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  • Comparison of contralateral oblique view with the lateral view for fluoroscopic-guided cervical epidural steroid injection: a randomized clinical trial

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Original research
Comparison of contralateral oblique view with the lateral view for fluoroscopic-guided cervical epidural steroid injection: a randomized clinical trial
  1. Ji-Hoon Sim1,
  2. Hyun-Jung Kwon1,
  3. Chan-Sik Kim1,
  4. Eun Ha Kim1,
  5. Doo-Hwan Kim1,
  6. Seong-Soo Choi1 and
  7. Jin-Woo Shin2
  1. 1 Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
  2. 2 Asan Medical Center, Songpa-gu, Seoul, Republic of Korea
  1. Correspondence to Professor Doo-Hwan Kim, Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Songpa-gu, Republic of Korea; dh_kim{at}amc.seoul.kr

Abstract

Background Cervical epidural steroid injection is associated with rare but potentially catastrophic complications. The contralateral oblique (CLO) view may be a safe and feasible alternative to the lateral (LAT) view for fluoroscopic-guided cervical epidural steroid injection. However, evidence for the clinical usefulness of the CLO view for cervical epidural steroid injection is lacking. We assessed the clinical usefulness of the CLO view for cervical epidural steroid injection in managing cervical herniated intervertebral discs.

Methods Patients were randomly assigned to receive fluoroscopic-guided cervical epidural steroid injection under LAT view or CLO view at 50±5° degrees groups. The primary outcome was the needling time comparison between the two groups. Secondary outcomes were comparison of first-attempt success rate, needle tip visualization and location, total number of needle passes, final success rate, crossover success rate and false-positive/negative loss of resistance. Complications and radiation dose were also compared.

Results The needling time significantly decreased in the CLO than in the LAT group. The first-attempt success rate was significantly higher in the CLO compared with the LAT group. The needle tip was clearly visualized (p<0.001) and located more often on (or just anterior to) the ventral interlaminar line (p<0.001) in the CLO than in the LAT group. There were significantly fewer needle passes (p=0.019) in the CLO than in the LAT group. There were no significant differences in the final success, crossover success, false-positive/negative loss of resistance or radiation dose between the groups. Two (5.9%) cases in the LAT group experienced complications.

Conclusion The CLO view may be recommended for fluoroscopic-guided cervical epidural steroid injection, considering its better clinical usefulness over the LAT view.

  • neck pain
  • nerve block
  • pain management
  • chronic pain

Data availability statement

Data are available upon reasonable request. Not applicable.

https://doi.org/10.1136/rapm-2021-103177

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    Introduction

    Cervical epidural steroid injection (CESI) via the cervical epidural space is frequently conducted in patients with degenerative cervical spine diseases who have cervical radiculopathy with moderate-to-severe pain unresponsive to conservative treatment.1–3

    The cervical epidural space is anatomically relatively small compared with the thoracic or lumbar regions and approximates the brain components.4 Incorrect needle advancement and drug injections can lead to catastrophic complications.5 6 Depending on the approach, the interlaminar and transforaminal methods are typically used7–9; the loss-of-resistance (LOR) technique using saline or air is currently the most implemented in the interlaminar approach as a method to confirm the needle entry into the epidural space.10 Additionally, fluoroscopy using a contrast agent is widely used for accurate and safe access to the cervical epidural space and needle visualization.11

    Accessing the epidural space via the contralateral oblique (CLO) view is an alternative to the conventional lateral (LAT) view to improve needle tip visualization and provide consistent geometric landmarks.12–15 The CLO view can be attained by identifying the target lamina for which the needle tip is advanced, and subsequently focusing the image intensifier in an oblique manner in the direction opposite from the lamina.16 Although previous systematic image analyses have revealed that an angle of 50° may be the ideal CLO angle for the cervical epidural approach,13 17 18 data regarding the clinical usefulness of the CLO view are lacking. Therefore, we aimed to evaluate the clinical usefulness of the CLO view at 50±5° by assessing the needling time compared with that obtained via the LAT view in fluoroscopy-guided CESI in patients with cervical radiculopathy. Additionally, we compared the success rate of the first attempt, the total number of needle passes, final success rate, crossover success, needle tip visualization, needle tip location and false-positive/negative LORs between the CLO and LAT views.

