiation exposure, equipment mobility, and visualization of softtissue and real-time needle trajectory.Current research on this topic remains limited.This systematic scoping review aims to summarize the potential advantages that UG ESIs can provide over FG ESIs and to evaluate the current literature on this topic to characterize the evidence regarding the efficacy and safety between these two imaging modalities.

Review Methods
We conducted a scoping review following the methodological framework proposed by Arksey and O'Malley [16] and its recent update by Levac et al. [17].The conduct and reporting of this scoping review were also guided by the Joanna Briggs Institute Methods Manual for Scoping Reviews [18].This approach ensured a comprehensive exploration of the literature relevant to our research objectives.
This protocol was registered with the Open Science Framework (OSF) (https://osf.io/tjc8h)aligning with established transparency practices in scoping review methodology.The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) extension for scoping reviews (PRISMA-ScR) was used to guide our reporting [19].

Eligibility Criteria
Eligible studies were included based on the following criteria: (1) randomized controlled trials (RCTs) or comparative observational studies investigating the outcomes between UG FG ESIs in the treatment of radicular pain; (2) study population consisting of patients 18 years old or older with radicular back pain; and (3) English-language publications.Exclusion criteria were as follows: (1) studies other than RCTs and comparative observational studies; (2) studies in which ultrasound-guided steroid injection was not compared to fluoroscopy-guided injection; (3) studies that did not report a primary outcome; and (4) non-English transitions to studies.

Data Sources and Study Identification
A specialist medical librarian (LHY) searched article databases and clinical trial registers from inception for relevant records including the concepts of UG or FG and radicular pain and epidural injection.

Study Selection
All records identified in the search were imported into Covidence.org.Two reviewers (AH and WH) independently assessed the identified citations for eligibility based on the title and abstract.The abstracts included were subsequently screened in full text according to the inclusion and exclusion criteria.Differing opinions were resolved through discussion or a third author's judgment (ISA).Reference lists of identified full-text articles were searched for additional studies.

Data Extraction
Data from included records were extracted into a Microsoft Excel, version 16 (Microsoft Corporation, Redmond, WA, USA) spreadsheet.The reviewers collected relevant characteristics from each study, including author, publication date, country, number of patients, demographic characteristics, severity of diabetic foot, and reported outcome measures.

Quality Appraisal/Risk-of-Bias Assessment
Two reviewers (AH and WH) independently assessed the quality of each included study using the Cochrane Collaboration tool for assessing risk of bias [21], assessing the following domains: selection bias, performance bias, detection bias, attrition bias, reporting bias, and other biases.The Newcastle-Ottawa Scale was used to assess the risk of bias in observational studies [22,23].

Data Analysis
Due to the heterogeneity in the methods and outcome measures of the included studies, statistical comparisons were not feasible.Consequently, a narrative description of the data was chosen as an appropriate method to achieve this study's aims.This methodology is commonly employed in evidencebased journals and databases [24,25].The authors systematically analyzed all reported outcomes from the included studies.They performed a thematic analysis and reported only those findings that aligned with the objectives of the work.

Literature Search
The initial search strategy identified 2,127 records and 286 new results were found in the updated search (2,539 records).After excluding duplicates (n = 880), 1,659 unique articles were independently screened by title and abstract and assessed for eligibility.An additional 1,647 records were excluded through title and abstract screening.Twelve full-text articles were retrieved for further evaluation.Of these, four were excluded for the following reasons: wrong population (n = 3) and non-English language (n = 1).Overall, eight articles met the inclusion criteria.Figure 1 illustrates a PRISMA diagram outlining the literature search and study selection process.

Risk-of-Bias Assessment
The quality of the included RCTs was appraised according to the Cochrane reviewers' handbook [34].All five of the included RCTs outlined specific randomization techniques which the authors of this review considered to be at low risk of bias [26][27][28][29][30]. Four of the five included RCTs described blinding techniques during data analysis and evaluation of treatment success [26,27,29,30].None of the RCTs commented on patient blinding during the administration of treatment as blinding the provider to the imaging modality (ultrasound vs. fluoroscopy) is not feasible.All five RCTs included in this study showed comparable baseline data between the control and treatment groups.Figure 2 shows an illustration of the risk of bias in the included RCT studies (details in Appendix B).

FIGURE 2: Risk of bias of included RCTs
RCT: randomized control trial

Length of Procedure
Two RCTs measured the time required for proper placement of the needle [28,29].Both studies reported that the total operation time and the time required for proper needle placement were significantly shorter in the UG group as compared to the FG group.

Complications
None of the included studies reported significant adverse effects of ESIs in either the UG or FG groups.
However, it appears that FG ESIs may lead to an increased risk of intravascular injection.Park et al. reported two cases of intravascular injection in the FG group with none in the UG group [26].Jee et al. reported five cases of intravascular injection in the FG group with none in the UG group [27].Similarly, Jang et al. reported nine cases of intravascular injection in the FG group with none in the UG group [33].

