Variations in selective nerve root block technique

Much literature reports on selective nerve root blocks (SNRBs) in cases of lumbosacral radiculopathy. Unfortunately, authors only inconsistently reveal the exact needle tip position relative to the causative pathology at the time of injection. Different injection sites may provide different symptomatic benefits. We investigated the variation in injection techniques of practitioners working in the UK.

A clinical scenario was devised depicting a patient with radiculopathy secondary to an L4/5 vertebral disc prolapse. Participants were questioned on their chosen management of this patient, focusing particularly on SNRB technique. Questionnaires were sent to spinal surgeons, pain management specialists and musculoskeletal radiologists.

A total of 100 responses were detailed enough for inclusion. The majority (83%) of respondents reported they would inject local anaesthetic and steroids, 4% would inject local anaesthetic alone and 13% would inject a different substance. Over half (53%) would target the L5 nerve root, 26% the L4 nerve root, 12% the prolapsed disc itself and 9% two separate vertebral levels. Variation was also noted in needle tip location relative to the neural sheath.

When treating lumbar radiculopathy, there are apparent variations in the use and positioning of SNRBs for a given level of disc pathology. Needle tip position may have a direct influence on clinical outcome following SNRBs. Caution is therefore required when considering the validity of previously published studies investigating SNRBs and different injectates.