Spine. Volume 34(19), 1 September 2009, pp 2008-2013

Clinical Study of Low Back Pain and Radicular Pain Pathways by Using L2 Spinal Nerve Root Infiltration: A Randomized, Controlled, Clinical Trial

Murata, Yasuaki MD, PhD*; Kato, Yoshiharu MD, PhD*; Miyamoto, Kazuhisa MD†; Takahashi, Kazuhisa MD, PhD‡

From the *Department of Orthopedic Surgery, Tokyo Women's Medical University, Tokyo, Japan; †Department of Orthopedic Surgery, Shimishizu National Hospital, Chiba, Japan; and ‡Department of Orthopedic Surgery, School of Medicine, Chiba University, Chiba, Japan.
Acknowledgment date: November 19, 2008. First revision date: February 1, 2009. Second revision date: March 19, 2009. Acceptance date: March 23, 2009.
The legal regulatory status of the device(s)/drug(s) is/are the subject of this manuscript is not applicable in my country.
No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Address correspondence and reprint requests to Yasuaki Murata, MD, PhD, Department of Orthopaedic Surgery, Tokyo Women's Medical University, 8–1 Kawada-cho, Shinjyuku-ku, Tokyo 162-8666, Japan; E-mail: yasuakimurata (at) aol.com

Study Design. Randomized control trial (RCT) for L2 spinal nerve infiltration (L2 block) in clinical cases.

Objectives. To confirm or refute the effect of L2 block using RCT, and to study the pathway of low back pain (LBP) and radicular pain in clinical cases.

Summary of Background Data. It has been reported in animal experiments that one of the main pathways of pain originating from the lumbar spine is the sympathetic trunk through the L2 spinal nerve rootvia sympathetic afferents.

Methods. To evaluate the effectiveness of L2 block, patients who had LBP and were treated with nonsteroidal anti-inflammatory drugs for at least 2 weeks were then randomized to the L2 block or control block groups. The intensities of LBP and radicular pain were measured using visual analog scale and face scale before and at 5 minutes and 7 days after the injection. These values were compared, and the effects of the injections on the pain pathway were studied.

Results. The average visual analog scale scores for LBP before and at 5 minutes and 7 days after the injection were 69, 14, and 44 mm in the L2 block group and 68, 62, and 59 mm in the control block group, respectively. After L2 block, 28 patients reported adequate therapeutic effect at 10 weeks, and the effect lasted for more than 24 weeks in 10 of these patients. After control block, 9 patients reported adequate therapeutic effect at 10 and 24 weeks.

Conclusion. The LBP and radicular pain pathways were likely interrupted by L2 block. An L2 block is useful in reducing LBP due to the disorders of L2 spinal nerve-innervated structures, such as the disc, facet joint, and sacroiliac joint. However, the therapeutic value of an L2 block may be occasionally insufficient to alleviate pain completely because of the short duration of its' effect.

Copyright: © 2009 Lippincott Williams & Wilkins, Inc.