Contralateral Oblique Research Articles

FACTFINDERS FOR PATIENT SAFETY: Minimizing risks with cervical epidural injections

This series of FactFinders presents a brief summary of the evidence and outlines recommendations to minimize risks associated with cervical epidural injections.Evidence in support of the following facts is presented.Minimizing Risks with Cervical Interlaminar Epidural Steroid Injections – 1) CILESIs should be performed at C6-C7 or below, with C7-T1 as the preferred access point due to the more generous dorsal epidural space at this level compared to the more cephalad interlaminar segments. This reduces the risk of the minor complication of dural puncture and the major complication of spinal cord injury due to inadvertent needle placement. 2) LF gaps are most prevalent in the midline cervical spine. This can result in diminished tactile feedback with loss of resistance (LOR), increasing the risk for inadvertent dural puncture or spinal cord injury. Based on current evidence, needle placement in the paramedian portion of the interlaminar space is safest to avoid LF gaps. 3) An optimal AP trajectory view and the physician's ability to discern engagement in the LF and subsequent LOR are crucial. Confirmation of minimal needle insertion depth relative to the ventral margin of the lamina with either a lateral or contralateral oblique (CLO) safety view is critical to minimize the risk of inadvertently inserting the needle too ventral. 4) There have been closed claims and case reports of patients who have suffered catastrophic neurologic injuries while receiving CILESIs under deep sedation. If sedation is administered, the least amount necessary should be utilized to ensure the patient can provide verbal feedback during the procedure. 5) CILESIs are an elective procedure; therefore, necessity and likelihood of benefit must be foremost considerations. Current guidelines recommend holding ACAP therapy before CILESIs due to the potentially catastrophic complications associated with epidural hematoma (EH) formation. However, there is also a risk of severe systemic complications with ceasing ACAP in specific clinical scenarios. The treating physician is obligated to determine if the procedure is indicated and can ultimately decide to delay the intervention or not perform the procedure if the benefit does not outweigh the risks.Minimizing Risks with Cervical Transforaminal Epidural Steroid Injections – the Role of Preprocedural Review of Advanced Imaging -- Variations in vascular anatomy may warrant a modified approach to CTFESI. Preprocedural review of cross-sectional imaging can provide critical information for safe injection angle planning specific to individual patients and may help to decrease the risk of unintended vascular events with potentially catastrophic outcomes.Safety of Multi-level or Bilateral Fluoroscopically-Guided Cervical Transforaminal Epidural Steroid Injections -- Safe performance of a CTFESI procedure requires the ability to detect inadvertent arterial injection. Contrast medium placed into the epidural space and/or along the exiting spinal nerves during an initial CTFESI may obscure the detection of inadvertent cannulation of a radiculomedullary artery by a subsequent CTFESI. While no available literature directly addresses the potential risk that exists with a multi-level or bilateral CTFESI, caution is still warranted.

Subdural Contrast Spread in the Contralateral Oblique View During Epidural Steroid Injection

Subdural Contrast Spread in the Contralateral Oblique View During Epidural Steroid Injection

The contralateral oblique fluoroscopic view is associated with a lower incidence of postdural puncture headache in patients undergoing percutaneous spinal cord stimulation.

Spinal cord stimulation (SCS) is a minimally invasive therapy that is increasingly used to treat refractory neuropathic pain. Although this technique has a low incidence of serious long-term adverse sequelae, the risk of complications such as inadvertent dural puncture remains. The goal of this article was to determine the impact of the contralateral oblique (CLO) fluoroscopic view incidence of postdural puncture headache (PDPH) during spinal cord stimulator implantation as compared to lateral fluoroscopic view. This was a single academic institution retrospective analysis of electronic medical records spanning an approximate 20-year time period. Operative and postoperative notes were reviewed for details on dural puncture, including technique and spinal level of access, the development of a PDPH, and subsequent management. Over nearly two decades, a total of 1637 leads inserted resulted in 5 PDPH that were refractory to conservative measures but responded to epidural blood patch without long-term complications. The incidence of PDPH per lead insertion utilizing loss of resistance and lateral fluoroscopic guidance was 0.8% (4/489). However, adoption of CLO guidance was associated with a lower rate of PDPH at 0.08% (1/1148), p < 0.02. The incorporation of the CLO view to guide epidural needle placement can decrease the odds of a PDPH during percutaneous SCS procedures. This study further provides real-world data supporting the potential enhanced accuracy of epidural needle placement in order to avoid unintentional puncture or trauma to deeper spinal anatomic structures.