Discussion
This systematic scoping review characterized the evidence regarding the efficacy and safety of UG and FG ESIs for radicular back pain and identified areas where further research is needed to strengthen the evidence base and guide clinical practice.ESIs have traditionally been performed under fluoroscopic guidance [14].However, healthcare providers are receiving earlier exposure and better training in the use of ultrasound imaging, and the incorporation of ultrasound into the delivery of ESIs has the potential to save the healthcare industry and patients significant financial costs [29,35].Specifically, the data suggest that UG ESIs are comparable to FG ESIs in terms of pain relief and recovery of motor function.All of the included studies reported no significant difference between the UG and FG groups in various pain and disability assessment outcome measures (VNS, VAS, NDI, ODI, etc.).
Additionally, the two studies that assessed the length of the procedure between the two groups found that ultrasound guidance resulted in a shorter procedure time and faster placement of the needle in the proper position [28,29].The differences were significant in both cases, suggesting that ultrasound guidance can provide a benefit to both providers and patients by facilitating a faster procedure.
Although no significant adverse events were reported in the included studies, it is notable that three studies found cases of intravascular injection in the FG group, and no cases in the UG group [26,27,33].This is likely due to the advantage that ultrasound imaging provides of direct, real-time visualization of soft tissue structures and bony surfaces, facilitating needle manipulation and avoidance of vessels and soft tissue structures [14,15].
Overall, the use of ultrasound appears to provide significant advantages over fluoroscopy such as reducing the length of the procedure, reducing exposure to ionizing radiation [36], and facilitating the avoidance of intravascular injections by allowing for real-time visualization of needle placement, all while providing comparable efficacy in terms of pain relief and recovery of motor function.

Strengths and Limitations
This was the first review to explore the literature examining the efficacy and safety of UG versus FG ESIs for the management of radicular back pain.The study was strengthened by the systemic searches of the literature using large bibliometric databases.This scoping review has several limitations.Only Englishlanguage articles were included, which may have resulted in the exclusion of significant studies published in other languages.Additionally, non-comparative studies were not included which may have limited the identification of all relevant studies using UG ESIs.

Conclusions
By focusing on the efficacy and safety of ultrasound guidance (UG) compared to fluoroscopic guidance (FG) epidural steroid injections (ESIs), this scoping review has highlighted the potential advantages that ultrasound can provide, such as real-time visualization of needles and the avoidance of ionizing radiation.Future studies should focus not only on assessing efficacy and complication rates between the two imaging modalities, but also on long-term outcomes, cost-effectiveness, and the impact of UG ESIs on patient satisfaction and quality of life.

FIGURE 1 :
FIGURE 1: PRISMA scoping review flow diagram outlining the selection process PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; RCT: randomized controlled trial in both groups at the 30minute, 1-week, and 1-month post-injection time points.No statistical differences were observed between both groups.Operation time was less using ultrasound guidance as compared to fluoroscopy guidance (518 ± 103 vs. 929 ± 228 s, respectively, p < 0.05).significantly improved in both groups at the 1-month, 3-month, and 6-month post-injection time points.No statistical differences were observed between both groups.Five cases of intravascular injections were observed only in the fluoroscopy-guided group without significant differences between the groups., straight leg raising, and modified Schober test significantly improved in both groups at the 1-month and 3month post-injection time points.No statistical differences were observed between both groups.significantly improved in both groups at the 1-month, 3-month, and 6-month post-injection time points.No statistical differences were observed between both groups.Intravascular contrast spread was noted during injection in nine patients who received fluoroscopy-guided injections.

TABLE 1 : PICOs of included studies
Epidural/ OR exp Analgesia, Epidural/ OR exp Injections, Epidural/ OR exp Spinal Nerve Roots/ OR epidural.ti,ab,kf.OR ((dural OR extradural OR peridural OR nerve OR transforaminal) ADJ2 (block* OR anaesthesia OR anesthesia OR injection*)).ti,ab,kf.OR (nerve root OR SNRB OR CESI OR nerve radix OR neutral root OR radix nervi).ti,ab,kf.)OR epidural:ti,ab,kw OR ((dural OR extradural OR peridural OR nerve OR transforaminal) NEAR/2 (block* OR anaesthesia OR anesthesia OR injection*)):ti,ab,kw OR ("nerve root" OR SNRB OR CESI OR "nerve radix" OR "neutral root" OR "radix nervi"):ti,ab,kw) Risk of Bias in the Included RCTs The participants were randomly assigned to one of two groups using a computer-generated randomization table: US and FL groups."To avoid research bias, pain, function, and satisfaction scores were evaluated by a third person or a researcher totally blinded to the entire procedure of this study or the methods used."To avoid research bias, pain, function, and satisfaction scores were evaluated by a third person or a researcher totally blinded to the entire procedure of this study or the methods used." with more than 7 yrs of experience in musculoskeletal image, who was blinded to the injection methods, judged all radiographs simultaneously by consensus."Four patients in the US group and two patients in the FL group were excluded for no improvement or worsening of pain during the first follow-up period, after the first injections.Three patients in the FL group were excluded, with two patients with peripheral injections (shoulder and knee) and one patient having been administered medication other than acetaminophen.One patient in the US group with a peripheral injection (hip) was also excluded."No patients were lost to follow-up.