The diagnostic effect of various needle tip positions in selective lumbar nerve blocks: An analysis of 1202 injections

Study Design. Retrospective chart review. Objective. To determine the effect of various needle tip positions on immediate postinjection pain in selective lumbar nerve blocks. Summary of Background Data. To our knowledge, no large study has examined the effect of various needle tip positions within or adjacent to the intervertebral foramen on immediate pain outcome. Methods. A total of 1774 cases of intervertebral lumbar nerve blocks performed by our radiology staff between April 7, 1997 and May 31, 2002, were reviewed. Of the 1774 cases, 1202 met the study criteria (i.e., a singlelevel injection in an adult). The position of the needle tip and degree of immediate postinjection pain relief were examined. Results. The blocks resulted in an average pain reduction of 4.14 U, as graded on a 0-10 ordinate scale (95% confidence interval 3.98-4.30). The degree of pain reduction was not associated with the needle tip position. Conclusions. Our results suggest that precise needle tip position within or adjacent to the intervertebral foramen made no difference on immediate pain reduction. These findings allow the practitioner more freedom in performing an injection. This study does not evaluate the long-term effects of various needle tip positions in selective lumbar nerve blocks.