ID: 216501 Subdural Contrast Spread in the Contralateral Oblique View During Epidural Steroid Injection

Introduction/Description: For accessing the cervical epidural space, the contralateral oblique (CLO) view under fluoroscopy at 50 degrees (CLO50) has been described as a safe and effective view for obtaining epidural access with some studies suggesting it is superior to the lateral and anteroposterior (AP) views for correct needle tip placement [1]. Because false loss of resistance can still occur using this approach, contrast medium needs to be injected prior to medication administration to ensure correct placement. It is important to recognize spread patterns within the meningeal layers to distinguish between proper placement into the epidural space and unintended spread into the subdural or intrathecal space.

Contralateral oblique view can prevent dural puncture in fluoroscopy-guided cervical epidural access: a prospective observational study

IntroductionAlthough the contralateral oblique (CLO) view at 50°±5° is clinically useful for cervical epidural access, no previous studies have confirmed its safety. This prospective observational study was conducted to assess...

Comparison of the contralateral oblique view with the lateral view for mid-thoracic epidural access under fluoroscopic guidance: a randomized controlled trial

BackgroundThe fluoroscopic-guided epidural access is occasionally challenging; therefore, the contralateral oblique (CLO) view has emerged as an alternative approach. The CLO view appears to be optimal for mid-thoracic epidural access;...

Contralateral and Lateral Views: Analysis of the Technical Aspects of Spinal Cord Stimulator Lead Insertion.

BackgroundSpinal cord stimulation (SCS) is an established treatment modality for neuropathic pain. The critical part of this technique is safe access to the epidural space for lead placement. There have been innovations in radiological views, improving access to the epidural space.ObjectivesThis study analyzes the adoption of these technical advantages in daily practiceMethodsWe conducted a survey of members in the Spine Intervention Society and American Society of Regional Anesthesia in regard to the practice patterns in SCS therapy. Here we present our findings regarding the use of contralateral oblique (CLO) and lateral views as well direct upper thoracic or cervicothoracic access for SCS lead insertionResultsA total of 195 unique responses were received between March 20, 2020 and June 26, 2020. Forty-five percent of respondents “always used” the lateral view technique while 15% “always used” CLO view for SCS lead insertion. Overall, sixty-five percent of respondents used the CLO view with varying frequency. Cervical and upper thoracic approach for cervical SCS lead placement is always or often used by 66.8% of the respondents.ConclusionsA depth view (CLO or lateral) is always used by only 45 - 60% of the respondents and CLO view has been rapidly adopted in clinical practice for SCS lead insertion. Direct cervicothoracic and upper thoracic is the preferred approach for cervical lead placement by the majority.

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

BackgroundCervical 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...

Intrathecal Contrast Spread Pattern in the Lumbar Spine in Contralateral Oblique View.

The lumbar epidural space is an important potential space that is accessed for several therapeutic interventions. Accuracy and confirmation of the needle tip being in the correct space are paramount not only for optimal therapeutic benefit but also to avoid potential harm to the patient. Although it is vital to be able to recognize contrast spread patterns in the epidural space as described by Gill et al. [1], it is just as important to be able to recognize contrast spread patterns in the intrathecal space during accidental dural puncture to be able to correct needle trajectory/depth and avoid inadvertent intrathecal injection. The contralateral oblique (CLO) view has been described as a superior view when compared to the lateral view for correct needle tip placement by Gill et al., specifically at 45 degrees (CLO 45) when working at the lumbar level [2]. Similarly, there are instances where...

