Epidural Steroid Injections (ESIs) are a common method of treating inflammation
associated with low back related leg pain, or neck related arm pain. In both of
these conditions, the spinal nerves become inflamed due to narrowing of the
passages where the nerves travel as they pass down or out of the spine.
Why Get an Epidural Steroid Injection?
Narrowing of the spinal passages can occur from a variety of causes, including
disc herniations, bone spurs, thickening of the ligaments in the spine, joint
cysts, or even abnormal alignment of the vertebrae (‘slipped vertebrae’, also
known as spondylolisthesis). The epidural space is a fat filled ‘sleeve’ that
surrounds the spinal sac and provides cushioning for the nerves and spinal
cord. Steroids (‘cortisone’) placed into the epidural space have a very potent
anti-inflammatory action that can decrease pain and allow patients to improve
function. Although steroids do not change the underlying condition, they can
break the cycle of pain and inflammation and allow the body to compensate for
the condition. In this way, the injections can provide benefits that outlast
the effects of the steroid itself.
How Are Epidural Steroid Injections Performed? There
are three common methods for delivering steroid into the epidural space: the interlaminar, caudal, and transforaminal
approaches. All three approaches entail placing a thin needle into position
using fluoroscopic (x-ray) guidance. Prior to the injection of steroid,
contrast dye is used to confirm that the medication is traveling into the
desired area. Often, local anesthetic is added along with the steroid to
provide temporary pain relief.
An interlaminar ESI, often referred
to simply as an ‘epidural injection’, involves placing the needle into the back
of the epidural space and delivering the steroid over a wider area. Similarly,
the caudal approach uses the sacral hiatus (a small boney opening just above
the tailbone) to allow for needle placement into the very bottom of the
epidural space. With both approaches, the steroid will often spread over
several spinal segments and cover both sides of the spinal canal. With a transforaminal ESI, often referred to
as a ‘nerve block’, the needle is placed alongside the nerve as it exits the
spine and medication is placed into the ‘nerve sleeve’. The medication then
travels up the sleeve and into the epidural space from the side. This allows
for a more concentrated delivery of steroid into one affected area (usually one
segment and one side). Transforaminal ESIs can also be modified slightly
to allow for more specific coverage of a single nerve and can provide
diagnostic benefit, in addition to improved pain and function.
All three procedures are performed on an outpatient basis, and you can usually
return to your pre-injection level of activities the following day. Some
patients request mild sedation for the procedure, but many patients undergo the
injection using only local anesthetic at the skin.
What Happens After the Injection? The
steroid will usually begin working within 1-3 days, but in some cases it can
take up to a week to feel the benefits. Although uncommon, some patients will
experience an increase in their usual pain for several days following the
procedure. The steroids are generally very well tolerated, however, some
patients may experience side effects, including a ‘steroid flush’ (flushing of
the face and chest that can last several days and can be accompanied by a feeling
of warmth or even a low grade increase in temperature), anxiety, trouble
sleeping, changes in menstrual cycle, or temporary water retention. These side
effects are usually mild and will often resolve within a few days. If you are
diabetic, have an allergy to contrast dyes, or have other serious medical
conditions, you should discuss these with your doctor prior to the injection.
Epidural steroid injections have been performed for many decades, and are
generally considered as a very safe and effective treatment for back and leg
pain or neck and arm pain. Serious complications are rare, but could include
allergic reaction, bleeding, infection, nerve damage, or paralysis. When
performed by an experienced physician using fluoroscopic guidance, the risk of experiencing
a serious complication is minimized. Overall, ESIs are usually very well
tolerated and most patients do well.
Although not everyone obtains pain relief with ESIs, often the injections can
provide you with improvement in pain and function that last several months or
longer. If you get significant benefit, the injections can be safely repeated
periodically to maintain the improvements. Injections are also commonly coupled
with other treatments (medications, physical therapy, etc) in an attempt to
either maximize the benefit or prolong the effects. You should consult with
your doctor to develop a comprehensive care plan.