An epidural steroid injection is a cortisone injection used to treat inflammation around the spine. Cortisone is a type of steroid that is produced naturally by a gland in your body called the adrenal gland. Cortisone is released from the adrenal gland when your body is under stress. Natural cortisone is released into the blood stream and is relatively short-acting.
Injected cortisone is synthetically produced and has many different trade names (Celestone, Kenalog, etc.), but is closely related to your body's own cortisone. The most significant differences are that synthetic cortisone is not injected into the blood stream, but into a particular area of inflammation. Also, the synthetic cortisone is designed to act more potently and for a longer period of time (days instead of minutes).
An epidural steroid injection places this powerful anti-inflammatory medication directly around the spinal nerves. Traditionally epidural injections were administered without any special equipment, by inserting the needle by feel in the area around the spinal nerves. More recently epidural injections have been administered with the aid of imaging tools to allow your physician to see the needle going to the proper location. Either real-time x-ray, called fluoroscopy, or CT scan can be used to 'watch' the needle deliver the medication to the proper location. Recent studies have demonstrated that these injections given with imaging guidance are more accurate and more successful than injections given without imaging guidance. In fact, the Choosing Wisely campaign to recommend best medical practices, advised patients to have epidural injections administered with this type of imaging guidance rather than done without imaging.
Epidural steroid injections may be given by many types of physicians, including anesthesiologists, orthopedic surgeons, neurologists, interventional radiologists, pain management specialists, and others trained in these techniques. Often a series of injections, each spaced a few weeks apart, are given. There is a great debate about the optimal number of injections and how far apart they should be done. Most agree that if an injection is not helpful, additional injections are unlikely to help. If an injection alleviates all discomfort, additional injections are not necessary. If there is some relief, but not complete resolution of symptoms, then more injections might be considered. That said, giving more and more cortisone can cause the body to suppress its own natural production of cortisol, and excessive numbers of injections should be avoided.
Side-Effects of Epidural Injections
There are quite a few known side-effects of cortisone injections that patients should understand. In addition, many patients experience unusual symptoms after a cortisone shot, and knowing how much of these symptoms was direct result of the shot is difficult. However, it is not uncommon for people to experience some side-effect as a result of a cortisone shot.
Some of the side-effects specifically related to epidural cortisone injections include:
- Infection: Very unusual, much less than 1%
- Bleeding: Also unusual, and limited by not performing this procedure on patients with bleeding disorders or while taking blood thinning medication.
- Spinal Headache: Caused by piercing the sac around the spinal nerves with the needle.
Other side-effects are possible, and should be discussed prior to injection with the doctor performing this procedure.
Effectiveness of Epidural Steroid Shots
The best reason to have an epidural steroid injection is not for the relief of back pain, but rather for the relief of leg pain caused by spinal nerve compression. Often called sciatica, leg pain caused by nerve irritation is the best reason to have an epidural. These symptoms can be caused by disc herniations or spinal stenosis. We know very well, that general low back pain symptoms are not well treated with an epidural steroid injection, and this should be avoided as a treatment for this type of pain. Back pain is not a good reason to have an epidural injection.
Epidural injections have also been used for both pre-surgical planning, and post-surgical treatment. There is some evidence to support the use of epidural steroid injections for pre-surgical planning. In these situations, your doctor may recommend have specific levels of the spine injected before surgery to confirm the location of a problem.
Doctors have also tried to use epidural steroid injections for people who have residual symptoms after a spine surgery. In these patients, injections have not been shown to be helpful and should probably be avoided.
Sources: Young IA, et al. "The Use of Lumbar Epidural/Transforaminal Steroids for Managing Spinal Disease" J Am Acad Orthop Surg April 2007