Novel method for modified interlaminar approach using contralateral oblique view: A technical suggestion.

A modified interlaminar (MIL) approach has been proposed for improved accessibility to the target epidural space. However, even with fluoroscopic guidance, uncertainty about the distance between the needle tip and the epidural space can remain. Using the contralateral oblique (CLO) view, determination of the epidural space can be easier with clearer identification of the interlaminar opening. We inserted the needle at the midpoint of the interlaminar opening on the fluoroscopic anteroposterior (AP) view and made the needle oriented toward the pedicle of the target side. Then, CLO view was created by rotating the intensifier approximately 45 degrees to the contralateral side of the target. Through the CLO view, the ventral interlaminar line (VILL) was confirmed and the needle was able to enter the epidural space more easily. The medical records of 29 patients who were conducted MIL approach using CLO view were retrospectively analyzed to evaluate the effectiveness and safety of this procedure. The accessibility to the ventral epidural space was 93.1%. There was no procedure-related complication. Using CLO view, uncertainty can be reduced during the MIL approach, which in turn shortens procedure time and improves safety.

Evaluation of Contralateral Oblique and Lateral Views for Mid-Thoracic Epidural Access: A Prospective Observational Study

BACKGROUND: The mid-thoracic region has been known to be the most difficult area when accessing epidural space despite using fluoroscopy. Contralateral oblique (CLO) view has been considered for use; however, it has not been evaluated in the mid-thoracic region. OBJECTIVE: To evaluate the CLO view for mid-thoracic epidural access (TEA). STUDY DESIGN: A prospective observational study. SETTING: The study took place at a single pain clinic within a tertiary medical center in Seoul, Republic of Korea. METHODS: A total of 30 patients participated in this study. After securing the mid-thoracic (T4–8) epidural space, fluoroscopic images were obtained. The needle tip location relative to the ventral interlaminar line (VILL), and the needle tip and laminar visualization were measured and analyzed on the CLO views at 40, 50, 60 degrees, and measured angle, and the lateral view. RESULTS: The needle tip was clearly visualized in all CLO views, compared with the lateral view (100% vs. 36.7%, P &lt; 0.001). The visualization of the laminar margin and the needle tip location on (or just anterior to) VILL using the CLO measured angle were significantly clearer compared with those in the CLO view at 40 and 50 degrees and the lateral view (laminar margin: 40˚, 56.7% vs. 3.3%, P &lt; 0.001; 50˚, 56.7% vs. 26.7%, P = 0.012; 90˚, 56.7% vs. 26.7%, P = 0.035; needle tip location: 40˚, 96.7% vs. 26.7%, P &lt; 0.001; 50˚, 96.7% vs. 63.3%, P = 0.002; 90˚, 96.7% vs. 66.7%, P = 0.012). There was no difference in these values between the CLO view at 60 degrees and CLO measured angle. LIMITATIONS: Subjective and ambiguous criteria of evaluation may induce bias despite final measured values based on the consensus of an independent investigator. CONCLUSION: A CLO view at 60 degrees and CLO measured angle view can provide clearer visualization and more consistent needle tip location than the lateral and other CLO angle views for mid-TEA. A CLO view at 60 degrees and CLO measured angle views could be used to identify the needle location and achieve success in mid-TEA. KEY WORD: Chronic pain, contralateral oblique view, fluoroscopy, lateral view, mid-thoracic, pain management, epidural analgesia, ventral interlaminar line

Lumbar Epidural Contrast Spread Patterns for the Interlaminar Approach: Three-Dimensional Analysis Using Antero-Posterior, Lateral, and Contralateral Oblique Views.

