Selective nerve root block (SNRB) is a procedure designed to provide both diagnostic and therapeutic information about pain emanating from a radicular nerve. Some practitioners also call this procedure a selective epidural.
Under live and intermittent fluoroscopy a needle is placed adjacent to the target nerve as it exits the spine through the corresponding foramen. After placement verification using radiopaque contrast, a small amount of medication is then placed along the course of the nerve. For diagnostic purposes the medication used is a short acting local anesthetic. If therapeutic effect is also desired, a small amount of steroid may be injected concurrently to decrease inflammation and provide long-term pain relief.
An initial report is obtained from the patient concerning the change in their pain post-injection compared to pre-injection. A second report is obtained 1 – 2 weeks later.
SNRB is useful diagnostically when there is uncertainty about the involvement of a specific nerve root in the cause of spine and extremity pain.