Influence of needle-tip position on the incidence of immediate complications in 2,217 selective lumbar nerve root blocks.

BACKGROUND CONTEXT: Selective lumbar nerve blocks (SLNBs) are a popular, minimally invasive treatment and diagnostic tool for lumbar radiculopathy. It is therefore relevant to determine the complication rate for SLNBs, as well as examine the association between needle-tip position and complication rates in order to improve safety.

PURPOSE: The purposes of the present study are to determine the overall rate of immediate, postprocedural complications in a large cohort of patients who received SLNBs and determine if certain needle-tip positions are less likely to cause complications. To our knowledge, this is the first paper to examine the relationship between needle-tip position and complications.

STUDY DESIGN: A large retrospective cohort was assembled from patients who had undergone a SLNB. We determined the overall immediate complication rate for all injections. In addition, all patients who received only a single injection were compiled into another cohort, and needle-tip position was determined. The complication rate was determined for each needle-tip position.

PATIENT SAMPLE: All adult patients who underwent a SLNB in a single radiology department from April 1, 1997 to May 31, 2002.

OUTCOME MEASURES: Patients were observed for 15-30 minutes after their procedure, then interviewed about any self-reported weakness, light-headedness, increase in pain from the preprocedural levels, or development of new pain. Their postprocedural pain was then rated on the Visual Analogue Scale. The radiologic notes from each examination were reviewed for incidence of these, or any other, complications.

METHODS: SLNBs were performed as they would be in the normal course of care, using fluoroscopic guidance and methodology established by a single radiologist overseeing the procedures. The radiologist's record of each visit was examined for note of immediate, postprocedural complications. The radiographs from the patients who received a single injection during their visit were examined to determine the position of the needle tip during the procedure. The needle-tip positions from the "Complications" and "No Complications" single injection cohorts were compared to determine if certain needle-tip positions cause less complications than others.

RESULTS: Minor complications were encountered in 98 of the 1,777 total patient visits, for an overall complication rate of 5.5%. All complications were transient, and no patient suffered lasting harm. There were 1,232 procedures in which the patient received a single injection, and a minor complication was encountered in 62 of these visits. The complication rate approached 5% for all needle-tip positions, which is not statistically different from the overall complication rate. However, there was an increased likelihood of complications in patients undergoing a multiple injection procedure vs. those who had only one injection.

CONCLUSIONS: Our results suggest that SLNBs performed with fluoroscopic guidance have a low incidence of complications. All of our complications were minor. The specific needle-tip position within or adjacent to the lumbar neural foramen does not appear to be associated with the incidence of complications.