Detection of Intravascular Injection During Cervical Transforaminal Epidural Injection: A Comparison of Digital Subtraction Angiography and Real Time Fluoroscopy

Background: Transforaminal epidural injection (TFEI) with local anesthetics and steroids are effective in treating spinal radicular pain. However, inadvertent intravascular injection can lead to severe neurologic complications. To reduce complications of intravascular injection, use of imaging modality, such as real-time fluoroscopy (RTF) or digital subtraction angiography (DSA), has been recommended. DSA is an imaging technique that can clearly visualize the blood vessels from surrounding bones or dense soft tissues by subtracting the pre-contrast image from the image after injecting contrast medium. Objective: In this study, we investigated whether there is a difference between RTF and DSA in the detection of intravascular injection during cervical TFEI. Study Design: Clinical study. Setting: Pain clinic in South Korea. Methods: We prospectively examined 137 cervical TFEIs on 128 patients who have a radiating pain from spinal stenosis and herniated nucleus pulposus. The needle position was confirmed using biplanar fluoroscopy and 2 mL of nonionic contrast medium was injected at the rate of 0.5 mL/sec under RTF. Thirty seconds later, 2 mL of nonionic contrast medium was injected at the rate of 0.5 mL/sec under DSA. Intravascular injection was defined as contrast medium spreading throughout the vascular channel during injection of contrast medium under RTF and DSA. This study is registered in the ClinicalTrials.gov (NCT03040648). Results: The detection rate of intravascular injection in RTF was not statistically different compared to that in DSA (30.7 % vs. 34.3%, P > 0.05). Limitations: We injected 2 mL of contrast medium at the rate of 0.5 mL/sec. Further studies about the ideal injection speed and volume of contrast medium for improvement of detection of intravascular injection during TFEI are needed. This study was a single center study. Therefore, multi-center studies are needed to obtain the high level of evidence. Additionally, the procedural pain physician was not blinded to the type of imaging modality, such as RTF and DSA, to detect intravascular injection. To minimize this confirmation bias and provide homogenous procedural conditions for TFEI, the same procedural physician performed all 137 injections. Conclusions: In this study, there is no significant difference in detection rate of intravascular injection between RTF and DSA during cervical TFEI.