An epidural steroid injection is a block that is most commonly used to decrease pain and inflammation. This treatment can be highly effective because it delivers the anti-inflammatory medication and pain relief directly to the source of the problem.

Epidural steroid injections are used to decrease the inflammation associated with a variety of spinal conditions, such as herniated disc, spinal stenosis, or degenerative disc disease, enabling the patient to pursue physical therapy/rehabilitation. While patients often experience a reduction in pain following an epidural steroid injection, there seems to be a better response when the injections are coupled with an organized therapeutic exercise program.

Before an Epidural Steroid Injection
An epidural steroid injection usually takes between 15 and 30 minutes. The patient lies flat on an x-ray table on their abdomen. Prior to the epidural injection, the skin is numbed with lidocaine, which is similar to the Novocain that the dentist uses (a "local" anesthetic).

What to Expect During an Epidural Steroid Injection
An epidural steroid injection is generally administerd using the following process:

Using fluoroscopy (live x-ray) for guidance, the physician injects steroids into the epidural space — that area that lies between the inner surface of the bony vertebral column and the outer, sleeve-like covering (the dura) of the spinal cord. Sometimes a flushing solution (either lidocaine or normal saline) is also used to help "flush out" inflammatory proteins from the region that is believed to be the source of pain.

The epidural steroid injection procedure is usually not uncomfortable; however, sedation is available for patient anxiety and comfort. Sedatives are rarely necessary. If a sedative is used, the patient will need to be monitored for a longer period following the injection.

The procedure takes about 30 minutes, plus approximately forty-five minutes recovery time.

Following the injection, the patient is usually monitored for 15 to 20 minutes before being discharged to go home. Patients are usually asked to rest on the day of the epidural steroid injection. Normal activities (those that were done the week prior to the epidural injection) may typically be resumed the following day.

Success Rates
An epidural steroid injection is generally successful in relieving pain for approximately 50% of patients. If a patient does not experience any back pain or leg pain relief from the first epidural injection, further injections will probably not be beneficial. However, if there is some improvement in back pain or leg pain, one to two additional epidural steroid injections may be recommended.

How Frequently Can Epidural Steroid Injections be Performed?
There is no definitive research to dictate the frequency of how often a patient should have epidural steroid injections for low back pain and/or leg pain. In general, it is considered reasonable to perform up to three epidural injections within a six-month period.

Typically, epidural steroid injections are done in two-week intervals. However, there is no general consensus in the medical community as to whether or not a series of three injections need always be performed. If one or two injections lessen the patient's low back pain and/or leg pain, some physicians prefer to save the third epidural steroid injection for any potential recurrences of back pain later in the twelve-month period.

Potential Risks and Side Effects
As with all invasive medical procedures, there are potential risks associated with lumbar (lower back) epidural steroid injections. Generally, however, there are few risks associated with epidural steroid injections and they tend to be rare. Risks may include:

Infection. Minor infections occur in 1% to 2% of all injections. Severe infections are rare.

Bleeding. Bleeding is a rare complication and is more common for patients with underlying bleeding disorders.

Nerve damage. While extremely rare, nerve damage can occur from direct trauma from the needle, or secondarily from infection or bleeding.

Dural puncture ("wet tap"). A dural puncture occurs in 0.05% of injections. It may cause a post-dural puncture headache (also called a spinal headache) that usually gets better within a few days. Although rare, a blood patch may be necessary to alleviate the headache.

Paralysis is not a risk since there is no spinal cord in the region of the epidural steroid injection.

In addition to risks from the injection, there are also potential side effects from the steroid medication. These side effects tend to be rare, though they become more common when steroids are taken daily for several months. These risks and side effects may include:

A transient decrease in immunity
High blood sugar
Stomach ulcers
Severe arthritis of the hips (avascular necrosis)
Cataracts
Transient flushing
Increased appetite

Who Should Avoid Epidural Steroid Injections?
Lumbar epidural steroid injections should not be performed on patients who:

Have a local or systemic bacterial infection
Are pregnant (if fluoroscopy is used)
Have bleeding problems
May be suffering from a tumor or infection (if suspected, an MRI scan should be done prior to the injection to rule out these conditions)
Are suspected of having allergies to the injected solution, uncontrolled medical problems (such as congestive heart failure and diabetes)
Are taking aspirin or other antiplatelet drugs/blood thinners (epidural steroid injections can be given once these medications have been stopped; however, patients need to consult with their physician before discontinuing them)