What is Epidural Steroid Injection (ESI)?

Epidural Space is the space outside the covering of the spinal cord called the dura. This space runs the entire length of the spine. Nerves exit from the spinal cord and travel through the epidural space to reach the neural foramen. Inflammation of these nerve roots occur when they are pinched by bone spurs or ruptured disc. This may result in radiating pain down the arm or leg.

An epidural is an injection that delivers corticosteroids (cortisone) directly into the epidural space. Sometimes a flushing solution (either lidocaine or normal saline) is also used to help "flush out" inflammatory proteins from around the area that may be the source of pain.

Steroids (corticosteroids) have been shown to reduce inflammation by inhibiting the production of substances that cause inflammation, the epidural injection can be highly effective because it delivers the medication directly to the site of inflammation.

Epidural steroid injection in the neck region is called Cervical Epidural Steroid Injection (CESI). In the lower back, it is called the Lumbar epidural Steroid Injection (LESI). These are the common sites, but occasionally thoracic epidural steroid injection (TESI) is performed for mid back pain.

When is an epidural typically recommended ?

In general, epidural injections are used to help provide pain relief to enable patients to progress with their rehabilitation. Individuals who have less pain and feel more comfortable are generally able to work on the active therapies—such as stretching, strengthening/pain relief exercises and low impact aerobic conditioning—that are critical in rehabilitating the lower back.

Several common conditions—including lumbar disc herniation, degenerative disc disease, and lumbar spinal stenosis—can cause severe acute or chronic low back and/or leg pain. For these and other conditions that can cause chronic pain, an epidural steroid injection may be an effective non-surgical treatment option.

How is the injection performed ?

An epidural steroid injection usually takes about 10 minutes. The patient lies flat on an x-ray table on their abdomen. Prior to the injection, the skin is numbed with lidocaine, which is similar to the novocaine that the dentist uses (a "local" anesthetic).

Using fluoroscopy (live x-ray) for guidance, the physician directs a needle toward the epidural space. Fluoroscopy is considered important in guiding the needle into the epidural space, as controlled studies have found that medication is misplaced in 13% to 34% of epidural injections that are done without fluoroscopy, called " blind " injections. Experienced anesthesiologist often practice blind injections, but their placement of needle can not be verified. Dr. Thiyaga does not practice blind procedures. Images are recorded on x-ray paper and available for inspection by the patient or third party for verification of needle placement and administration of medication at the most appropriate site. Since patients who fail epidural steroid injections under go open spine surgery, we consider it is our duty to ensure that the spinal procedure is done in a verifiable manner.

Once the needle is in the exact position, the steroid solution is injected. Following the injection, the patient is usually monitored for 15 to 20 minutes before being discharged to go home.

Sedation is available for patient anxiety and comfort. However, sedatives are rarely necessary, as the procedure is usually not uncomfortable. If a sedative is used, the patient will need to be monitored for a longer period following the injection.

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 injection) may typically be resumed the following day

What are the benefits?

The benefits of the epidural steroid injections include a reduction in pain, primarily in leg pain. Patients seem to have a better response when the injections are coupled with an organized therapeutic exercise program.

While the effects of an epidural injection tend to be temporary—providing relief from pain for one week up to one year—an epidural can be very beneficial for patients during an episode of severe back pain. Importantly, it can provide sufficient pain relief to allow the patient to progress with their rehabilitation program.

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

What are the potential risks and side effects ?

As with all invasive medical procedures, there are potential risks associated with epidural steroid injections. We encourage our patients to try non-invasive treatment options prior to injections. Risks may include:

• Infection. Minor infections occur in 1% to 2% of all injections. Severe infections are rare, occurring in 0.1% to 0.01% of injections.

• 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 0.5% 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.

How frequently can epidural steroid injections be performed?

There is no definitive research to dictate the frequency of epidural steroid injections for low back pain and/or leg pain. In general, it is considered reasonable to perform up to three injections per year.

Typically, epidural injections are done in 3-4 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 and/or leg pain, we prefer to save the third injection for any potential recurrences of back pain later in the twelve-month period.

Is there any difference between the first and the second ESI?

Yes, in the lumbar region, every ESI is different in technique. The first ESI usually targets the posterior epidural space, the technique is called interlaminar ESI. The second ESI is called the transformational ESI which targets the lateral and the anterior epidural space. Occasionally we also perform a caudal ESI, especially if there is epidural scarring at the site of open surgery. In the cervical region we usually perform the interlaminar ESI. Transforaminal ESI is used very selectively.

What is your success rate ?

Based on experience, our success rate is about 30-50% with each injection. Best results are seen in patients with radiating pain. Axial pain due to disc degeneration, central spinal stenosis might not be relieved with ESI. Sometimes we may have to do more than one procedure at multiple sites. Since the outcome measures in pain management is difficult to determine, we do not audit success rates. Chronic cigarette smokers, failed back surgical patients tend to do poorly with ESIs.