An epidural injection delivers steroids into the epidural space around spinal nerve roots to relieve pain - back pain, leg pain, or other pain - caused by irritated spinal nerves. The steroid used in the epidural steroid injection reduces the inflammation of those nerves, which is often the source of the pain.
It is important to note that an epidural steroid injection should not be considered a cure for back pain or leg pain: rather, the goal is to help patients get enough pain relief in order to be able to progress with their rehabilitation program.
An epidural steroid injection significantly reduces pain for approximately 50% of patients. It works by delivering steroids directly to the painful area to help decrease the inflammation that may be causing the pain. It is thought that there is also a flushing effect from the injection that helps remove or "flush out" inflammatory proteins from around the structures that may cause pain. In addition to relieving pain, the process of natural healing can occur more quickly once the inflammation is reduced.
Spinal nerves can become inflamed due to irritation from a damaged disc or from contact with a bone spur. Depending on which part of the spine the inflamed nerves are located in, pain and/or other symptoms (such as numbness, tingling) may be experienced in different areas of the body, as shown:
Nerve irritation in the cervical spine
- Neck pain, or tingling, numbness
- Shoulder pain, or tingling, numbness
- Arm pain, or tingling, numbness
Nerve irritation in the thoracic spine
- Upper back pain
- Pain along the ribs to the chest wall
- Pain in the abdomen (rarely)
Nerve irritation in the lumbar spine
Anatomy of the Spinal Nerves and Dura
There is a membrane called the dura covering the nerve roots in the spine. Around the dura is a sleeve-like space called the epidural space. Before nerves can travel from the spine into the arms, chest, and legs, they travel through the epidural space, and exit through small nerve holes. The medication from the epidural steroid injection is placed in the epidural space.
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Epidural Steroid Injection Procedure
The injection procedure for an epidural includes the following steps:
- An IV is started so that medicine can be given for relaxation if desired.
- The patient lies face down on an X-ray table and the skin is well cleaned with an antiseptic.
- The area where the epidural needle will be inserted is numbed with a local anesthetic.
- Fluoroscopy (a guided X-ray procedure where the doctor can watch the placement and movement of the needle) will be used to direct a small needle into the epidural space. The patient will feel some pressure during this part. Fluoroscopy is important in this procedure to help ensure correct placement of the medications.
- A contrast dye is injected to confirm that the medicine spreads to the affected nerve(s) in the epidural space.
- A combination of numbing medicine (an anesthetic) and time released anti-inflammatory medicine (a steroid) is injected.
The procedure usually takes approximately 30 minutes, followed by about 45 minutes of recovery time at the clinic. On the day of the epidural steroid injection the patient should not drive. Rest is needed and strenuous activities must be avoided on the day of the epidural steroid injection.
Epidural Injection Results and Follow-up
Following the epidural injection, some partial numbness from the anesthetic may occur in the patient's arms or legs. Any partial numbness usually subsides after a few hours. Any remaining pain needs to be reported to the physician, and ideally the patient should keep a "pain diary" to record the pain relief experienced over the next week. After the pain diary is returned to the treating physician, the physician should be kept informed of the results in order to plan future tests and/or treatment if needed.
There may be an increase in the patient's pain that may last for up to several days. This may occur after the numbing medicine wears off but before the steroid has had a chance to work. Ice packs may help reduce the inflammation and will typically be more helpful than heat during this time. Improvements in pain will generally occur within 10 days after the epidural injection, and may be noticed as soon as one to five days after the injection.
Regular medicines may be taken after an epidural steroid injection. On the day following the procedure, the patient may return to his or her regular activities. When the pain has improved, regular exercise may be resumed in moderation. Even if improvement is significant, activities should be increased slowly over one to two weeks to avoid recurrence of pain.