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ANALGESIA

Sonographic Estimation of Needle Depth for Cervical Epidural Blocks

Soo Hwan Kim, MD^*, Kang Hun Lee, MD^*, Kyung Bong Yoon, MD, PhD^*, Woo Young Park, MD^*, and Duck-Mi Yoon, MD, PhD^*

From the Departments of *Anesthesiology and Pain Medicine, and Anesthesia and Pain Research Institute, Yonsei University Health System, Seoul, Korea.

Address correspondence and reprint requests to Duck-Mi Yoon, MD, PhD, Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, C.P.O. Box 8044, Seoul 120-752, Republic of Korea. Address e-mail to dmyoon{at}yuhs.ac.

Abstract

BACKGROUND: Cervical epidural steroid injections are often used to treat acute and chronic pain syndromes involving the face, neck, and upper extremities. Ultrasound has evolved as a valuable tool for performing neuraxial blocks, providing useful prepuncture information on the structure. Our goal was to evaluate the accuracy and precision of ultrasound by comparing skin to dura distance from ultrasound with the actual skin to epidural depth.

METHODS: We enrolled 50 patients undergoing cervical epidural blocks at the pain clinic. Ultrasound images with transverse and longitudinal median views of the C6/7 area were taken. The epidural needle was inserted, reproducing the direction of the ultrasound beam on the longitudinal median view. Measured distances from skin to dura on each ultrasound view were compared with the actual needle depth. Additionally, we examined ultrasound visibility, the number of puncture attempts, and any complications related to the procedure.

RESULTS: Concordance correlation coefficients between the measured distances on ultrasound and actual needle depth were 0.9272 and 0.9268 on transverse and longitudinal median view, respectively. The cervical epidural block was successfully performed on 48 patients (96%). There were two incidents (4%) of dural puncture. No bloody taps, postprocedure complications, or hemodynamic instability related to cervical epidural blocks occurred.

CONCLUSIONS: Ultrasound provides very accurate information on the skin to dura distance for epidural blocks in the cervical spine. Knowledge of skin to dura distance and a preview of spinal anatomy before puncture can more safely identify the epidural space.