Spinal Injections
 
Introduction

In many cases of chronic back pain, spinal injections are used both to learn more about what is causing your pain and to treat your pain. Health care providers refer to these two separate uses of spinal injections as diagnostic and therapeutic. The injections can be a diagnostic tool because they give your doctor information that helps him or her make a diagnosis. For example, if an injection provides pain relief in the area that is injected, it is likely that this particular area is the source of the problem. Once the location of one or more sources of pain is discovered, your health care provider can perform other necessary tests to try to determine the actual problem and create the proper treatment plan. The injections are therapeutic in that they can provide temporary treatment and temporary relief from pain.


This document will address the following information about spinal injections:

What Medications Are Injected and Why

With most spinal injections, a local anesthetic (numbing medication) called lidocaine (also known as Xylocaine) is injected into a specific area of the spine. Lidocaine is a fast-acting drug, but the effects wear off within about two hours. Therefore, this medication is used more as a diagnostic tool than a long-lasting pain reliever. Another type of anesthetic, called Bupivacaine (also known as Marcaine), can also be used. This anesthetic takes longer to take effect, but it also wears off slower, giving the patient more relief from pain.

A strong anti-inflammatory steroid medication, cortisone, is also commonly injected along with one of the above anesthetics in order to reduce inflammation in the affected areas. Cortisone is long lasting and can be slow releasing in order to give the best possible benefits of pain relief. Cortisone may take several days to begin working to reduce inflammation following injection, but the effects can last for months. In some cases, a narcotic medication such as morphine or fentanyl may be mixed with the cortisone and the anesthetic to get better pain relief from the injection.


Types of Injections and Why They Are Done 

Epidural Steroid Injection (ESI)

An ESI is a common type of injection that is given to provide relief from low back pain and from certain types of neck pain. The "epidural space" is the space between the spinal sac (called the dura mater) and the inside of the bony spinal canal. It runs the entire length of your spine. Once injected into this area, the medication moves freely up and down the spine to coat the nerve roots and the outside lining of the facet joints of the spine near the area of injection. For example, if the injection is done in the lumbar spine, the medication will usually affect the entire lower portion of the spine.

Some reasons not to use epidurals:

  • Technical Reasons - Your health care provider may suggest that an epidural injection not be considered if you have abnormalities of the epidural space; it has been altered from a congenital (present at birth) abnormality or from previous surgery that has left scarring.

  • Infection - 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.

  • Steroid-Related - Absorption of the medication may also cause a whole body (systemic) corticosteroid effect such as fluid retention or interference with glucose control. Therefore, an epidural might not be well suited for patients with diabetes or congestive heart failure.

Risks

With any surgery, there is a risk of complications. When surgery is done near the spine and spinal cord these complications (if they occur) can be very serious. Complications could involve subsequent pain and impairment and the need for additional surgery. You should discuss the complications associated with surgery with your doctor before surgery. The list of complications provided here is not intended to be a complete list of complications and is not a substitute for discussing the risks of surgery with your doctor. Only your doctor can evaluate your condition and inform you of the risks of any medical treatment he or she may recommend.

There are several risks involved with epidural injections to be aware of:

  • Dural Puncture - 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, 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 he has a wet tap, he may perform a blood patch before he removes the epidural needle. A blood patch is a simple procedure where about three ounces of blood are drawn from an arm vein. The blood is then immediately injected into the epidural space with an epidural needle. The blood then clots around the spinal sac and stops the leak by forming a "patch".

  • Infection - 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 in an epidural is going near the spine, an infection is much more serious if it occurs. The chance that an infection will occur is extremely small.

  • Bleeding - An epidural injection can result in a hematoma. A hematoma is simply a collection of blood due to an injury to a blood vessel. An epidural hematoma can be serious if it is big enough to cause enough pressure on the spinal nerves so that they quit working. This can cause problems with the bowels and bladder.