To describe and analyze lumbar epidural contrast spread patterns in antero-posterior (AP), lateral, and contralateral oblique (CLO) views. Lumbar epidural contrast spread patterns after interlaminar injection were prospectively collected in AP, lateral, and several CLO views and analyzed for multiple variables; three-dimensional mapping was also performed. Epidural contrast patterns were prospectively analyzed in 28 subjects. The median volume of contrast injected was 2 mL; the AP view was more sensitive than the lateral view to detect foraminal uptake (13/28, 46%, 95% confidence interval [CI] = 27-66%, vs 7/28, 25%, 95% CI = 11-45% subjects). CLO view demonstrated the most consistent location for epidural contrast spread, with contrast contacting the ventral laminar margin in 28/28 (100%, 95% CI = 87-100%) patients. The most common location of contrast spread in the lateral view was at the facet joint lucency, with only 8/28 (29%, 95% CI = 13%-49%) subjects showing contrast contacting the spinolaminar junction. Lateral view was more sensitive than the CLO view in ventral epidural contrast spread detection. The extent and distribution of the spread did not bear any relationship to the volume injected or to the needle location in AP view. CLO view provides the most consistent landmark for lumbar epidural contrast spread, and lateral view is most suited to confirming ventral epidural spread. The AP view may be the most optimal for determining target access when considering access to the dorsal root ganglia; in an individual patient, the volume injected and needle location in AP view do not reliably predict target access. The volume to be injected and the need to re-access or obtain multisite access must be prospectively determined, based upon observation of the spread.

DEPTH ASSESSMENT USING CONTRALATERAL OBLIQUE VIEW DURING CERVICAL INTERLAMINAR EPIDURAL STEROID INJECTIONS

Background: Recent literature has demonstrated that the contralateral oblique (CLO) view provides a more reliable angle in determining needle depth when compared to the lateral view during cervical interlaminar injections. Despite the utilization of CLO safety views, contrast patterns, and loss-of-resistance techniques, inherent risk of injury still remains. Additional safety measures must be assessed to provide clinicians with further safeguards to prevent procedural complications. Objective: The purpose of our study is to provide a reliable method of gauging needle depth insertion during cervical interlaminar injections by comparing the distance from the skin to the epidural space when measured on magnetic resonance imaging (MRI) and when measured intraoperatively. Methods: The study sample included 45 patients with cervical radiculopathy or cervical spinal stenosis. The distance from the skin to the epidural space was measured on cervical spine MRI and with the spinal needle intraoperatively. Primary analysis included the correlation between these distances, and whether differences in depth were influenced by injection level, needle tip location, or body mass index (BMI). Results: A significant correlation (r = .975, P &lt; .001) with an average difference of .03 mm (standard deviation, 2.99 mm) was found between MRI and procedural measurements. Neither injection level nor BMI had a significant influence on the difference in depth. Conclusion: When combined with traditional safety techniques, obtaining preprocedural MRI depth measurements can provide a reliable method in predicting the true needle depth to safely enter the epidural space. Because the majority of patients undergoing interlaminar cervical epidural steroid injections will have already obtained MRI, measuring the distance preprocedurally is a simple and practical method for physicians to implement. Key words: Cervical, fluoroscopy, radiculopathy, injection, contra-lateral oblique, contrast, safety, complications, spinal stenosis, radiation, interlaminar

Iliac artery deformation during EVAR.

