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Influence of needle position on lumbar segmental nerve root block selectivity
André P Wolff1, Gerbrand J Groen, Oliver H Wilder-Smith
1Pain Centre, Department of Anesthesiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. a.wolff@anes.umcn.nl
Regional Anesthesia and Pain Medicine
|December 2, 2006
Summary
Medial needle placement during segmental nerve root blocks increases epidural spread, potentially affecting accuracy. Electrostimulation is recommended alongside fluoroscopy for precise guidance in chronic low back pain management.
Area of Science:
- Pain Medicine
- Interventional Radiology
- Spinal Procedures
Background:
- Segmental nerve root blocks (SNRBs) are used to diagnose chronic low back pain radiating to the leg.
- Accurate needle placement is crucial, as epidural spread can lead to misinterpretation and affect clinical decisions.
- Previous studies have not systematically analyzed epidural spread in relation to needle position during fluoroscopy-assisted SNRBs.
Purpose of the Study:
- To assess epidural local anesthetic spread during fluoroscopy-assisted SNRBs.
- To investigate the relationship between needle tip location and the extent of epidural spread.
- To evaluate factors influencing the accuracy and selectivity of SNRBs.
Main Methods:
- Prospective observational study of patients undergoing L4, L5, and S1 blocks.
- Fluoroscopy and electrostimulation were used for needle guidance and contrast injection (lidocaine and iohexol mixture).
- X-rays were analyzed to grade epidural spread (0: none, 1: local, 2: to adjacent nerve roots) and assess needle position.
Main Results:
- Epidural spread (Grade 1) occurred in 47% of L4 and 28% of L5 blocks.
- Grade 2 epidural spread was observed in 5% of blocks (L5, S1).
- Medial needle positions within the intervertebral foramen were associated with increased epidural spread (P = .06).
Conclusions:
- Medial needle placement in the intervertebral foramen increases the risk of epidural spread, reducing SNRB selectivity.
- The anatomical variability of the dorsal root ganglion highlights the need for electrostimulation to guide SNRBs.
- Combining fluoroscopy with electrostimulation enhances the accuracy of SNRBs for diagnosing radiating low back pain.
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