  • Neurologic Complications - There is always a small risk of damage to the spinal nerves. The spinal cord is a bundle of millions of nerves that connects the brain with the rest of the body. If the epidural needle directly injures the spinal nerves, this can cause neurologic problems.

Facet Joint Injections

Facet joint injections are used to localize and treat low back pain that is caused by problems of the facet joints. These joints are located on each side of the vertebrae; they join the vertebrae together and allow the spine to move with flexibility. The facet joint injections form a pain block that allows the doctor to confirm that it is a facet joint causing the pain. The medication used also decreases inflammation of the joint that occurs with arthritis and joint degeneration.

To insure that an injection is actually into the facet joint, "fluoroscopy" can be used to confirm that the needle is in the right position before the medication is injected. A fluoroscope uses X-rays to show a TV image, so the doctor can watch as the needle is placed into the joint. The fluoroscope can also magnify the image, increasing accuracy.

There are two types of facet joint injections:

  1. Interarticular - This is injected directly into the joint to block the pain and reduce inflammation.

  2. Nerve Blocks - These help determine whether the joint is indeed a source of pain by blocking the medial branch or nerves that connect with the joint.

Indications to use a facet joint injection

A facet joint injection is perhaps the best way to diagnose facet joint syndrome. Joints that may look abnormal on an X-ray may in fact be painless, and joints that look fine may indeed be the source of the pain - only the injection tells the true story. These injections may be used to treat low back pain and determine whether the facet joints are the true culprits. It is also a rather simple procedure with low risk.


Sacroiliac Joint Injections

Sacroiliac joint (SI joint) pain is easily confused with back pain from the spine. The SI joint is located between the sacrum and the hipbone. In some cases, injecting the SI joint with lidocaine may help your doctor determine whether it is the source of your pain or not. If the joint is injected and your pain does not go away, it is probably coming from somewhere else. If the pain goes away immediately, your doctor may also inject cortisone into the joint before removing the needle. The cortisone is added to treat the inflammation from SI joint arthritis that may be causing your pain. The injection usually gives temporary relief for several weeks or months.

Indications to use a sacroiliac joint injection

SI joint injections can be used to treat and to prove that the SI joint is the source of pain. This injection usually requires the use of fluoroscopic (radiologic) guidance or a CAT scan in order to make sure the needle is placed correctly in the joint. CAT scans are X-ray tests that produce X-ray "slices" taken of the spine, so each section can be examined separately. 


General Contraindications to Blocks and Injections

Some basic reasons not to have spinal injections are:

  • Bleeding Tendencies - If you have a tendency to heavy bleeding or are on anticoagulant therapy (taking a medication that prevents blood clotting), you are not a good candidate for spinal injections. The physician giving the injection may ask that you stop all medications such as aspirin and ibuprofen five days before the injection. These medications can decrease the ability of the blood to clot and lead to problems. Make sure your provider has a list of your medications well ahead of your scheduled time for injection.

  • Infections - If you have a local or systemic infection, a spinal injection may put you at greater risk for spreading the infection into the spine causing meningitis. Make sure you tell your health care provider if you have any infected wounds, boils, or rashes anywhere on your body.

  • Unstable Medical Conditions - Injections are usually an elective procedure that is offered to patients without life-threatening conditions. A medically unstable patient should have their medical condition treated before any elective injections are given.


General Precautions - The following are basic warnings to consider before choosing to have a spinal injection:

  • If you are chronically taking a platelet-inhibiting drug, such as aspirin or NSAIDs (nonsteroidal anti-inflammatory drugs), you have an increased risk of bleeding and might not be a candidate for a spinal injection.

  • If you are hypersensitive or have certain allergies to medications, you may have a negative reaction to drugs used in the injection. Make sure you give your provider a list of your allergies.

  • If you have an accompanying medical illness, you should discuss the risks of spinal injections with your physician. For example, patients with diabetes mellitus might experience an increase in blood sugar after an injection with cortisone. Patients with congestive heart failure, renal failure, hypertension, or a significant cardiac disease may have problems because of the effects of fluid retention several days after an injection.