Objectives To quantify the deformation of the common iliac artery caused by stiff guide wires and delivery systems during abdominal endovascular aortic repair (EVAR). Methods Twenty-two patients treated with abdominal EVAR were included. The following three image data-sets were acquired for each patient: (1) a preoperative computed tomography angiography (CTA), (2) an intraoperative contrast-enhanced cone beam CT (CBCT) obtained after the main trunk of the bifurcated stent graft was released and both iliac limbs were engaged with stiff guide wires, and (3) the first postoperative CTA. These data-sets were merged and compared in an image analysis work station. The length and the tortuosity index of the common iliac artery, the Euclidian displacement of the aortic and the iliac bifurcations, and the optimal C-arm angulation for projection of the iliac bifurcation were computed. Results The common iliac artery was on average 6.4 mm shorter ( p &lt; 0.001) and tortuosity index was lower ( p = 0.003) in the intraoperative images compared to preoperative. Some of the foreshortening was reversed postoperatively, remaining mean length difference was 2.9 mm ( p = 0.007) compared to preoperative. Intraoperatively, the aortic bifurcation was mostly displaced in a cranial direction (100%) and the iliac bifurcation in a ventral direction (93%). The optimal lateral C-arm angulation for projection of the iliac bifurcation changed. Anterior contralateral angle increased from median 42° (IQR, 27–63) in the preoperative CTA to 62 (49–74) in the intraoperative CBCT ( p = 0.02). Optimal cranio-caudal angulation did not change. Conclusion Stiff guide wires and delivery systems cause significant deformation of the common iliac arteries during EVAR. The aortic bifurcation is more cranial, the common iliac arteries are shorter, and optimal C-arm angulation is more contralateral oblique when the iliac limbs are to be deployed compared to baseline measurements from preoperative CTA. This affects image fusion accuracy and stent graft selection.

The Utility of Determining the Fluoroscopic Contralateral Oblique Angle Measurement During Cervical Interlaminar Epidural Steroid Injections for Use in Repeat Injections.

The Utility of Determining the Fluoroscopic Contralateral Oblique Angle Measurement During Cervical Interlaminar Epidural Steroid Injections for Use in Repeat Injections.

DIAGRAMMATIC ANALYSIS OF SUBARACHNOID CONTRAST SPREAD IN THE CONTRALATERAL OBLIQUE VIEW: A TECHNICAL REPORT

Interlaminar epidural steroid injections are commonly used in clinical practice for the relief of low back pain. Reliable deposition of medication in the epidural space is important in producing significant results. Pathological conditions, including vertebral osteoarthritis, degenerative disc disease, and spinal stenosis, are frequently treated with epidural steroid injections. Associated degenerative features such as ligamentum flavum hypertrophy, facet joint hypertrophy, and osteophyte formation can lead to significant alterations in the anatomy of the epidural space. Epidurograms, prior to steroid injection, aid the physician in identifying the epidural space, as a false loss of resistance can occur. Extradural, subdural, intradural, and subarachnoid contrast spread has been demonstrated in the anteroposterior and lateral views; but, has not previously been demonstrated in the contralateral oblique (CLO) view. This technical report is the first to demonstrate concomitant epidural and subarachnoid spread in the contralateral oblique view after inadvertent low volume subarachnoid injection, as might happen in clinical practice. In this technical report, we demonstrate both epidural and subarachnoid contrast spread in the contralateral oblique view and compare it to the anteroposterior view. In an oblique view, epidural contrast spread is observed to approximate the ventral margin of the superior aspect of the lamina while subarachnoid contrast spread has a distinct demarcation at the ventral laminar margin. In an anteroposterior view, epidural spread is confirmed by spread of the dye along the nerve roots and beyond the margins of the pedicles. The CLO view provides an accurate and consistent visualization of the epidural space; irrespective of the obliquity, epidural contrast is observed to approximate the ventral margin of the superior aspect of the lamina. In the CLO view, if contrast spread does not approximate the lamina, then intrathecal injection must be considered. Key words: Epidural steroid injection, epidurogram, epidural spread, subarachnoid injection, intrathecal spread, fluoroscopy, contralateral oblique view

NEEDLE TIP DEPTH ASSESSMENT ON FORAMINAL OBLIQUE FLUOROSCOPIC VIEWS DURING CERVICAL RADIOFREQUENCY NEUROTOMY. A TECHNICAL NOTE

