Epidurals for Back Pain: Lumbar Epidural Steroid Injections
Epidural steroid injections in the low back are the most common type of spinal injections that I perform in my practice. The goal of epidural injections is to deliver anti-inflammatory medication (similar to cortisone) as close as possible to irritated and painful nerves, often seen in conditions like sciatica from disc herniation, spinal stenosis, and failed back surgery syndrome, among others. It is a very common procedure (millions done every year in the United States) with a long history (first done for low back pain in 1925).
What Kind of Back Pain Responds to Epidural Steroid Injections?
As mentioned above, there are many problems in the low back that can cause painful nerve irritation. Epidural injections are most effective for these conditions, and would not be expected to help other kinds of low back pain. Epidural injections are most effective for radiating back pain, like sciatica pain, as compared to axial back pain which is limited to the center of the low back.
How does the Epidural Reduce Pain?
There are several likely mechanisms involved in back pain relief from epidural injections. Corticosteroids are potent anti-inflammatory medications, so they may directly block swelling at the nerve roots and improve blood flow. They may also directly work on C-fiber nerve cells (the ones responsible for pain) to reduce their activity. It is also possible that the spinal injection of fluid dilutes the chemicals in the spine that cause inflammation and irritation, effectively rinsing them away. Pain relief from epidural steroid injections can last for months, and they can be repeated safely as needed.
What are the Different Types of Epidural Steroid Injections?
There are three categories of epidural injections, determined by which opening in the spine is used for the procedure. Interlaminar Epidurals enter near the center of the spine. Transforaminal Epidurals enter an opening in the side of the spine where the nerve root emerges, sometimes enabling increased focus of the treatment. Caudal Epidurals are done through an opening near the bottom of the sacrum at the bottom of the spine. Many factors go into determining which technique is likely to work best for you.
What are the Risks of Epidural Injections?
Overall, epidurals are safe spinal injections that have been used for nearly a century in the treatment of low back pain. The most common complication is that of spinal headache, which in large studies seem to occur in 1 out of 100-200 epidural injections. Various treatments are available if this occurs. Rare complications include infections, bleeding problems, nerve injuries, and reactions to the medication. These complications are so rare that it is hard to estimate the percentage risk. Sterile technique and live X-ray reduce the odds of these complications.
The recent complication of fungal meningitis after epidural injections has been in the news. This was a complication caused by contaminated medication from compounded pharmacies, which some doctors used to cut costs. I have never and will never use compounded medication for epidurals because they do not have the same FDA oversight as epidural medication formulated by the pharmaceutical companies themselves in sterile packaging. There are no cases of fungal meningitis from epidurals that are done with the medication that I use.
What’s the Difference Between an Epidural Steroid Injection and a Labor Epidural?
Many patients ask what the connection is between these epidural injections, and the epidurals that some women choose to receive during labor. Both types of epidural injections deliver medicine to the epidural space, an area inside the bones of the spine but outside the dura mater, which contains spinal fluid, spinal nerves, and the spinal cord. However, there are a few key differences.
First, labor epidurals use local anesthetic to block sensation from the lower part of the body. This also blocks motor nerves, temporarily weakening leg movement. Epidural steroid injections use anti-inflammatory steroid medications which do not direct block sensation or motor function.
Second, today’s labor epidurals are almost always continuous epidurals, which leave a catheter in the back to deliver constant medication for hours. Epidural steroid injections leave nothing behind except medicine.
Third, labor epidurals are done blindly, by feel. In nonpregnant patients, I am able to use live X-ray to see the spine and my needle, for improved accuracy and safety. I can visually confirm that medication is going to the right place.
Image Credit: BruceBlaus [CC-BY-3.0], via Wikimedia Commons