all about the epidural injection

What is an epidural injection?

An epidural injection is an injection of long lasting steroid and occasionally some other medications into the epidural space. The epidural space is the area that surrounds the spinal cord and the nerves coming out of it. The epidural space is just inside the spinal canal and extends from the neck to the base of the tailbone.

What is the purpose of an epidural injection?

The long acting steroid injected reduces the inflammation and swelling of spinal nerves and other surrounding tissues in the epidural space. This may in turn reduce pain, tingling and numbness and other symptoms caused by such inflammation, irritation or swelling.

Am I a candidate for an epidural injection?

Epidural injections are most commonly performed by a pain doctor for nerve root pain into the arms or legs caused by some irritating or inflammatory process such as a disc herniation. The success rate may be as high as 70 percent or more for patients with these symptoms. Epidural injections are also quite successful for spinal stenosis or a gradually tightening of the spinal canal from degenerative processes. Epidural injections can also help degenerative disc disease, certain neuropathies, reflex sympathetic dystrophy and other conditions. In most cases, patients who have epidural injections have already tried other, more conservative, treatment such as anti-inflammatory medication, chiropractic or physical therapy.

How long does the epidural injection take?

The actual injection takes five to 10 minutes and is performed by a pain management doctor.

What is actually injected?

The injection consists of a mixture of saline, a very small amount of local anesthetic and a long acting steroid medication.

Will the epidural injection hurt?

The procedure involves a pain doctor inserting a needle through the skin and deeper tissues. There is some pain involved. However, we numb the skin and deeper tissues with a local anesthetic using a very thin needle before inserting the epidural needle. Also, the tissues in the midline have less nerve supply, so usually you feel more of a strong pressure and not as much sharp pain. Some patients choose to receive intravenous sedation that can make the procedure easier to tolerate.

Will I be “put out” for the epidural injection?

No. This procedure is done under local anesthesia. Some patients choose to receive intravenous sedation that can make the procedure easier to tolerate. The amount of sedation given generally depends upon the patient. Sometimes patients receive enough sedation that they may have amnesia and not remember parts or all of the actual procedure.

How is the epidural injection performed?

All patients receiving sedation are monitored by a pain management doctor with an EKG, blood pressure cuff and oxygen monitoring device. Patients not receiving sedation are monitored if needed. The skin of the neck or back is cleaned with antiseptic solution and then the injection is carried out. Most, if not all, neck injections are done under x-ray lying on the side. Mid and lower back injections, may or may not be done under x-ray and can be done either sitting or lying on the stomach or the side.

What should I expect after the epidural injection?

Immediately after the injection, you should feel much the same as before the injection. You may have a small numb area at the injection site. You may also have some deep ache from the passing of the injection needle. Certain patients, especially those with prior neck or back surgery around the injection site, may have some soreness or aching for a day or two. This is due to the mechanical process of needle insertion, as well as initial irritation from the volume of the medications injected. You should start noticing pain relief starting the third day or so.

What should I do after the epidural injection?

Any patient receiving sedation must have a ride home. Patients not receiving sedation are usually able to drive. Most patients are advised to take it easy for a day or so after the procedure until the medication has a chance to work. However, most patients can perform any activity that they could perform before the procedure.

Can I go back to work the next day?

You should be able to go back to work the next day unless the procedure was complicated. Usually, you will feel some soreness or aching at the injection site only.

How long does the effect of the medication last?

The long-acting steroid starts working in about 2 to 5 days and its effect can last for several days to a few months.

How many epidural injections do I need to have?

If the first injection does not relieve your symptoms within two weeks, you will be recommended to have a second injection. Similarly, if the second injection does not relieve your symptoms in another two weeks, you may be recommended to have a third injection.

Can I have more than three epidural injections?

In any given six-month period, most patients do not receive more than three injections. This is because the medication injected lasts for six months or more. If three injections have not helped you much, it is not too likely that you will get any further benefit from more injections. Also, giving more injections will increase the likelihood of side effects from the medications injected. If a patient gets six months or more relief from a series of epidural injections, they may be repeated again in the future.

Is an epidural injection the same thing that women have for labor pain?

Not exactly. The epidural injection is certainly injected into the same space. However, for women in labor, a much larger introducer needle is used so that a catheter can be threaded into the epidural space. Then an injection and infusion of numbing medicine or local anesthetic is used to decrease the sensation of labor pain. This amount of numbing may make it difficult to walk or even move the legs. Epidural injections, on the other hand, rely primarily on the effect of a long acting steroid to relieve pain by decreasing inflammation and swelling. Very little local anesthetic is used so that there is no weakness or numbness of the arms or legs after the epidural injection.

Will the epidural injection help me?

It is sometimes difficult to predict if the injection will help you or not. The patients who have pain down into the arms or legs from irritated spinal nerve roots respond better to the injections than the patients who have only neck or back pain. Similarly, the patients with a recent onset of arm or leg pain may respond much better than patients with longstanding pain. Also, the patients with primarily neck or back pain that is mainly due to bony abnormalities may respond, but the effect may not be as long as for those with associated arm or leg pain.

Are caudal blocks and saddle blocks the same as epidural injections?

For the most part, yes. The caudal canal that passes through the tailbone or sacrum is the extension of the epidural space from the base of the spine. Usually there is a small opening at the end of the tailbone called the sacral hiatus. Placing a needle into this opening and injecting through it is called a caudal injection. If sufficient local anesthetic is used in the medicine injected, it will cause a caudal or saddle block or numbness where the body would come into contact with a saddle when seated on one. A caudal injection may be preferable when the spinal nerve roots involved are in the area where the body would contact a saddle.

What are the risks and side effects of epidural injections?

Generally speaking, epidural injections are is safe. However, with any procedure there are risks, side effects and possibility of complications. The most common and usually temporary side effects are bruising, soreness or other pain at the injection site. Uncommon risks involve spinal puncture with headaches, infection, bleeding inside the epidural space, nerve damage or worsening of symptoms. Other risks are related to the side effects of the long acting steroid such as weight gain, increase in blood sugar in diabetics, water retention or suppression of body’s own natural production of steroids.

Who should not have an epidural injection?

If the patient allergic to any of the medications injected, is on a blood-thinning medication, has an active infection going on or has poorly controlled diabetes or heart disease, they should not have the injection or at least consider postponing it if postponing would improve your overall medical condition.

Adapted from: http://www.medcentral.org/body.cfm?id=345 July 35th, 2010