Background: Precise needle tip visualization using fluoroscopy is critical to avoid injury to nearby neurovascular structures during cervical radiofrequency neurotomy (RFN). The contralateral oblique (CLO) view has been shown to be superior to the lateral view for needle tip visualization during cervical interlaminar epidural injection (CESI). It has been demonstrated that increasing the angle of obliquity during CESI causes the needle tip to appear to move dorsal and superficial on contralateral oblique views. Needle tip visualization for cervical RFN has been described using a foraminal oblique (FO) view, but the technique and effect of angle on needle tip depth have not been studied. Objective: To analyze how the needle tip depth changes with varying oblique angles of FO views during cervical RFN. Methods: Fluoroscopic views during cervical RFN between lateral and 50 degrees FO in a single subject were analyzed. Results: The needle tip appears to move ventral and deeper with increasing angle of obliquity with respect to the lamina. Conclusion: Contrary to the phenomenon noticed with contralateral oblique views in CESI, in this case the needle tip appears to move ventral and deeper with increasing angle of obliquity on foraminal oblique views during cervical RFN. It becomes crucial for practitioners to understand that during cervical RFN, with inadequate foraminal oblique angle, needle tip looks artificially superficial, which in turn may cause one to advance the needle to a dangerous depth. Limitation: This is an observational study in a single subject; hence further larger studies are needed to confirm the findings in this technical report. Key words: contralateral oblique, needle depth assessment, cervical radiofrequency neurotomy, cervical radiofrequency ablation, foraminal oblique, fluoroscopy views, fluoroscopy angles

Reliability and Safety of Contra-Lateral Oblique View for Interlaminar Epidural Needle Placement

Cord trauma is a risk with a cervical and thoracic interlaminar epidural approach to the epidural space. Intermittent lateral fluoroscopic imaging to detect needle depth is often cumbersome and may be difficult to interpret. In comparison, the contra-lateral oblique (CLO) fluoroscopic view is efficient and easy to interpret. However, the in vivo reliability and safety of this technique has not been formally investigated.The senior author collected fluoroscopic images on 278 consecutive patients undergoing an interlaminar epidural block at the T1-T2 level performed using a 17 gauge Tuohy needle. Before catheter placement, anterior-posterior (AP) and CLO fluoroscopic images were saved with the needle at the ligamentum flavum and the needle just through the ligamentum flavum.We randomly selected the images of 40 cases that included the paired CLO images (total 80 images) documenting the views at and through the ligamentum flavum. Three interventionalists were asked to review, in a blinded fashion, the randomly selected, paired CLO images and to score each image, recording whether the 17 gauge needle was in or out of the epidural space to determine the accuracy and reliability of this technique.There was a 97.5%, 95%, and 93.8% agreement between each reviewing physician and the senior author resulting in a correlation using the Kappa statistic value of 0.950, 0.875, and 0.874, respectively (P < 0.001). The 3 reviewing physicians disagreed with the senior author's correct answer in 2.5%, 5%, and 6.2%, respectively, however, the disagreement occurred primarily because of poor image quality. Agreement between the 3 reviewing physicians was 93.8%, 96.3%, and 90%, with a Kappa value of 0.875, 0.924, and 0.799, respectively (P < 0.001). There was 100% technical success in the 278 case series without "wet taps," provocation of pain during entry, or any other immediate post procedural complication.We conclude the CLO view provides an efficient and reliable method to visualize needle tip depth in relation to the epidural space. The close inter-observer agreement was possible with minimal physician instruction.Key words: Cervical interlaminar, cervical epidural, contra-lateral oblique, fluoroscopic imaging.

