Transforaminal epidural injection (modern nomenclature) or a selective nerve root block (old nomenclature) consists of injection of contrast, local anesthetic, or other substances around spinal nerves under fluoroscopy. These are used for diagnostic as well as therapeutic purpose. The reported sensitivity of a diagnostic selective nerve root block ranges from 45% to 100%. Therapeutically it is more effective than simple Lumber or Caudal epidural steroid injection as we are installing the drug more anteriorly right at the target. Drug dose is also much less. (10-20mg vs. 40-80 mg in lumber/caudal epidural.) If there is epidural scar like in failed back surgery syndrome it is the only root to inject epidural steroids.