Anatomy and Physiology
The spine consists of the: bony vertebrae stacked one on the other, shock-absorbing intervertebral discs lying between the vertebrae, ligaments and muscles connecting the bones, and the spinal cord with its branching spinal nerves.
The spinal cord is bathed in cerebrospinal fluid and surrounded by a protective membrane called the dura. Just outside this membrane is the epidural space. The spinal nerves emanate from the spinal cord at regular intervals.
Each spinal nerve passes through a narrow opening between the vertebral bones and behind the intervertebral discs. Spinal nerves in the lumbar or lower back region come together to form the larger nerves that pass into the legs and pelvis.
Reasons for Procedure
The intervertebral discs consist of two parts: a tough outer layer called the annulus fibrosis and a spongy inner material called the nucleus pulposus.
With normal aging, or on account of injury, the annulus fibrosis may weaken or degenerate. When this occurs the disc may bulge, resulting in inflammation and pain.
If the annulus completely breaks down, the nucleus may ooze through, causing a disc herniation. The resulting inflammation and swelling may irritate one of the spinal nerves nearby, resulting in a condition known as radiculopathy. Disc herniations in the lower, or lumbar, region of the back tend to produce shooting pain down the leg, a condition known as sciatica. if a disc herniates in the neck, the pain radiates into the arm.
Other conditions can also cause pain and inflammation in the area of the spinal nerves. Degenerative discs, for example, are often accompanied by osteoarthritis, which can affect numerous joints in the body. Osteoarthritis may cause excess bone growth at the joints of the spine, resulting in the compression of the nearby spinal nerves.
An epidural steroid injection is a minimally invasive procedure used to temporarily relieve inflammation in the spine-reducing pain and allowing time for the condition to hopefully heal on its own.
Low back pain is the most common cause of missed workdays. Most cases resolve on their own in 1-6 weeks. Conservative treatment begins with 1-2 days of rest followed by gradually increasing activity and exercises to stretch the ligaments and strengthen the muscles of the lower back. If pain persists, doctors may prescribe oral medications and physical therapy.
When conservative treatments do not relieve the pain, doctors can inject medications into the epidural space near the inflamed region. Steroid injections, the most commonly prescribed, deliver a powerful anti-inflammatory effect to the site of the inflammation, particularly when caused by a disrupted intervertebral disc.
The effects of epidural steroid injections, which begin within a day or two, tend to last from weeks to months. If successful, they can be repeated, usually up to three times per year.
When conservative treatments fail to resolve the pain, or if a herniated disc is clearly producing persistent or worsening neurologic symptoms, surgery to relieve pressure on a spinal nerve may be indicated.
In the days leading up to your procedure: arrange for a ride to and from the hospital, and for help at home as you recover. The night before, eat a light meal, and do not eat or drink anything after midnight. Your doctor will need to know if you regularly take medications, herbs, or dietary supplements, especially those that thin the blood, such as aspirin, Coumadin®, or anti-inflammatory medications. Do not start taking any new medications, herbs, or dietary supplements before consulting your doctor.
Your procedure may need to be postponed if your have signs of an infection or very high blood pressure.
To begin your procedure, you will lie on your abdomen. Your doctor will clean the skin on your back with a swab and then numb it with a local anesthetic similar to the novocaine your dentist uses.
Using an x-ray image for guidance, your doctor will insert a needle between the bones and through the ligaments of your spine until it reaches the epidural space at the level of the inflammation.
Once the needle has been inserted into the epidural space, your doctor will inject the steroid solution. The entire procedure takes about 15-20 minutes.
Your vital signs will be monitored for another 15-20 minutes before you are released to go home.
Risks and Benefits
Complications of epidural steroid injections are rare, but can include: headache from a "wet tap" that inadvertently leaks cerebrospinal fluid, allergy to the anesthetic or steroid medication, excessive bleeding, infection, and/or nerve damage.
Potential benefits of epidural steroid injections include: a temporary reduction in the pain caused by radiculopathy, repeat dosing possible and usually effective, no need for a large incision or a lengthy recovery period; most patients find they can resume their normal routines within a day or so, avoidance of the widespread adverse effects associated with oral steroid therapy. In an epidural steroid injection, or any procedure, you and your doctor must carefully weigh the risks and benefits to determine whether it's the most appropriate treatment choice for you.
After the Procedure
After your procedure, any lingering pain in the injection area usually responds to ice and/or over-the-counter pain medications. You will not be able to drive yourself home after the procedure, but should be able to resume driving the next day.
Once you are home, be sure to contact your doctor if you experience: signs of infection, such as fever, chills, or drainage from the injection site, persistent or worsening headache, loss of control of your bladder or bowels, severe pain in your back or legs, and/or new numbness or weakness in your legs.