    Methods

    Study design and participants

    This prospective study was conducted at the Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea, from December 2020 to June 2021. The Institutional Review Board of the Asan Medical Center approved this study (protocol number 2021-3013), registered at the Clinical Research Information Service (https://cris.nih.go.kr/cris/search/detailSearch.do/19805, KCT0005765) on 12 January 2021. Written informed consent was obtained from each participant before inclusion. This study was conducted in accordance with the Declaration of Helsinki. Patients who underwent cervical epidural block and epidural catheter insertion between 4 March 2021 and 10 June 2021, for cervical radicular pain and who did not respond to medication or physical therapy were assessed for eligibility. Patients aged 20–79 years and with any grade of cervical herniated intervertebral disc without cervical myelopathy on MRI or CT were included. Our exclusion criteria were: allergy to local anesthetics or contrast; infection, malignancy, psychiatric disorders; use of anticoagulants; previous surgery; inability to express pain on a numerical rating scale (NRS); signs of cervical myelopathy and refusal to participate in the study.

    Randomization and blinding

    Patients were divided into the LAT group or the CLO group. Block randomization was employed to assign equal numbers of patients to each group. The block sizes were randomly permuted to make the allocation process unpredictable. The first investigator provided an opaque, sealed envelope labeled with sequential study numbers to the pain physicians who conducted CESI on the day of the procedure. Although the pain physicians could not be blinded, all patients were blinded to the type of fluoroscopic view. The second investigator, who was not blinded to the allocation groups, assessed procedure-related outcomes in the operating room. The third investigator, blinded to the allocation groups, assessed the patients’ NRS in the neck, shoulder or arm preoperatively and re-evaluated the postprocedural NRS 1 month later.

    CESI procedures

    CESIs were performed in the prone position with a pulse oximeter, a blood pressure monitor and under fluoroscopic guidance. Needle insertion was initially performed under the anteroposterior view and a paramedian cervical epidural approach was performed at C6-7 or C7-T1 in all CESI procedures. The target site was chosen as C7-T1 for patients with lesions at C7-T1, and C6-7 for patients with lesions above that level, according to our institutional protocol. After skin infiltration with 1% lidocaine, a 22 G Tuohy needle (Green Medical Supply, Seoul, Korea) was used to access the epidural space. When the needle engaged with the ligamentum flavum, resistance to the needle was observed to increase. Subsequently, fluoroscopy (Ziehm Vision RFD, Ziehm, Nuremberg, Germany) was then obliqued contralateral to the needle tip at an angle of 50±5° (CLO group; figure 1A) or rotated at 90° (LAT group; figure 1B) to visualize the target interlaminar space and ventral interlaminar line (VILL: an imaginary line connecting the ventral laminar margins) or the spinolaminar line (an imaginary line connecting the anterior edge of the spinous processes). To optimize the CLO view, based on 50°, ±5° of adjustment was allowed. The needle was advanced without an LOR technique until just before the VILL in the CLO group or just before the spinolaminar line in the LAT group.13 At this point, the needle was cautiously advanced further using the LOR-to-air technique until the epidural space was reached. If LOR was obtained, 0.5 mL of contrast medium (Omnipaque 300, GE Healthcare, Little Chalfont, UK) was administered to confirm the epidural space through CLO (figure 1C), LAT (figure 1D) and anteroposterior fluoroscopy views (CLO group; figure 1E, LAT group; figure 1F), followed by a 3 mL mixture of 5 mg dexamethasone and 1% lidocaine.

    Figure 1
    Figure 1

    Fluoroscopic images of the contralateral oblique and lateral views in patients receiving cervical epidural steroid injection. (A) Contralateral oblique fluoroscopic view showing the needle tip located along the ventral interlaminar line. (B) Lateral fluoroscopic view showing the needle tip located beyond the spinolaminar line. (C) Contralateral oblique fluoroscopic view showing the spread of the contrast medium along the ventral interlaminar line. (D) Lateral fluoroscopic view showing the spread of the contrast medium in the epidural space. (E) Anteroposterior fluoroscopic view showing the spread of the contrast medium and final needle tip location in the contralateral oblique group. (F) Anteroposterior fluoroscopic view showing the spread of the contrast medium and final needle tip location in the lateral group.

