Q: I've given up on trying to get pain relief from my back and leg pain with massage, cold, heat, acupuncture, and exercise. I'm letting the surgeon inject me with whatever it is they use for this type of problem. But I'd like some more information on what they do use and how it's done before I leap. What can you tell me?

A: Epidural injections are a common way to treat painful back problems, especially problems caused by degenerated or herniated discs. But this treatment has also been used in patients with spinal stenosis, postlumbar surgical syndrome, failed back syndrome, and other mechanical causes of low back pain.

When doing an epidural injection, the doctor inserts a needle through the skin so that the tip of the needle is in the epidural space. This space is the area between the bony ring of the spine and the covering of the spine called the dura. The dura is the sac that encloses the spinal fluid and nerves of the spine.

The epidural space is normally filled with fat and blood vessels. Fluid such as the lidocaine and cortisone that can be injected is free to flow up and down the spine and inside the epidural space to coat the nerves that run inside the spinal canal.

These injections control pain by reducing inflammation and swelling. They do not cure any of the diseases they are commonly used for, but can control the symptoms for prolonged periods of time. In some cases, the reduced pain makes it possible for the patient to participate in a physiotherapy program, become more active, and be better able to control the symptoms with a conservative program.

There are two different types of injections and three locations to give them. The injection solution can be a local anesthetic like lidocaine or bupivacaine. Or it could be one of those two numbing agents combined with a steroid (antiinflammatory medication).

There are several openings in the bones that surround the epidural space where a needle can be placed. The injection can be performed by placing the needle in one of three of these openings (caudal, interlaminar, transforaminal). Each of these three types of ESI injections has advantages.

In a recent study comparing injection of local anesthetic with combined analgesic and steroid, researchers found that epidural injections (more commonly known as epidural steroid injections or ESI) were superior to analgesic injections alone. This study only looked at patients with pain from disc herniations not any of the many other spinal problems injections are used for. And only caudal injections were used so there's still a need for further studies to evaluate (and compare) results among all three injection sites.

For patients who do not want steroid injections, injection of a local anesthetic can yield good results, too. They should be told that the results may not last as long as with steroid injection and that more injections may be required. Even so, epidural injection of an anesthetic is an acceptable treatment approach.

This information may help you understand the proposed procedure and make it possible to discuss the intended treatment for you. For more information on the treatment of chronic low back pain with epidural (steroid) injections, see A Patient's Guide to Epidural Steroid Injection.

Reference: Laxmaiah Manchikanti, MD, et al. A Randomized, Controlled, Double-Blind Trial of Fluoroscopic Caudal Epidural Injections in the Treatment of Lumbar Disc Herniation and Radiculitis. In Spine. November 1, 2011. Vol. 36. No. 23. Pp. 1897-1905.