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Spinal Injections

Introduction

In many cases of chronic back pain, your doctor may recommend a spinal injection. A spinal injection may be done to find out what is causing your pain. It may also be used 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.

Medications

With most spinal injections, a local anesthetic (numbing medication) called lidocaine (also known as Xylocaine) is injected into a specific area of your 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 you 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 provide increased pain relief.

There are several different types of spinal injections your doctor may recommend depending upon the nature and location of your pain.

Preparations

You will probably be asked to arrive early to fill out paperwork and answer some questions. Your doctor will want to verify that you are ready for the procedure. You may be asked to come in "NPO". This means you should not have anything to eat or drink for at least six hours before the procedure. This reduces the risk of vomiting food or liquids if you should become nauseated or have a reaction to the medications. Nausea is unpleasant, but it can also cause serious complications if you accidentally inhale (aspirate) food or liquid into your lungs while you are groggy. Not having anything in your stomach during this procedure is an extra precaution highly recommended by most doctors.

You will probably be asked to change into a hospital gown. You will then be connected to a device that monitors your heart rate (pulse) and blood pressure. An intravenous (IV) line may be started in your arm. You may be asked to sit on a stretcher or lie on your side for the procedure. The area of your back will be prepared with an antiseptic. Lidocaine may be injected to numb your skin around area where the injection will be given.

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 your 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 your spine to coat the nerve roots and the outside lining of your facet joints near the area of the injection. For example, if the injection is given in your lumbar spine, the medication will usually affect the entire lower portion of your spine.

Epidural injections are used to treat radicular pain caused by nerve irritation. This type of pain is usually caused by herniated discs or spinal stenosis. A herniated disc occurs when pressure or degeneration produces a tear in the disc's outer ring (the annulus), and the nucleus ruptures out of its normal space. If it rips near the spinal canal, the bulging disc can push out of its space and into the spinal canal, placing inappropriate pressure on your spinal cord and nerve roots. Spinal stenosis is a narrowing of the spinal canal that can cause pressure on your spinal cord and spinal nerves.

Epidural injections are also helpful when your main problem is arthritis of the facet joints in multiple areas of your spine. The medication coats the outside of the problem joints and absorbs into the joints of your spine. This type of injection reduces the inflammation in the joint. The injection is sometimes aimed at the small nerves that supply the joints.

It may be necessary to have several epidural injections in a series over a period of a few weeks. This is because the relief from the epidural injection usually decreases with time. It is not uncommon to have three lumbar epidural injections, each about ten days apart.

During the ESI procedure, an epidural needle is inserted into your back and into the epidural space. Your doctor will then place a small amount of lidocaine into the epidural space and wait to see whether 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 an ESI placed through the sacral gap (a space below your lumbar spine near your sacrum). The injection is placed into the epidural space. This type of block usually affects the spinal nerves at the end of your 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.

Translumbar

The translumbar approach is the most common way of performing an ESI. This type of injection is performed by placing a needle between two vertebrae from your 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.

Transforaminal

The transforaminal approach is a very selective type of ESI around a specific nerve root. The foraminae are small openings between your vertebrae through which the nerve roots exit your spinal canal and enter your body. By injecting medication around a specific nerve root, your doctor can determine whether this nerve root is causing your problem. This type of ESI is used most often for diagnostic purposes, and it is commonly used in the neck.

Facet Joint Injection

A facet joint injection is used to localize and treat low back pain caused by problems with your facet joints. These joints are located on each side of the vertebrae in your spine. They join the vertebrae together and allow your spine to move with flexibility.

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. If the facet joint injection blocks the pain, your doctor is able to confirm that the problem is with the facet joint that was injected. The medication used also decreases inflammation that occurs in the joint from arthritis and joint degeneration.

When performing a facet joint injection, it is important to make sure that the injection goes directly into the facet joint. Your doctor may use fluoroscopy 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 your joint and magnify the image to increase accuracy.

There are two types of facet joint injections.

  • Interarticular injected directly into the joint to block the pain and reduce inflammation.
  • Nerve block to help determine whether the joint is indeed a source of pain by blocking the small nerves that connect with the joint.

Hardware Injections

If you had spinal surgery that included the use of metal hardware such as screws or rods and you are now experiencing spinal pain, your doctor may need to determine whether the metal hardware that was used during surgery could be causing your discomfort. A hardware injection is performed by injecting lidocaine alongside the spinal hardware that was placed in your spine during surgery. If the pain is temporarily relieved by the injection, it may indicate that the hardware is causing your pain.

SI Joint Injections

Sacroiliac (SI) joint pain is easily confused with back pain from the spine. Your SI joint is located between your sacrum and pelvic bones. Sometimes injecting the SI joint with lidocaine may help your doctor determine whether your SI joint is the source of your pain. If the joint is injected and your pain does not go away, your pain is probably coming from somewhere else. But if your pain goes away immediately, this indicates your SI joint is the problem. In that case, 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 your lower extremities can help your doctor find the cause of your pain. Pain that comes from problems with your back and your spinal nerves can mimic many other conditions. Sometimes it is impossible to tell whether 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, such as your knee or hip, 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.

Risks Associated with Spinal Injections

General

In general, when certain medical conditions are present, your doctor may decide 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. Your doctor might ask you to stop all medications such as aspirin and ibuprofen five days before the injection. These medications can decrease the ability of your blood to clot and may lead to problems. Make sure your doctor has a list of your medications well ahead of your scheduled procedure.

If you have a local or systemic (whole body) infection, a spinal injection may put you at greater risk for spreading the infection into your spine, causing meningitis (inflammation in the covering that surrounds your spinal cord). Make sure to tell your doctor if you have any infected wounds, boils, or rashes anywhere on your body.

Spinal 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.

ESI-specific Risks

Your doctor may recommend you not have an ESI if you have abnormalities in the epidural space of your spine. Such abnormalities could be congenital (present at birth) or from a previous surgery that has left scarring. Your doctor may also recommend against an ESI if you have an infection. Injecting steroids, such as cortisone, anywhere in your body allows for absorption of the medication into your bloodstream and can lower your body's ability to fight infections. Cortisone should not be used if there is any type of serious infection in your body. Absorption of the medication may also cause a systemic corticosteroid effect such as fluid retention or interference with blood glucose control. An epidural might not be appropriate for patients with diabetes or congestive heart failure.

General Precautions

Consider these basic warnings before choosing to have a spinal injection:

  • If you regularly take 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 doctor a list of all your allergies.
  • If you have an accompanying medical illness, you should discuss the risks of spinal injections with your doctor. 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.

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