In many cases of chronic back pain, spinal injections may be used both to find out what is causing your pain and to treat your pain. Doctors refer to these two separate uses of spinal injections as diagnostic and therapeutic. 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. Injections are also therapeutic in that they can provide temporary relief from pain.
Learn about spinal injections including:
- What medications are injected?
- What types of injections are used?
- Why might you choose to have an injection?
- Why might you choose not to have an injection?
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. That is why lidocaine is used more often as a diagnostic tool rather than a long-lasting pain reliever. Bupivacaine (also known as Marcaine) is another type of anesthetic that can be used. It is slower to take effect, but it lasts longer, giving the patient more relief from pain.
Cortisone is a strong anti-inflammatory steroid medication. It is commonly injected along with a local anesthetic 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 not begin working for several days following the injection, but the effects can last for months. Sometimes a narcotic medication such as morphine or fentanyl is mixed with cortisone and the anesthetic to get increased pain relief.
Epidural Steroid Injection (ESI)
An ESI is a common type of injection that is given to provide relief from certain types of low back and neck pain. The "epidural space" is the space between the covering of the spinal cord (dura mater) and the inside of the bony spinal canal. It runs the entire length of your spine. When 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 near the area of injection. For example, if the injection is given in the lumbar spine, the medication will usually affect the entire lower portion of the spine.
The epidural needle is inserted into the back until the doctor feels sure it is in the epidural space. The doctor will then place a small amount of lidocaine into the epidural space and wait to see if you feel warmth and numbness in your legs. If so, the needle is most likely in the correct position. The remainder of the medication is injected and the needle is withdrawn.
There are three different ways to perform an epidural injection:
- caudal block
A caudal block is placed through the sacral gap (a space below the lumbar spine near the sacrum). The injection is placed into the epidural space. This type of block usually affects the spinal nerves at the end of the spinal canal near the sacrum. This collection of nerves is called the cauda equina. One of the benefits of this type of injection is less chance of puncturing the dura.
The translumbar approach is the most common way of performing an epidural injection. This type of injection is performed by placing a needle between two vertebrae from the back. The needle is inserted between the spinous processes of two vertebrae. You can actually feel the bumps that make up the spinous process by feeling along the back of your spine.
The transforaminal approach is a very selective injection around a specific nerve root. The foraminae are small openings between your vertebrae through which the nerve roots exit the spinal canal and enter the body. By injecting medication around a specific nerve root, the doctor can determine if this nerve root is causing the problem. This type of epidural injection is used most often for diagnostic purposes, and it is commonly used in the neck.
Facet Joint Injections
Facet joint injections are used to localize and treat low back pain 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 a facet joint is causing the pain. The medication used also decreases inflammation that occurs in the joint from arthritis and joint degeneration.
It is important to make sure that the injection goes directly into the facet joint. Fluoroscopy can be used to confirm that the needle is in the right position before any medication is injected. A fluoroscope uses X-rays to show a TV image. You doctor can watch on the screen as the needle is placed into the joint and magnify the image to increase accuracy.
There are two types of facet joint injections.
- Interarticular are injected directly into the joint to block the pain and reduce inflammation.
- Nerve blocks help determine whether the joint is indeed a source of pain by blocking the small nerves that connect with the joint.
A facet joint injection is perhaps the best way to diagnose facet joint syndrome. Joints that look abnormal on an X-ray may in fact be painless, while joints that look fine may actually be a source of pain. This is a rather simple procedure with little risk.
Your doctor may need to determine whether the metal hardware that has been used during surgery could be causing your discomfort. A hardware injection is performed by injecting lidocaine alongside the spinal hardware that was placed in the spine during surgery. If the pain is removed temporarily by the injection, it may indicate that the hardware is causing your pain.
These injections are used to determine whether a specific piece of hardware is causing the pain and needs to be removed surgically.
SI Joint Injections
Sacroiliac (SI) joint pain is easily confused with back pain from the spine. The SI joint is located between the sacrum and pelvic bones. Sometimes injecting the SI joint with lidocaine may help your doctor determine whether the SI joint is the source of your pain. 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. Cortisone is added to treat inflammation from SI joint arthritis. The injection usually gives temporary relief for several weeks or months.
SI joint injections can be used both to treat pain and to determine the source of the pain. This injection usually requires the use of fluoroscopic guidance or a CT scan in order to make sure the needle is placed correctly in the joint.
Differential Lower Extremity Injections
Various types of injections into certain areas of the lower extremities can help your doctor decide where the pain is starting. Pain that comes from problems with the back and the spinal nerves can mimic many other conditions. Sometimes it is impossible to tell if the pain you are experiencing is due to a back condition or a problem in your hip, knee, or foot.
To help determine whether a joint of your lower limb is causing you pain, your doctor may suggest injecting medication, such as lidocaine, into the joint to numb the area. Once the medication is injected, if the pain goes away immediately, that joint is more likely to be the source of the pain than your back. Your doctor can then focus on finding the problem in the joint.
When certain medical conditions are present, doctors may determine it is unsafe to perform a spinal injection. Your doctor will discuss any concerns with you before making a final decision.
If you have a tendency to heavy bleeding or are on anti-coagulant therapy (medication that prevents blood clotting), you are not a good candidate for spinal injections. The physician might ask you to 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 procedure.
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 (inflammation in the covering that surrounds the spinal cord). Make sure to 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 offered to patients without life-threatening conditions. A medically unstable patient should have his or her medical condition treated before any elective injections are given.
Consider these basic warnings before choosing to have a spinal injection.
- If you are chronically taking a platelet-inhibiting drug, such as aspirin or NSAIDs (non-steroidal 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 the drugs used in the injection. Make sure to 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 instance, 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 due to the effects of fluid retention several days after an injection.