In a nerve block, a doctor injects the area around the nerve with a numbing medicine, or anesthetic. Lidocaine is the most common anesthetic used. After a nerve block injection, a person will usually rapidly experience numbness with near-complete pain relief. The numbness wears off, though, after several hours.
Some doctors use nerve block injections to try to diagnose what’s causing the back pain. If your doctor does this, you’ll be asked which injection causes the back pain to go away. That nerve may then be chosen for an epidural injection with both steroid and anesthetic medicine. Or the doctor may decide to try another treatment.
Nerve blocks are also performed as anesthesia during surgery or other medical procedures.
Discography Injections to Diagnose Back Pain
In some people back pain is caused by a damaged disc between spinal bones, or vertebrae. In discography, a doctor injects contrast dye into a spinal disc. The doctor then observes the disc on an X-ray video screen. If contrast dye leaks out of the disc, and the person’s usual back pain occurs, the test is considered positive. Clinical studies, however, have not shown that discography is always a helpful test.