Does Paramedian Approach Preferentially Secure Optimal Drug Delivery Onto Ventral Epidural Space and Subsequent Superior Clinical Efficacy Over a Dorsal Midline Approach During Cervical Interlaminar Epidural Injection?

BACKGROUND: There is paucity in the literature directly comparing the clinical results between the paramedian and the midline interlaminar cervical epidural injections. OBJECTIVE: To compare the proportion of ventral epidural spread of injectate and consequent clinical outcome between the paramedian and midline approach during interlaminar epidural injection in patients with axial neck and/or interscapular pain triggered from the underlying cervical spine pathologic condition. STUDY DESIGN: Retrospective study. SETTING: Primary pain clinic and spine hospital. METHODS: Two hundred and twenty-three patients with axial neck and/or interscapular pain due to cervical problem underwent interlaminar epidural injection through either a paramedian approach (PM group, n = 93) or a midline approach (ML group, n = 130). We compared the portion of ventral epidural filling, Numeric Rating Scale (NRS), and McNab criteria between both groups. The NRS and McNab criteria were also separately compared between the ventrally spread (VS) group and non-ventral spread (non-VS) group inside each PM and ML group, respectively, at 2 weeks and 10 weeks post-injection. RESULTS: The PM group showed a significantly higher proportion of ventral spread, successful NRS reduction, and satisfactory McNab criteria than the ML group at 10 weeks. In the PM group, the VS group showed the same results as above compared to the non-VS group. LIMITATIONS: A retrospective analysis based on the relatively short-term follow-up period clinical results. CONCLUSIONS: The paramedian approach showed the better direct injectate transfer over the ventral epidural space and subsequently superior clinical efficacy for the patients suffering from axial neck and/or interscapular pain secondary to cervical spine problems. KEY WORDS: Cervical disease, epidural injection, interlaminar, paramedian, midline, ventral epidural spread, Numeric Rating Scale, McNab criteria

Proposed Ionizing Radiation Doses of 3711 Fluoroscopy-Guided Epidural Injections

Background: Since fluoroscopy-guided interventional therapies grew significantly in recent years, exposure to ionizing radiation (IR) either for patient or medical staff became a critical issue. IR exposure varies according to the physicians’ experience, patients’ body mass index (BMI), imaging techniques and type of the procedure performed. The purpose of this study is to calculate the reference IR doses for fluoroscopy-guided epidural injections per procedure and BMI to provide reference doses for potential use in future dose reduction strategies. Methods: A retrospectively, evaluation of patients who received epidural steroid injections between January 2015 and December 2020 in a university hospital interventional pain management center, was performed. This observational study was conducted with patients aged  18 who underwent 3711 epidural injections including cervical interlaminar, lumbar interlaminar, lumbar transforaminal and caudal approaches. Provided IR doses for each patient were also divided by patients’ BMI to obtain dose per BMI. Results: The highest IR dose per procedure was found in caudal epidural injection with 0.218 mGy m2 and lowest dose was in cervical interlaminar epidural injection with 0.057 mGy m2. The IR dose per procedure was 0.123 mGy m2 for lumbar transforaminal and 0.191 mGy m2 for lumbar interlaminar epidural injection. Caudal epidural injection had also the highest IR dose per BMI which was 0.00749 and cervical interlaminar epidural injection had the lowest radiation dose per BMI which was 0.00214. Conclusions: We proposed reference IR dose levels of four approaches of epidural injections obtained from 3711 injections performed in a university hospital pain medicine clinic. BMI of patients were taken into account with the dose levels of injections given per BMI. Multicenter research with standardized techniques will assure more reliable reference levels which will guide pain physicians to self-assess their own levels of radiation exposure.

Evaluation of Contrast Flow Patterns with Cervical Interlaminar Epidural Injection: Comparison of Midline and Paramedian Approaches

Background and objectives: The purpose of this study was to compare and to analyze contrast spread patterns between the paramedian and midline approaches to cervical interlaminar epidural injection (CIEI). Materials and Methods: We retrospectively enrolled 84 CIEI cases that had been performed for unilateral cervical spinal pain from April 2019 to April 2020. After 3 mL of contrast had been injected into the epidural space, fluoroscopic images were obtained. The CIEI was divided into a midline (Group M, n = 42) and a paramedian (Group P, n = 42) approach by anteroposterior imaging. The P Group was classified into a more medial (Group Pm, n = 26) and a more lateral (Group Pl, n = 16) group. Using ImageJ on an anteroposterior image, we assessed the grayscale brightness ratio of the ipsilateral or contralateral side of the vertebral body as well as the intervertebral disc space one level just above the needle location. We identified the dispersion of contrast into the ventral epidural space. Results: The grayscale brightness ratio was significantly higher in Group P than in Group M (p < 0.001). The incidence of ventral epidural spread in Group M was 57.1% versus 88.1% in Group P, which was significantly different (p = 0.001). Conclusions: The fluoroscopic CIEI finding in the paramedian approach predominantly showed an excellent delivery of the injectate to the ipsilateral side in comparison to the contralateral side. This showed a greater advantage in delivery toward ventral epidural space as compared to the midline approach.

