What is an epidural steroid injection?
Several common conditions, including a lumbar disc herniation, degenerative disc disease, and spinal stenosis, can cause severe acute or chronic low back pain and/or leg pain. 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 the tear is near the spinal canal, the bulging disc can put pressure on the spinal cord and nerve roots. Spinal stenosis is a narrowing of the spinal canal that can cause pressure on the spinal cord and spinal nerves. In these conditions, spinal nerves can become inflamed due to irritation or compression, which results in the pain that many patients experience.
Depending on which part of the spine the inflamed nerves are located in, pain and/or other symptoms (such as numbness or tingling) may be experienced in different areas of the body:
- Nerve irritation in the cervical spine can lead to pain, tingling, or numbness in the neck, shoulder, or arm.
- Nerve irritation in the thoracic spine can lead to upper back pain, pain along the ribs and chest wall, and rarely pain in the abdomen.
- Nerve irritation in the lumbar spine can lead to lower back, hip, or buttock pain, or pain, numbness, or tingling in the leg.
An epidural steroid injection involves the administration of a long acting medicine (corticosteroid) directly at the site of the pathology in order to reduce inflammation in that region. When steroids are injected into the epidural space, they do not directly touch the spinal cord. Instead, they reduce the inflammation on the tissue covering the nerves and the spinal cord. The ultimate goal is to reduce pain, numbness and tingling caused by nerve irritation. It is important to remember that an epidural steroid injection will not correct the preexisting medical problem (such as spinal stenosis, a herniated or bulging disc, etc.), but should improve the level of pain associated with that condition.
What is the epidural space?
A membrane called the dura mater covers the spinal cord and the nerves that leave the spinal cord and run towards different parts of the body. Around the dura is a space called the epidural space. Before nerves can travel from the spine into the arms, chest, and legs, they travel through the epidural space, and exit through small nerve holes. During an epidural steroid injection, medication is injected directly into the epidural space.
Is the injection painful?
An epidural injection is often tolerated very well. A local anesthetic is given on the skin which may feel like a small bee sting and last only for a few seconds. Some patients may feel pressure from the medicine as it is being injected into the epidural space. This is well tolerated by our patients. The pace of medicine injection is carefully monitored to limit the pressure buildup in the back.
Do I need anesthesia for this procedure?
Epidural injections are often performed without additional intravenous sedation. However, intravenous sedation is available for those patients that require or request it. The medications used for intravenous sedation include Versed (a Valium-like drug) and Fentanyl (a Morphine-like drug). These medications are commonly used for sedation during medical procedures and are well tolerated by most patients.
How is the injection performed?
- First, patients are brought to the radiology suite by a nurse and technologist and placed on their stomach for the procedure. The skin of the back will then be well cleaned with betadine or alcohol.
- An IV is started so that medicine can be given for relaxation if desired. Sedation is available for patient anxiety and comfort. However, sedatives are rarely necessary, as the epidural steroid injection procedure is usually not uncomfortable. If a sedative is used, the patient will need to be monitored for a longer period following the injection.
- The area where the epidural needle will be inserted is numbed with a local anesthetic.
- A small needle will then be directed into the epidural space using fluoroscopy for guidance. The patient will feel some pressure during this part of the procedure. The x-rays are important to help ensure correct placement of the medications. Studies have found that medication is misplaced in 13-34% of epidural steroid injections that are done without fluoroscopy.
- Once the needle is in place, dye is injected to confirm that the medicine spreads to the affected nerve(s) in the epidural space.
- A combination of numbing medicine (an anesthetic) and time released anti-inflammatory medicine (a steroid) is injected.
Will I have any restrictions after the injection?
It is expected that all patients will be driven to and from their appointment for an epidural steroid injection. Regular medicines may be taken after an epidural steroid injection. Most patients can walk around immediately after the procedure. However, we advise all of our patients to take it easy for a few days and not “push it”, even if they are feeling better. When the pain has improved, regular exercise may be resumed in moderation. Even if improvement is significant, activities should be increased slowly over one to two weeks to avoid a recurrence of pain.