    Demographic characteristics and outcome assessments

    Demographic characteristics included age, sex, body mass index (BMI), NRS before and after the procedure, target level and the insertion site. The pre-NRS was measured immediately before the procedure, and the post-NRS was measured either at outpatient visits or via a telephone interview 1 month after the procedure.19 20 Primary outcomes included assessing the needling time (procedural time from the skin puncture to contrast medium administration after reaching the epidural space) during the procedure between the groups. Secondary outcomes included comparing success rates of the first attempt (achieving successful epidural access without any backward movement of the needle and confirmation of contrast dispersion in the epidural space), the total number of needle passes (first needle pass plus additional needle passes, that is, readvancement of the needle after any needle withdrawal to change the direction), final success rate (achievement of successful epidural access and confirmation of contrast dispersion in the epidural space within three attempts of needle passes), crossover success (achieving successful epidural access by using another method, if the primary process failed; needle passes allowed up to three times per skin puncture only in the primary process), needle tip visualization, needle tip location and false-positive/negative LOR between the groups. A false-positive LOR was defined when the needle was not actually placed in the epidural space, although LOR was obtained. A false-negative LOR was identified when the needle was placed in the epidural space, although LOR was not obtained. When either a false-positive or false-negative LOR was detected, the epidural needle location was confirmed on fluoroscopy by the epidural spread of the contrast medium. Additionally, complications such as subarachnoid injection, dura puncture and intravascular injection were evaluated. The follow-up period for complications was from immediately after the procedure until the outpatient visit after 1 month. The cumulative total radiation dose obtained from the fluoroscopic report during the procedure was also evaluated.21

    Fluoroscopic finding analysis

    Three investigators who did not participate in the procedure analyzed the fluoroscopic images by majority consensus. In the CLO and LAT views, each grade for the visualization and location of the needle tip was defined with some modifications from previous studies.13 14 Needle tip visualization was categorized as grade 1 (clearly visualized without ambiguity), grade 2 (poorly visualized or visualized with effort) or grade 3 (indicated nearly not or not visualized). In the CLO view, the region anterior to the VILL and posterior to the ventral foraminal line was divided equally into three zones. The oblique zone 1 is far posterior, while oblique zone 3 is the frontmost; oblique zone 2 is in the center (online supplemental figure 1A). In the LAT view, the region extending from the spinolaminar line to the posterior articular pillar line was divided equally into two zones; lateral zone 1 and lateral zone 2 from posterior to anterior. Lateral zone 3 extended from the posterior articular pillar line to the posterior vertebral line (online supplemental figure 1B). The location of the needle tip in the CLO or LAT views was defined, respectively, as follows: grade 0 (on the VILL or the spinolaminar line), grade 1 (between the VILL and the oblique zone 1; just anterior to the VILL or between the spinolaminar line and lateral zone 1; just anterior to the spinolaminar line), grade 2 (deeper than oblique zone 1; significantly anterior to the VILL or deeper than the lateral zone 1; significantly anterior to the spinolaminar line) and grade 3 (undetermined grade; needle tip location could not be evaluated due to lack of visualization).

    Supplemental material

    Statistical analysis

    Based on investigations performed at our institution, we calculated the required sample size according to the average needling time; the average value and SD of the needling time were 126.6±65.0 s under the fluoroscopic LAT view. The difference of the average values of needling time between the LAT view and CLO view was assumed to be approximately 30%; thus, the needling time was assumed to be 88.6±45.5 s in the CLO group. In the two-sided test with a significance level of 0.05, with the desired power of 80% and the allocation ratio at 1:1, the required number of samples was approximately 36 in each group. Assuming a dropout rate of 5%, a total of 76 patients were considered as ideal and equally allocated to each group. A χ2 or Fisher’s exact test was used to analyze qualitative data. The independent t test or Mann-Whitney test was used to compare quantitative variables. Data are presented as mean (SD), median (IQR) and number (proportion). The data were analyzed with SPSS V.22 (IBM, Armonk, New York) with p value <0.05 considered as statistically significant.

    Results

    Study population

    A total of 95 patients were screened for eligibility; 19 patients refused to participate in the study. A total of 76 patients fulfilled the inclusion criteria and were randomized to each group. Two patients in the CLO group and four in the LAT group did not receive the allocated treatment because of improved symptoms. Finally, 36 patients in the CLO group and 34 patients in the LAT group were analyzed (figure 2). Baseline demographic characteristics of each group are shown in table 1. Although pre-NRS and post-NRS scores did not differ between the groups (p=0.167 and p=0.259), the median NRS significantly decreased from 6.0 (5.0 to 6.0) to 2.5 (2.0 to 4.0) after the procedure in the CLO group and from 5.0 (4.8 to 6.0) to 2.5 (2.0 to 4.2) after the procedure in the LAT group procedure, respectively (p<0.001 in both groups). However, there were no significant differences in the demographic and interventional characteristics between the groups (table 1).

    View this table:
    Table 1

    Clinical characteristics of the study subjects

    Figure 2
    Figure 2

    Flow diagram of the study. CLO, contralateral oblique; LAT, lateral.

