EPIDURAL STEROID INJECTIONS
The spinal cord runs within the bony structure of the vertebral column and is encased by three membranous sacs: The dura mater, the arachnoid mater, and the pia mater. The pia mater is adherent to the brain and spinal cord. The dura mater and arachnoid mater are adherent to each other and together are often referred to more simply as dura. The sub-arachnoid space (between the arachnoid mater and the pia mater) contains spinal fluid (CFS) that bathes and nourishes the spinal cord. The epidural space is between the outer surface of the dural sac and the bones of the vertebral column. It completely surrounds the dura but does not contain any fluid. Instead, it is filled with epidural fat and a large network of blood vessels.
Transforaminal Epidural Steroid Injection
Nerves from the upper and lower limbs (including the nerves that make up the sciatic nerve) enter the vertebral column and pierce the dural sac to reach the spinal cord. For various reasons these nerves can become irritated as they enter the vertebral column and cause pain in the lower limbs. This pain is felt as shooting down the lower limb and is referred to as nerve root pain or, technically, radicular pain (from the Latin word redix, a root). The common name for this sort of pain in the lower back and leg is sciatica.
The term epidural steroid injection refers to the injection of corticosteroids into the epidural space of the vertebral column as a means of treating pain caused by irritation of the spinal nerve.
How does it work?
There are two ways in which it is thought that epidural steroid injections may work, however there is little scientific evidence supporting either of these theories.
The first belief is that some leg pain involves the inflammation of one or more of the nerves, their covering, or their roots, in the back. The injection of steroids directly into the part of the spinal column called the epidural space is thought to aid in reducing this inflammation.
Caudal Epidural Steriod
The other belief is that the corticosteroids act like a local anesthetic and block the pain long enough to allow the body to begin the process of repairing itself. The chief effect of an epidural steroid is to reduce pain. Pain relief from epidural injections, in conjunction with therapy, has been proven to provide long lasting relief of back and leg pain. On occasion, patients will get relief for only a few weeks or months, and in those cases the doctor may opt to repeat the procedure. Some patients do not experience any pain reduction and may in fact suffer an increase in pain and/or other symptoms, as detailed later.
How is an epidural steroid injection administered?
Certain medications may increase the risk of complications. If you are taking aspirin you should stop it (5) five days prior to the procedure. If you are on Coumadin (Warfarin), Heparin, Lovenox (Enoxoparin), Ticlid (Ticlopidine), Plavix (Clopidogrel), or other blood thinning agents such as anti-inflammatory agents, please let your physician at the time of scheduling the procedure. You can continue to use Celebrex (Celecoxib) before the procedure. Do not take your regular pain medication for six hours before or after the procedure. You should continue to take your routine medications (such as high blood pressure and diabetes medication) before the procedure. If you are on antibiotics please notify your physician, he may wait to do the procedure. If you have an active infection or fever we will not do the procedure.
Unless you have been instructed otherwise, you may eat and/or drink prior to your procedure. You are expected to have a ride to and from the procedure. The procedure usually takes about a half an hour though you may be at the office/facility for as long as three hours. You will be placed into an examination area and your vitals will be taken. You will meet with the physician prior to your procedure. You will then be placed in the procedure area and prepped for your injection.
A local anesthetic will be injected into the skin and underlying tissues to decrease the discomfort of introducing the epidural needle. Once the local anesthetic is working, the epidural needle is advanced into the epidural space using the bones as landmarks. Your physician will use fluoroscopy (a live x-ray) and other technical aids to ensure that the needle is in the right place. The physician may do the procedure through an opening on the side of the spine where a nerve root comes out (transforaminal approach), through the middle of the neck or back (intralaminar approach), or through a small opening in the sacrum, near the tailbone (caudal approach). Local anesthetic will be injected into the skin and underlying tissues to decrease the discomfort of introducing the epidural needle.
When the needle is in the epidural space, a syringe containing the corticosteroid solution is connected to the needle. After making sure that the needle is not in a blood vessel or in the spinal fluid, the doctor injects the solution slowly. The doctor will ask you to describe how you are feeling while the solution is being injected.
