Epidural steroid injections

The spinal cord and the nerves leaving it are wrapped in a protective sac. The thin space between that sac and the bones of the spine is the epidural space. When a disc bulges or the spine narrows, nearby nerves can become squeezed and inflamed, causing pain that shoots down the leg (sciatica) or the arm.

An epidural steroid injection (ESI) delivers two medicines into that space, right next to the irritated nerve. A corticosteroid, a strong anti-inflammatory such as dexamethasone, triamcinolone or methylprednisolone, calms the swelling. A numbing medicine (local anesthetic) such as lidocaine or bupivacaine gives quick, short-term relief. We use live X-ray (fluoroscopy) or CT to place the needle precisely.

The injection does not shrink a herniated disc or fix narrowing. It calms the nerve, which can give your body time to heal and make it possible to do physical therapy.

On the X-ray image, a small amount of contrast dye spreads along the nerve and into the epidural space, outlining the path the medicine will follow.

Injections tend to work best for leg or arm pain from an irritated nerve, and less well for back pain alone. They can also help your surgeon decide whether surgery is likely to help.

Many sciatica episodes improve on their own over 6 to 12 weeks. An injection is often used to get through the worst of it. For long-lasting nerve pain that does not respond, a spinal cord stimulator may be an option. For arthritis-type back pain, a medial branch block followed by radiofrequency ablation can last longer.

1. 1
   Positioning

   You lie on your stomach or side on the procedure table. For neck injections, you may lie on your side or back. Your blood pressure and oxygen are monitored.

2. 2
   Numbing and guiding

   The skin is cleaned and numbed, which stings like a bee sting for a few seconds. Using X-ray or CT, the doctor guides a thin needle to the target, then injects contrast dye to confirm the medicine will flow to the right place.

3. 3
   Injecting the medicine

   The steroid and numbing medicine are injected slowly. You may feel pressure or a brief flash of your familiar pain, which usually means the right nerve is being reached.

4. 4
   Short recovery

   The needle is removed and a small bandage applied. You rest for 15 to 30 minutes, and we check that you can stand and walk safely.

The injection itself takes about 10 to 15 minutes. Depending on your pain, both sides or more than one level may be treated. Light sedation is available if you are anxious.

1. First few hours
   The numbing medicine may bring quick relief. Your leg or arm may feel numb or weak for 1 to 2 hours, so be careful standing and do not drive.
2. Days 1 to 3
   Pain may briefly return or be a little worse as the numbing wears off, before the steroid takes effect. Ice and acetaminophen (Tylenol) help. Most people return to work and normal activity the next day. Shower as usual, but no baths or pools for 1 to 2 days.
3. Days 2 to 7
   The steroid starts working. Some people notice flushing, trouble sleeping or higher blood sugar for a few days.
4. Weeks 2 to 4
   Follow-up to review your pain. If the injection helped, this is a good window to work hard on physical therapy or a home exercise program.

A pain diary for the first two weeks helps us decide whether the injection worked and what to do next.

Many people with sciatica or arm pain from a pinched nerve get meaningful relief, often lasting a few weeks to several months, and about 3 months on average. Some get lasting relief, and some little or none. If the first injection helps, it can be repeated. Many experts limit steroid injections to about 3 or 4 a year because of the effects of steroids on bones, blood sugar and hormones.

When I plan an injection, I look at the MRI and match it to where you feel the pain, so I can put the medicine next to the nerve that is actually irritated. I tell patients that the injection opens a window, not a cure. The people who do best use that window to get stronger with physical therapy.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos