Your doctor may suggest that an epidural injection not be considered if you have abnormalities of the epidural space. Either it has been altered from a congenital (present at birth) abnormality, or from a previous surgery that has left scarring.
Injecting steroids, such as cortisone, anywhere in the body allows for absorption of the medication into the bloodstream and can lower the body's ability to fight infections. Cortisone should not be used if there is any type of serious infection in the body.
Absorption of the medication may also cause a systemic (whole body) corticosteroid effect such as fluid retention or interference with glucose control. An epidural might not be appropriate for patients with diabetes or congestive heart failure.
There are risks associated with epidural injections. This is not intended to be a complete list, but these are some of the most common.
- dural puncture
- intravascular injection
- bladder dysfunction
- neurologic complications
A dural puncture, or "wet tap," is perhaps the most common complication from an ESI. This complication only occurs in 0.1 to 5 percent of all injections. The result of a dural puncture is usually a spinal headache and nausea. A spinal headache occurs when the puncture in the spinal sac fails to seal itself off. This allows the spinal fluid to continue to leak out and lowers the spinal fluid pressure in the brain. When sitting or standing, the headache and nausea are much worse because the spinal fluid pressure is lower at the top (near your head) than at the bottom of the spine. The headache usually goes away when you lie down with your feet higher than your head.
To treat a spinal headache, a "blood patch" is usually recommended. If the doctor realizes immediately during the procedure that there is a wet tap, he may perform a blood patch before he removes the epidural needle. A blood patch is a simple procedure. About three ounces of blood are drawn from an arm vein and immediately injected into the epidural space with the epidural needle. The blood clots around the spinal sac and stops the leak by forming a "patch."
There is a slight chance that the medication may be injected into one of the tiny blood vessels that runs through the epidural space instead of the epidural space itself. This can cause seizures, cardiac arrest, and even death if too much of the medication goes directly into the blood steam. The chance of this happening is very small. Your doctor can discuss it with you in further detail.
Epidural injections are done under sterile conditions very similar to surgery. Still, anytime a needle is inserted into the body there is a small chance of infection. Since the needle must be placed near the spine during an epidural, an infection is much more serious if it occurs. The chance that an infection will occur is extremely small.
An epidural injection can result in a hematoma. A hematoma is simply a collection of blood caused by an injury to a blood vessel. An epidural hematoma can be serious if it is big enough to put sufficient pressure on the spinal nerves so that they quit working. This can cause problems with the bowels and bladder.
The epidural injection actually paralyzes the nerves to the bowel and bladder for a short period. You may not have control over your bladder for one to two hours following the procedure.
There is always a small risk of damage to the spinal nerves. The spinal cord is a bundle of millions of nerves connecting the brain with the rest of the body. If the epidural needle directly injures the spinal nerves, it may result in injury to the nerves.