I had a nerve block last year that was supposed to put a stop to my chronic back and leg pain. The procedure itself was very painful. But once the nerve was numb, I felt much better. Now I need another injection. The surgeon is going to use ultrasound to guide the needle. This is supposed to be a pain free process. Is it really?

According to a recent study involving 78 patients who had an ultrasound-guided nerve block for L5 radicular syndrome, the procedure is painless. They all reported a tapping sensation but no pain and no muscle contraction. L5 radicular syndrome refers to pressure on the spinal nerve root located at the bottom of the lumbar spine causing back and buttock and/or leg pain.

The reason for the difference in patient response between X-ray and ultrasound-guided techniques has to do with the way the procedure is done. The X-ray guided approach uses a contrast dye that is injected into the nerve. The dye makes the nerve visible on X-rays. This allows the surgeon to confirm correct placement of the needle delivering the numbing agent. The ultrasound method uses a very low intensity electrical stimulation. The electrical pulses create the tapping sensation when the needle is close to (but not inside) the nerve.

Not only is the ultrasound-guided procedure more comfortable for the patient, it is safer. That’s because once the nerve has been located, a numbing solution is injected around the nerve to block pain messages from traveling to the spinal cord up to the brain. The nerve isn’t punctured, which then prevents further damage to the already compromised nerve tissue. And the patient is exposed to less radiation, another bonus of the ultrasound method.