Clinical study of low back pain and radicular pain pathways by using l2 spinal nerve root infiltration: a randomized, controlled, clinical trial.

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.