Analysis of Subdural Injection During Lumbar Interlaminar Epidural Injection in Failed Back Surgery Syndrome

Persistent or recurrent back and leg pain following spinal surgery, known as failed back surgery syndrome (FBSS), significantly limits daily life activities. A lumbar epidural injection can reduce adhesions, inflammation, and nerve compression, although the epidural space can be distorted due to dura mater and epidural tissues changes after spinal surgery. This study analyzed subdural injection during lumbar epidural injection in FBSS patients. We retrospectively analyzed data from 155 patients who received a lumbar interlaminar epidural injection to manage FBSS. We grouped the patients based on the injected contrast medium appearance in the subdural (group S) or epidural spaces (group E) in fluoroscopic contrast images. Demographic, clinical, surgical and fluoroscopic data were recorded and evaluated, as were the pain scores before and after injection. There were 59 patients (38.1%) in the subdural group. Injection distance from the surgery level differed between the groups. Risk of subdural injection at level 1 distance from the surgery level had an odds ratio of 0.374, and at level ≥2, it was 0.172, when compared to level 0. Subdural incidence differed with the distance from surgical site. Physicians should strive to reduce subdural incidence when the injection is planned at surgery site in FBSS.

Incidence of Unintentional Flow of Contrast into the Facet Joints During Fluoroscopy-Guided Cervical Interlaminar Epidural Injections: A Retrospective Cohort Study

Objective We sometimes encounter unintentional flow of contrast into the facet joints during cervical interlaminar epidural injection, which leads to false-positive epidural injection. The purposes of this study were to evaluate the rate of facet flow of contrast and to investigate various factors associated with injection into the space of Okada during fluoroscopy-guided cervical interlaminar epidural injection. Setting and Subjects Images from consecutive cases of fluoroscopy-guided cervical interlaminar epidural injection performed at a single institution between July 2015 and July 2018 were obtained and reviewed. Methods Cases of epidural injection were classified as either facet flow or no facet flow. Multivariate logistic regression was used to identify the predictive factors of unintended injection into the Okada space. Results A total of 2,006 cases were included. Intra-articular flow was identified in 6.0% of cases (121/2,006). All cases of flow of contrast into the facet joints were recognized, and appropriate epidurograms were obtained during the procedures. The highest rate of unintended facet flow of the contrast (10.1%, 44/436) occurred at C5–6. Cervical interlaminar epidural injection at C5–6 and above (adjusted odds ratio [aOR] = 1.929, P = 0.001) and the paramidline approach for epidural injection (aOR = 2.427, P &lt; 0.001) were associated with injection into the space of Okada. Conclusions We detected injection into the space of Okada during fluoroscopy-guided cervical interlaminar epidural injection in 6.0% of procedures. Cervical interlaminar epidural injection at C5–6 and above and the paramidline approach for epidural injection were positive predictors of unintentional facet flow of the contrast.

A Prospective Comparison of CT-Epidurogram Between Th1-Transforaminal Epidural Injection and Th1/2-Parasagittal Interlaminar Epidural Injection for Cervical Upper Limb Pain

Background: Cervical epidural injections for treating neck and upper limb pain are performed by 2 methods: transforaminal and interlaminar. Many serious complications caused by inadvertent intravascular injection have been reported with the use of cervical transforaminal epidural steroid injection through the anterior-lateral approach. Despite international practical guidelines that have been proposed, cervical transforaminal epidural injection is still less recommended than cervical interlaminar epidural injection. Objectives: The objective of this study is to introduce Th1-transforaminal epidural injection (Th1- TFEI) through the posterior-lateral approach, compare the injectate spread in Th1-TFEI with that of Th1/2-parasaggital interlaminar epidural injection (Th1/2-pILEI), and clarify the clinical characteristics of Th1-TFEI. Study Design: This research involved a prospective study of 30 patients receiving both Th1-TFEI and Th1/2-pILEI. Methods: Thirty patients with unilateral upper limb pain were enrolled for this prospective study. Th1-TFEI and Th1/2-pILEI were administered on each case in random order under fluoroscopy, and computed tomographic (CT) epidurograms were compared. Changes in circulatory dynamics, presence of Horner’s syndrome, changes in the Numerical Rating Scale (NRS-11), and adverse events were investigated. Results: Patients included 15 men and 15 women and included 24 cases of cervical spine disease and 6 cases with other upper limb pain. The Th1-TFEI group had significantly higher rates of “Th1 root filling” (100%), “ventral spread” (70.0%), and “lateral limitation” (26.7%) compared to the Th1/2-pILEI group. In the Th1-TFEI group, cephalad spread averaged 2.97 vertebral bodies, reaching approximately up to C6. The Th1/2-pILEI group had an average of 4.76 vertebral bodies, approximately up to C4. The 2 groups showed significant differences in cephalad spread. Horner’s syndrome appeared in the Th1-TFEI group at a rate of 56.7%, significantly higher than that in the Th1/2-pILEI group at 17.2%. The presence of Horner’s syndrome showed significant correlations with “ventral spread” and “spread up to C6.” There were no significant differences in NRS-11 improvement and changes in circulatory dynamics between the groups. There were no major complications. Limitations: The components of injectate were standardized; however, the needle gauge numbers were varied. In addition, interpretation of the CT-epidurogram was not blinded. The sample size was small; therefore, multivariate analysis was not possible. Conclusions: CT-epidurogram comparison revealed that Th1/2-pILEI was not localized on the injection side, and there was better dorsal spread – although ventral spread was small. Contrarily, Th1-TFEI was localized on the injection side, and better ventral spread was shown while cephalad spread was limited. We expected the addition of a sympathetic block effect suggested by the Horner’s syndrome as well as the merits of the ventral spread. However, short-term clinical effects were equal to those of Th1/2 pILEI. In future research, we need to standardize the diseases to include and to increase the number of cases to enable evaluation of clinical effectiveness.Key words: Epidural, cervical, transforaminal, interlaminar, fluoroscopy, CT-epidurogram, dorsal, ventral, cephalad, Horner’s syndrome