You may briefly feel pins and needles in the arms or legs (depending on the site of injection). You may get a headache. If the needle touches a nerve you will feel a sharp local pain. You should tell your doctor about these feelings.
The corticosteroid will be injected with a local anesthetic; however the dosage and the volume of the steroid and the other components will vary according to the doctor's judgment.
Following the injection, you will be asked to stay at the office or surgery center for about 20-30 minutes until you adequately recover from the procedure. While recovering, you will be monitored for any adverse reactions to the procedure. Once you are feeling well enough to walk, you will be allowed to leave with your ride. You are expected to follow up in the office about 12 days after your procedure, so that you may discuss how you are feeling, side effects (if any) and help him determine whether or not to perform another injection.
What are the risks of an epidural steroid injection?
With any operation or injection procedure there are risks. In the case of epidural steroid injections these risks are small, most occurring well under one percent of the time.
There are a variety of side effects and complications, most of which relate not to the steroid itself, but to the way the injection is given.
The most common side effect is a temporary increase in pain. It occurs in about one percent of epidural steroid injections and appears to be related to the volume of substance injected into the epidural space.
Headache, another complication with an incidence of one percent, can be normal and related to the volume of fluid injected into the epidural space or may be related to the accidental puncture of the innermost membrane which surrounds the spinal cord. The headache is caused either by a leakage of the fluid surrounding the spine, or as a result of an accidental injection into the spinal fluid. In most cases it may be necessary to repeat the epidural procedure, this time injecting some of the patient's own blood, taken from a vein in the arm, which forms a small clot allowing any puncture of the membranes surrounding the nerve to heal.
If you are allergic to one of the additives in the steroid solution you may experience a hot flush or develop a rash. However, this should get better within a few hours or days.
As with any injection through the skin, it is possible for bacteria to gain entry, causing an infection. The risk of this with an epidural injection is very small.
It is also theoretically possible that a nerve could be damaged. In the procedure the needle is inserted very slowly and if the lining around the nerve were touched there would be pain in the arm or leg. The doctor would then change the position of the needle slightly to avoid any risk of damage to the nerve.
The most ominous reports of complications are associated with epidural steroid injections in the neck. There have been reports of spinal cord injuries, strokes and deaths (all of these are very, very rare) which occurred when the physician injected the medication into the wrong area. Once again, your physician will use fluoroscopy and other technical aides to absolutely minimize the risk of this.
Some side effects may occur as a result of the corticosteroid administered. If you have diabetes, you may notice that your blood sugars are elevated for 2-3 days following this procedure. If they are, usually only monitoring is required. However, if you are concerned, call your physician. Corticosteroids may also cause fluid retention, weight gain, alteration in skin pigmentation at the site of injection, fluid and electrolyte alteration and/or gastrointestinal upset. These side effects are usually not serious.
Certain other side effects may occur if the wrong amounts of local anesthesia or corticosteroid are injected into the epidural space or if the drugs are accidentally injected into the spinal fluid. These side effects are extremely rare if the procedure is properly performed.
These side effects include:
Swelling of the face or other parts of the body
High blood pressure
Irritation or damage to the nerves in the area of the injection.
If you receive some relief from the epidural steroid injection, but still have symptoms, the physician may decide to repeat the injection in the next one to three weeks. You are unlikely to benefit from a repeat epidural steroid injection if the first does not offer relief. It is unreasonable to ever undergo more than three injections if none has provided any relief. Even if epidural steroid injections provide relief, only in exceptional cases would more than three injections be justified within a three month period.
If you are getting relief from your injections, but the relief is not permanent, your physician may opt to perform another injection after the effects of the previous injection have worn off. It is unclear how many injections in the epidural space is too many. Some physicians limit the number of injections to four per year. Others on occasion have performed as many as twenty injections in a year without problems. The number of injections which is safe for you to have should be discussed with your physician.
If you have any questions about the procedure or any of the information you just read, please ask Dr. Johnson or his staff. They will be more than happy to answer any questions you may have.
Southwest Sports and Spine, LLC
2001 W. Orange Grove Road #414 Tucson, Arizona 85704
Phone: 520-395-0512 Fax: 520-505-4108