Image-guided procedures are minimally-invasive treatments that are commonly used for diagnostic and pain management purposes. The imaging experts at Mink Radiology perform joint injections (such as epidural and nerve blocks for the spine) and myelography, which provides a real-time look at the movement and structure of the spine.
Areas of Application
Epidural Injections, Nerve Blocks, and Facet Blocks
Each of the vertebrae in our spine is associated with 2 major sensory (touch) and 2 motor (action) nerves, one pair for each side of the body. The human lumbar spine is composed of 5 such vertebrae. These nerves arise from the spinal cord and are contained in a bony and soft tissue space that we refer to as the epidural space. The nerves travel within this bony space from which they exit at different levels; the nerves then descend to our groin, buttocks, legs, and feet. Individuals that have spinal stenosis (narrowing of the bony canal) or disc problems may experience leg and foot pain in addition to back pain.
A typical epidural injection is the delivery of two medications into the space that surrounds the nerves originating in the spine; the purpose of the injection is to provide temporary or prolonged relief from pain and inflammation. Nerve blocks and selective epidural blocks are similar to one another but in these types of injections, only one or two specific nerves are treated.
Facet blocks are injections given into the small joints that line the spine from skull to buttocks; these small joints allow for bending. Just like joints elsewhere in the body, they may become arthritic and be a source of pain and disability. Frequently, multiple joints are treated in one sitting. Steroid drugs, typically a cortisone-like drug and an anesthetic such as xylocaine, are delivered during any of these injections. The injection may reduce pain and swelling in and around the spinal nerve roots or joints which in time may heal. The procedure is NOT intended to remove disc tissue or to realign the spine.
Joint injections, much like epidural or nerve blocks for the spine, may be performed in order to relieve the pain of inflammation. A cortisone-like drug and varying amounts of xylocaine (short-acting pain relief) and marcaine (longer acting) are injected.
Cartilage preserving substances such as Synvisc or Hyalgan are injected to “lubricate” an arthritic joint and relieve pain. Pain relief is never immediate but may take weeks to months to occur. Three injections are typically given, one week apart.
It may be necessary to examine the finest details of a joint, such as the precise state of the lining cartilage or the condition of the labrum (a small structure at the edge of the shoulder and hip joint). The most accurate means of such assessment is to inject a substance known as gadolinium mixed with water. Gadolinium (a rare earth element for those of you who remember high school chemistry) is used to augment an MR procedure and is given by injection halfway through the MR study.
Artificial joints have a greater propensity to become infected than do native joints. In order to determine whether or not a painful artificial (or occasionally non-artificial) joint is infected, an aspiration of the joint is performed. Aspiration refers to the removal of fluid in the joint with subsequent analysis by a laboratory. The fluid examination will help determine the type of antibiotic therapy to be administered if necessary.
Joint Injections Benefits Vs. Risks
- Temporary or prolonged pain relief.
- Temporary or prolonged reduction of inflammation in the region causing pain.
- Better ability to function in daily life without the restrictions previously caused by pain.
The most common “complications” include rapid heartbeat, sleeplessness, and flushing of the skin, especially the face, for 24-48 hours after injection. These side effects are uncomfortable but are not dangerous and do not require treatment.
- Temporary increase in pain, typically for 1-2 hours.
- Headaches are unusual but possible.
The following are very rare complications.
- Infection at the injection site.
- Bleeding if a blood vessel is inadvertently damaged.
- Injury to the nerves at the injection site.
- Temporary paralysis (extraordinarily rare).
How to Prepare for an Epidural or Joint Injection
Most critically, it is absolutely necessary to stop all medications that might potentially increase your tendency to bleed excessively. Aspirin, even “baby doses,” Plavix, and coumadin are the most common medications which have such effects but all anti-inflammatory drugs such as ibuprofen, Celebrex etc should be discontinued, typically for 5 days. It cannot be emphasized enough that such drugs can only be stopped with permission of the physician who prescribed them for you, such as your internist or cardiologist. When scheduling examinations in our office, our staff will remind you of this caveat.
Every patient being considered for the epidural block must have a pre-injection imaging procedure, typically an MR (in some instances, a CT is acceptable) and the study must be brought with the patient (unless it was performed in our office; we store all of our data electronically). It is our very strong preference that the MR be performed in our office since we must review the scan prior to the time of injection. We understand that patients may bring a set of films, or a CD of a recent study from another institution but frequently the CD does not open on our computers, or the studies may not have been performed in a manner that we prefer. Bringing a report only of a prior examination is not acceptable and we will not proceed with the injection. All pre-injection imaging procedures must be no older than 1 year, or it is likely that we will repeat the MR before injection.
Myelography is an imaging examination that involves the introduction of a spinal needle into the spinal canal and the injection of contrast material in the space around the spinal cord (the subarachnoid space) and nerve roots using a real-time form of x-ray called fluoroscopy.
