A nerve root block is an injection of local anesthetic (numbing medicine) and steroid injected under X-ray guidance into the area where the nerve exits the spinal column. A nerve block injection is used to both diagnose and treat an inflamed spinal nerve. A medication, typically, an anesthetic or anesthetic with steroid is administered near the spinal nerve as it exits the intervertebral foramen (bony opening between adjacent vertebrae). The medication reduces inflammation and numbs the pain transmitted by the nerve.
When used for treatment purposes, steroids are usually mixed with anesthetics or used alone in selective nerve root block injections. Steroids in nerve blocks work by a combination of the following mechanisms1
Reduce inflammation that causes neural irritation and pain Block specific fibers (C fibers) within the nerve that results in lesser pain transmitted to the brain Decreasing pain transmission
It is done under local anesthesia. Patient is completely awake and talking to the doctor.