Selective lumbar nerve root blocks (SLNRBs) were reported to be useful in the diagnosis of radiculopathy by Macnab and colleagues (1971) [1]. Furthermore, SLNRB has been found to be effective for the treatment of spinal pain and radiculopathy, and is commonly employed both in the diagnosis and treatment of spinal pain and radiculopathy [2-4]. However, an understanding of the mechanism by which SLNRB achieves analgesia in spinal pain and radiculopathy remains largely unclear. Pfirrmann and colleagues (2001) previously reported that there was no relationship among needle-tip positions, radiating pain, and analgesic effect after comparing the fluoroscopic contrast material distribution, radiating pain, and analgesic effect of SLNRB in combination with steroids. The authors proposed a “safe triangle,” composed of the inferior border of the pedicle, the lateral border of the vertebral body, and the superior border of the nerve root, as the best site for maximising the analgesic effect of SLNRB for the treatment of lumbosacral radicular pain. According to them, SLNRB at this site elicits sufficient analgesia without eliciting radiating pain [5]. This suggests that there is no relationship between the occurrence of radiating pain and the analgesic effect after SLNRB, and that it is not necessary to inject the local anaesthetic agent into the nerve fibres. However, in their study, it is questionable whether the analgesic effect is mainly due to the action of the SLNRB, because of inadequate time to measure the analgesia at 15 minutes and 2 weeks after the SLNRBs. The analgesic effects at 15 minutes and 2 weeks seem to be mainly due to a direct effect of the local anaesthetic agent and to an anti-inflammatory effect of the steroid administered concomitantly, respectively

More Information Please refer the link : Chiba S, et al

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