Epidural Steroid Injection

What is an Epidural Steroid Injection?

Epidural steroid injections (ESIs) are used to relieve pain located anywhere from the neck to the lower back. The needle is placed in the epidural space, the area outside the covering of the spinal cord, and a corticosteroid or anesthetic is injected. The medication coats nerve roots along the spine adjacent to the injection location and works by reducing inflammation and thus reducing the pain. Most patients experience some immediate relief, but it may take up to a week for others to feel the full effects. Depending on the nature and duration of the pain, injections may be given at varying intervals. Side effects include tenderness and possible headaches.

How is an Epidural Injection Performed?

The epidural needle is inserted into the back until the doctor feels sure it is in the epidural space. He or she will then place a small amount of lidocaine into the epidural space and wait to see if you feel warmth and numbness into your legs. If so, the needle is most likely in the correct position. The remainder of the medication is injected and the needle is withdrawn.

There are three different ways to perform an epidural injection:

Caudal Block
A caudal block is placed through the sacral gap (a space near the sacrum and below the lumbar spine), into the epidural space. This type of block usually affects the spinal nerves that are at the end of the spinal cord near the sacrum. This collection of nerves is also called the cauda equina. One of the benefits of this type of injection is less chance of a "dural puncture" also called a "wet tap". As mentioned above, the dura covers the spinal cord. It holds the spinal fluid and protects the cord and nerves from damage.

Translumbar
The most common way of performing an epidural is the translumbar approach. This type of injection is performed by placing a needle between two vertebrae from the back. The needle is inserted between the spinous processes of two vertebrae. You can actually feel the bumps that make up the spinous process by simply feeling along the back of your spine.

Transforaminal
This type of injection is a very selective injection around a specific nerve root. This type of epidural injection is used most often for diagnostic purposes, and it is commonly used in the neck. The foramina are the small openings between your vertebrae through which the nerve roots exit the spinal canal and enter the body. By injecting medication only around a specific nerve root, the doctor can determine if this is the nerve root causing the problem.

Adapted from http://www.spineuniversity.com