Optimal Angle of Contralateral Oblique View in Cervical Interlaminar Epidural Injection Depending on the Needle Tip Position

Chronic neck and upper extremity pain associated with cervical origin is common, and cervical interlaminar epidural steroid injections (CILESIs) are frequently used to manage the symptoms of cervical spinal disorders. However, CILESIs are associated with risks such as dural puncture and cord injury. We aimed to determine the optimal needle tip visualization, in order to minimize CILESIs-induced complications. Retrospective observational study. The single center study in Seoul, Republic of Korea. Participants were 312 adults with neck or upper extremity pain caused by cervical lesion such as cervical herniated nucleus pulposus (HNPs). They underwent magnetic resonance imaging (MRI). Patients with severe cervical spinal stenosis, prior posterior cervical spine surgery, or other anatomical abnormalities of the vertebral laminae were excluded from the study. By using axial T2-weighted spin-echo MRI, we defined the area between the spinous processes as the anterior posterior zone 1 (APZ1), and the area lateral to the spinous processes as the anterior posterior zone 2 (APZ2). Line 1 was drawn along the ventral margin of lamina that confined APZ1, and line 2 was similarly drawn in order to define APZ2. The angles between the midsagittal line and lines 1 and 2 were defined as angle 1 and angle 2, respectively. Angles were measured at the C5-6, C6-7, and C7-T1 levels, on both right and left sides at each level. Angle 1 values (in degrees) at right C5-6, left C5-6, right C6-7, left C6-7, right C7-T1, and left C7-T1 were 62.54 ± 10.52, 64.34 ± 9.86, 62.03 ± 10.27, 62.87 ± 10.64, 61.64 ± 11.0, and 62.58 ± 10.83, respectively. Angle 2 values at right C5-6, left C5-6, right C6-7, left C6-7, right C7-T1, and left C7-T1 were 50.44 ± 6.84, 50.77 ± 7.00, 49.15 ± 6.07, 49.89 ± 6.45, 50.84 ± 6.68, and 50.24 ± 6.60, respectively. There were significant differences between angles 1 and 2 at each level. This study is a retrospective review and did not employ controls, blinding, or randomization. Additionally, the optimal CLO angles for CILESIs and cervicothoracic interlaminar epidural steroid injections (CTILESIs) have not been assessed in clinical studies. Another limitation is that we divided lamina into only APZ1 and APZ2. During CILESIs, a contralateral oblique (CLO) view at 60 degrees is superior to other angles for visualizing the epidural space when the needle tip is placed in the interlaminar space and within the spinous processes margin. When the needle tip is placed in the interlaminar space and lateral to the spinous processes, a CLO view at 50 degrees is most appropriate.Institutional Review Board (IRB) approval number: S2016-0390-0001Key words: Chronic neck pain, chronic upper extremity pain, cervical epidural injections, cervical interlaminar steroid injections, steroid, needle tip position, needle tip visualization, fluoroscopy, complication, contralateral oblique view.

Cervical Epidural Contrast Spread Patterns in Fluoroscopic Antero-Posterior, Lateral, and Contralateral Oblique View: A Three-Dimensional Analysis.

To describe and to analyze cervical epidural contrast patterns seen in antero-posterior (AP), contralateral oblique (CLO), and lateral view. To identify factors that might help in predicting contrast distribution pattern and extent. Spread of contrast in the cervical epidural space was prospectively studied in AP, lateral, and three CLO views. CLO view showed contrast spread of variable thickness with its posterior margin overlying the ventral interlaminar line (VILL). In the lateral view, the spread was also of variable thickness, but the posterior margin of the contrast lay on the spinolaminar line in only 10 of 24 patients. Ventral contrast spread was not visualized in any patient. In the AP view, bilateral spread was seen in 14 of 24 subjects, and nerve root spread was seen in 16 of 24 subjects. No association of the pattern of spread or dispersion was seen to patient age, volume injected, or needle location. The CLO view provides a consistent radiological landmark for the posterior margin of contrast in the dorsal epidural space; the lateral view fails to provide such a consistent landmark. The thickness of the spread is variable, both in the CLO and in the lateral view. Thick spread extending into the foramen in the CLO view and over the articular pillars in the lateral view is frequent and should not be misconstrued as subdural or intrathecal spread. In contradistinction to previous studies, true ventral spread was not seen in any patient. When using low volumes, contrast spread is independent of patient age, volume injected, or needle tip location in the AP view.