Myelography Benefits Vs. Risks
- Myelography is relatively safe and painless.
- When a contrast material is injected into the subarachnoid space surrounding the spinal nerve roots and spinal cord, it allows the radiologist to view outlines of the different areas of the spine that usually are not visible or distinguishable on x-rays.
- The exam is usually used as an initial study for stroke detection.
- No radiation remains in a patient’s body after an x-ray examination.
- X-rays usually have no side effects when used in the diagnostic range necessary for this procedure.
- There is always a slight chance of cancer from exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. The effective radiation dose from this procedure is about 4 mSv, which is about the same as the average person receives from background radiation in 16 months.
- Although it is uncommon, headaches following myelography from the needle puncture are a risk. If it occurs, a headache usually begins when the patient begins to sit upright or stands. One of the common features of this type of a headache is that it is improved when the patient lays flat. When present, the headache usually begins within 2-3 days after the procedure. Rest while laying on one’s back and increased fluid intake readily relieve mild headaches, but more severe headaches may call for medication. In rare circumstances, some patients may continue to experience spinal headaches, which may necessitate a special, but simple, procedure to stop leakage of cerebrospinal fluid from the puncture site.
- Adverse reactions to the injection of contrast material during a myelogram are infrequent and usually mild in nature, including itching, rash, sneezing, nausea, or anxiety. The development of hives or wheezing is rare but may require treatment with medication. More severe reactions involving the heart or lungs are rare.
- Other rare complications of myelography include nerve injury from the spinal needle and bleeding around the nerve roots as they enter or exit the spinal canal. In addition, the meninges covering the spinal cord may become inflamed or infected. Seizures are a very uncommon complication of myelography.
- There is a very small risk that pressure changes within the spinal canal caused by the introduction of a needle below the site of an obstruction will block the flow of fluid within the subarachnoid space of the spinal canal, which can make urgent surgery necessary.
- Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. Myelography usually is avoided during pregnancy because of the potential risk to the baby.
How to Prepare for a Myelogram
We suggest that patients refrain from large meals prior to injection, but a snack or coffee is permitted. You should inform your physician of any medications you are taking and if you have any allergies to iodinated contrast material. Also, inform your doctor about recent illnesses or other medical conditions. Specifically, the physician needs to know if you are taking medications that need to be stopped a few days before the procedure and whether you have a history of reaction to the contrast material used for the myelogram.
Some drugs should be stopped before myelography. These include certain antipsychotic medications, antidepressants, blood thinners, and other drugs-such as Ultram. The most important type of medication that must be stopped is blood thinners (anticoagulants-baby/aspirin, coumadin, Plavix). If you are taking blood thinners, you should speak with your physician, and if necessary, about alternative methods of maintaining anticoagulation while you are undergoing a myelogram.
Usually, patients are advised to increase their fluid intake the day before a scheduled myelogram, as it is important to be well hydrated. Solid foods should be avoided for several hours before the exam, but fluids may be continued.
You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, eyeglasses and any metal objects or clothing that might interfere with the x-ray images.
Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation.
At the conclusion of the myelogram, the patient is discharged with instructions to be on bed rest for the next 6 hours. You need to arrange to have a relative or friend take you home. Do not plan on driving or working the day of your myelogram. You may restart any medications you were asked to discontinue the next day.Learn More About Pain Management
How are Image-Guided Procedures Performed?
Image-guided procedures are done on an outpatient basis. An injection usually takes only 10 minutes to perform but the patient should expect to be in our facility for 30-45 minutes.
The doctor will identify where the injection should be given and will sterilize the skin with an antiseptic solution. He or she will then inject a local anesthetic to help numb the area before administering the injection. Once the area is numb, the doctor will most likely use imaging guidance to help guide the needle to the exact location.
When the needle is in place, a small amount of a contrast material (x-ray dye) will be injected so the doctor can ensure the distribution of the medication given. Then, your doctor will slowly inject the medication (cortisone, or gadolinium, or Synvisc), or in the case of a suspected infection, will withdraw any fluid that is present. When finished, you will be allowed to leave or to finish the MR examination if necessary.
What to Expect During the Injection
You will feel a brief sting when the local anesthetic is injected under the skin. You may also feel a slight pressure as the needle is inserted. Positioning the needle can occasionally cause a sharp pain. If you feel any sharp pains, however, tell your doctor immediately.
Depending on the amount of swelling in the area, you may experience a burning sensation or some mild discomfort. When the injection is finished, however, any discomfort usually disappears. It is possible to feel “pins and needles” in your legs, depending on the injection site.
Patients having a myelogram may experience headaches, flushing, or nausea may follow contrast injection, though this is rare. Seizures are also possible but are very rare with the newer contrast materials that we use.
It is recommended that you take it easy for the rest of the day. You may resume normal activities the next day. Please refer to the post-injection instructions that you will receive.
Next, learn about magnetic resonance imaging.