    Study outcomes

    Table 2 shows the procedural variables during the CESI. The needling time during the procedure was significantly shorter in the CLO group than in the LAT group (86.5±37.6 vs 145.9±58.0 s, p<0.001) (table 2). The first-attempt success rate was significantly higher in the CLO group (97.2% vs 67.6%, p=0.001) (table 2). There were significantly fewer needle passes in the CLO group than in the LAT group. In the CLO group, 35 (97.2%) patients experienced needle passage once, while one (2.8%) patient experienced three needle passages. In the LAT group, 24 (70.6%) patients experienced needle passage once, while 10 (29.4%) patients experienced two or more needle passages (p=0.019) (table 2). There were no significant differences between the groups in final success (100% vs 94.1%, p=0.232) or crossover success (0% vs 5.9%, p=0.232).

    View this table:
    Table 2

    Procedural variables during the cervical epidural access

    All needle tips in the CLO group were clearly visualized without ambiguity (ie, grade 1) compared with that in the LAT group (100% vs 47.0%, p<0.001) (table 2). In the LAT view, 10 (29.4%) and 8 (23.5%) cases were categorized to grade 2 and grade 3, respectively. There were no needle tip visualizations (grade 2 or 3) in the CLO view. The needle tip locations between the groups are shown in figure 3. More needle tips were located on or just anterior to the VILL in the CLO group than in the LAT group (52.8% vs 0% in grade 0, 44.4% vs 32.4% in grade 1, 2.8% vs 50.0% in grade 2, 0% vs 17.6% in grade 3, p<0.001) (figure 3). Although the incidence of false-positive/negative LORs was higher in the LAT group, there were no significant differences between the groups (20.6% vs 5.6%, p=0.080 in false-positive LOR, 0% vs 2.9%, p=0.486 in false-negative LOR, respectively) (table 2).

    Figure 3
    Figure 3

    Comparison of grade of needle tip location between CLO view and LAT view. CLO, contralateral oblique; LAT, lateral.

    Complications and radiation dose

    Serious complications, such as spinal cord trauma and subarachnoid injection, were not encountered in either group. We observed two (5.9%) cases of complications in the LAT group, one each of dural puncture and intravascular injection (intravascular uptake of contrast). Conversely, in the CLO group, no complications were observed. However, there was no significant difference between the groups in terms of incidence of complications (p=0.232). The radiation dose was higher in the LAT than in the CLO group; however, there was no significant difference between the groups (42.1±36.5 vs 37.0±19.6 cGy×cm2, p=0.470).

    Discussion

    Our study demonstrated that the CLO view at an angle of 50±5° was more useful than the LAT view in performing CESI, allowing a shorter needling time, higher first-attempt success and decreased total number of needle passages. Additionally, in the CLO view, there was no evidence of CESI-related complications. These results indicate that the CLO view at 50±5° can provide clinical benefits over the LAT view for performing fluoroscopy-guided CESI.

    For fluoroscopy-guided CESI, the LAT view has been traditionally considered for visualizing the advancement of the needle tip into the dorsal spinal canal and evaluating the anatomical landmarks, such as the spinolaminar line.22 However, needle tip visualization in the lower cervical and cervicothoracic area is often challenging because the needle tip and cervical spine, including the spinous process and spinolaminar line, are usually obscured by the shoulder in the LAT view.23 A previous study showed that the needle tip was not visualized in nearly one-fourth of cases.13 Recent studies have suggested that the CLO view may be an alternative to the LAT view.12–17 Landers et al reported that the CLO view can serve as a more reliable and consistent geometrical landmark for the cervical interlaminar epidural space.18 Gill et al suggested that each CLO view at 50 and 45° was superior to the LAT view in the cervical and lumbar epidural region, respectively.14 15 Park and Lee reported that the CLO view was superior to the LAT view and comparable to CT guidance for performing CESI.24 However, previous studies have been conducted on single subjects or mainly reported on the anatomical geometry, such as contrast-spread patterns and needle tip visualization and location. To our knowledge, there are no trials showing the clinical usefulness of the CLO view in CESI; this is the first randomized clinical trial that comprehensively evaluated not only the geometric aspects but also the clinical usefulness between the CLO view and the LAT view in multiple subjects.

