Selective nerve root blocks as predictors of surgical outcome: Fact or fiction?

The hypothesis that delivering local anesthetic to a single nerve root will selectively and specifically block only that nerve and will provide accurate information that could predict surgical success has been, to date, based mainly on clinical assumption without many adequately performed trials proving their validity. Many factors have been identified to be a source of bias in the response to these injections, including anatomical variations and technical/procedural differences. Review of the available data on selective nerve root blocks as predictors of surgical outcomes demonstrates that these blocks have high sensitivity, low specificity, and strong negative-predictive value and therefore should be considered as tools that dissuade (not persuade) surgical resolution.