Spinal injections are not new – the use of spinal injections to treat low back pain was first documented in 1901, and in 1952 epidural steroid injections were first used to treat low back pain with associated sciatica (pain in the sciatic nerve due to lumbar disc herniation). Today, epidural steroid injections have become an integral part of non-surgical management of low back pain.
An epidural injection is typically used to alleviate chronic low back and/or leg pain. While the effects of the 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 effective in significantly reducing pain for the majority of patients. It works by delivering steroids directly to the painful area to help decrease the inflammation that may be causing the pain.
How an epidural steroid injection works
An epidural is an injection that delivers steroids directly into the epidural space in the spine. Sometimes a local anesthetic is also used to help numb the nerve and provide immediate, though temporary, relief.
The epidural space is the space between the dura mater (a membrane) and the vertebral wall and is filled with fat and small blood vessels. It is located just outside the dural sac. The dural sac surrounds the nerve roots and cerebrospinal fluid (the fluid that the nerve roots are bathed in).
Epidural steroid injections for inflammation
There are often inflammatory factors and other substances that generate pain that are associated with a lumbar disc herniation, and this inflammation, with an associated impingement on the exiting nerve roots, can cause significant nerve root irritation and swelling.
Steroids (corticosteroids) have been shown to reduce inflammation by inhibiting the production of substances that cause inflammation; the epidural steroid injection can be highly effective because it delivers the medication directly to the site of inflammation.
Epidural steroid injections for rehabilitation
In general, an epidural steroid injection is used to help provide pain relief to enable patients to progress with their rehabilitation. Individuals who have less back pain and feel more comfortable are generally able to work on the active therapies—such as stretching, core reconditioning, strengthening/pain relief exercises and low impact aerobic conditioning—that are critical in rehabilitating the lower back and helping prevent (or minimize) future episodes of low back pain.
Epidural steroid injections for pain
Several common conditions—including a lumbar disc herniation, degenerative disc disease, and lumbar spinal stenosis—can cause severe acute or chronic low back pain 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.
Before the epidural steroid injection
An epidural steroid injection usually takes between 15 and 30 minutes. The patient lies on an x-ray table usually on their abdomen. Prior to the epidural injection, the skin is numbed with an anesthetic, which is similar to the novocaine that the dentist uses (a "local" anesthetic).
Many types of physicians can be qualified to perform an epidural steroid injection, including an anesthesiologist, radiologist, neurologist, physiatrist and surgeon. Often these physicians may possess additional credentials, such as board certification in pain management.
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 to ensure precise accuracy in the placement of the medications as controlled studies have found that often medications are misplaced in up to one third of epidural steroid injections that are done without fluoroscopy.
During and after the epidural steroid injection
Once the needle is in the exact position, the epidural 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 epidural steroid injection 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 epidural injection) may typically be resumed the following day.
Patients will find that the benefits of an epidural steroid injection include a reduction in pain, primarily in leg pain. Patients seem to have a better response when the epidural steroid injections are coupled with an organized therapeutic exercise program.
Pain relief from an epidural steroid injection
While the effects of an epidural steroid injection tend to be temporary—providing relief from pain for one week up to one year—an epidural injection can be very beneficial for patients during an episode of severe back or leg pain. Importantly, it can provide sufficient pain relief to allow the patient to progress with their rehabilitation program.
Epidural steroid injection success rates
An epidural steroid injection is generally successful in relieving pain in a significant majority of patients. If a patient does not experience any back pain or leg pain relief from the first epidural injection, further injections may or may 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.
Risks of an epidural steroid injection
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, 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.
In addition to risks from the injection, there are also potential risks and side effects from the steroid medication. These side effects from an epidural steroid injection tend to be rare. Side effects from steroids are more common when taken daily for several months. 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.
Lumbar epidural steroid injections should not be performed on patients who have a local or systemic bacterial infection, are pregnant (if fluoroscopy is used) or have bleeding problems. Epidural steroid injections should also not be performed on patients whose pain is from a tumor or infection, and if suspected, an MRI scan should be done prior to the injection to rule out these conditions.
Injections may be done, but with extreme caution, for patients with allergies to the injected solution, uncontrolled medical problems (such as congestive heart failure and diabetes), and those who are taking aspirin or other antiplatelet drugs (e.g. Ticlid, Plavix), or other blood thinners, such as Coumadin, Heparin or Lovenox.
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 per year based upon the individual needs of the patient.
Epidural steroid injection timing varies
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 significantly 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.
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Injection Types