    In this study, the needling time was significantly decreased in the CLO view compared with the LAT view. When performing CESI, reducing the procedure time is important because patients experience significant trouble related to fear, anxiety, stuffiness and uncomfortable postures associated with a face down prone position under the drapes. Although the procedure time in our study was approximately 2 min, the needling time can be much longer especially in case of trainees and novices. Therefore, the CLO view can provide a greater advantage in reducing the needling time for beginners, who are not proficient in the actual clinical practice.22

    A decreased procedure time may result from an increased first-attempt success rate due to clear needle tip and laminar visualization in the CLO view. In the present study, in the LAT view, only 16 (47.0%) patients showed clearly visualized needle tips, whereas in the CLO view, all patients (100%) showed clearly visualized needle tips. A clear needle tip and laminar visualization can help the operator recognize and correct for proper location of the needle tip and help the physician advance the needle without encountering the lamina.25

    In our study, needle tips were located on or between the spinolaminar line and lateral zone 1 in only 12 patients (35.3%) with the LAT view. In contrast, in the CLO view at 50±5°, the needle tips were located on the VILL or between the VILL and oblique zone 1 in 35 patients (97.2%). This is crucial for procedural safety because under the CLO view, the physician can anticipate the locus of the epidural space. These advantages of the CLO view can reduce total needle passes and increase first-attempt success rate, subsequently decreasing the procedure time.

    There were two total complications including dural puncture in the LAT view. Despite various maneuvers, such as fluoroscopy adjustment, caudal manipulation of the shoulders and the swimmer’s view,23 26 visualization of the needle tip can be impaired by a short neck, obesity and the projection of the shoulders in the LAT view. Moreover, considering the circumferential characteristics of the epidural space, the LAT view has a geometrical limitation in visualizing the correct position of the needle tip in the epidural space.18 27 Although this study did not report the safety of the CLO view, it has been suggested that the CLO view at 50±5° may ensure geometrical safety, including accurate depth of the needle tip in relation to the epidural space, during fluoroscopy-guided CESI.28 In our study, one case of dural puncture occurred with a false-negative LOR in the LAT view, whereas neither a dural puncture nor a false LOR occurred in the CLO view. Additionally, although not statistically significant, the incidence of false-positive LOR was higher in the LAT view than in the CLO view (20.6% vs 5.6%). These results may be explained, at least in part, by the fact that the CLO view helps discriminate between true and false LORs.29 The low incidence of false LOR in the CLO view could also contribute to the increased success rates, decreased procedure time and improved procedure safety.

    This study has a few limitations. First, the procedure results may vary depending on the individual characteristics and skills of the operator. However, in our study, CESI was performed by two physicians with more than 7 years of proficient experience in performing this procedure, using the same techniques (such as a paramedian approach), in both groups. Second, compared with previous studies,14 a detailed geometrical analysis was insufficient. However, because essential and clinical results were included in the analysis, further geometric analysis may not have influenced the main results of this study. Third, although there was no evidence of significant CESI-related complications in the CLO view, the sample size was insufficient to evaluate its overall safety. A well-designed prospective study on the safety of the CLO view is needed in the future. Fourth, it was impossible to blind the physicians to the allocated intervention and the investigators to the measurements of the study outcomes, such as needling time and first-attempt success; this may have biased the study outcomes. However, we attempted to be as objective and truthful as possible in this regard. Fifth, patients with high BMI, spinal pathologies or previous cervical spine surgery were not included in this study. Therefore, future prospective studies including such patients are required. Sixth, using the paramedian approach, the CLO view at 50±5° can be suitable when locating the needle tip lateral to the spinous processes; in other conditions, the CLO view at 50±5° may be inappropriate. Therefore, further clinical studies aiming to identify the optimal angle for the CLO view according to various conditions are needed.

    In conclusion, considering the clarity of the needle tip visualization, consistent needle tip location and the better clinical usefulness, including a shorter needling time, higher first-attempt success and decreased total number of needle passage compared with the LAT view, the CLO view at an angle of 50±5° may be recommended for fluoroscopic-guided CESI using the paramedian approach.

    Data availability statement

    Data are available upon reasonable request. Not applicable.

    Ethics statements

    Patient consent for publication

    Ethics approval

    The study was approved by the Institutional Review Board of the Asan Medical Center (2021-3013) and was registered at Clinical Research Information Service (KCT0005765).

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    Footnotes

    • Contributors J-HS: conception, design and conduct of the study; analysis and interpretation of data; reporting; and writing―original draft preparation. H-JK, C-SK, EHK: data curation and acquisition; analysis and interpretation of data. S-SC: conception, design and conduct of the study. JWS: supervision; and project administration. D-HK: planning, conception, design and conduct of the study; writing―review and editing of the manuscript; supervision; and project administration. D-HK (guarantor) accepts full responsibility for the finished work and/or the conduct of the study. All authors revised the manuscript critically for important intellectual content. All authors gave approval for the final manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.