What can I expect after the injection?
The initial response to the injection may be heaviness and tingling of the legs. You may also experience significant pain relief. This is due to the local anesthetic mixed with the corticosteroid. Pain may return within a few hours, after the local anesthesia wears off but before the steroid has had a chance to work. In addition, there can be some discomfort in the area of the injection due to irritation from the needle itself as well as an initial response to the corticosteroid. This should only last for 24-48 hours. Ice packs may help reduce the inflammation and will typically be more helpful than heat during this time. Improvements in pain will generally occur within 3-5 days after the epidural injection but may be noticed sooner.
Epidural steroid injections help to relieve pain in approximately 50% of patients. These effects tend to be temporary; we have seen positive results lasting from just a few days to many months. The overall effectiveness of an epidural steroid injection is often related to the cause of the back pain. Patients with disk-related pain tend to do well while patients with structural spine problems (such as spinal stenosis) tend to have poorer response rates. In addition, length of time that the patient has been experiencing symptoms tends to influence outcome as well. The injections are slightly less effective in patients who have been experiencing pain for a longer period of time. The few studies that have looked at long-term pain relief after an epidural steroid injection have shown that 50% of patients who initially responded to the injection will have recurrent pain after 12 months.
Importantly, an epidural steroid injection can provide the pain relief that is needed to allow a patient to progress with their rehabilitation program. Long-term improvement can often be obtained when epidural steroid injections are followed by appropriate forms of physical therapy. Individuals who have less back pain and feel more comfortable are generally able to work on the therapy that is critical to rehabilitate the lower back and prevent or minimize future episodes of lower back pain (including stretching, strengthening/pain relief exercises and low impact aerobic conditioning).
How come I am being scheduled for a series of injections?
In some patients, the pain relief after an epidural steroid injection will be permanent. In others, the pain will be lessened enough to allow the patient to progress with rehabilitation and exercise, which helps the patient heal and find pain relief on a long-term basis. If excellent pain relief is obtained from the first epidural injection, there will be no need to repeat it. If there is a partial benefit (greater than 30% relief from pain) the epidural injection can be repeated for possible additional benefit, or it may be necessary to conduct additional tests to more accurately determine what is causing the patient’s pain. It has been shown that results tend to improve and become more long lasting with “overlapping” doses of steroids. Up to three epidural steroid injections may be performed within a one-year period, as long as they are spaced at least 2-4 weeks apart. Injections performed more frequently can increase the risk of corticosteroid side effects. If the initial injection provides minimal benefit (less than 30% pain relief) the physician may either repeat the injection, or try a different type of injection or treatment.
Who should not have an epidural steroid injection?
Lumbar epidural steroid injections should not be performed on patients who have a local or systemic bacterial infection, are pregnant (if fluoroscopy is used) or have bleeding problems. Epidural injections should also not be performed for patients whose pain is from a tumor or infection, and if suspected, an MRI scan should be done prior to the injection to rule out these conditions. Injections may be done, but with extreme caution, for patients with allergies to the injected solution, uncontrolled medical problems (such as congestive heart failure and diabetes. In diabetic patients, a steroid injection may slightly elevate blood sugar levels, especially during the first 24 hours. If you are taking Aspirin, Plavix, or blood thinning medication, you may need to stop taking it several days before an epidural steroid injection. Discuss any medications with your doctors, including the doctor who prescribed them and the doctor who will perform the injection.), and those who are taking aspirin or other antiplatelet drugs such as Plavix.
What are the risks of epidural steroid injections?
The procedure is generally very safe but as with all invasive medical procedures, there are potential risks. The potential risks include the following:
- Infection. This is rare because these injections are performed under sterile conditions. Minor infections occur in 1% to 2% of all injections. Severe infections are rare, occurring in 0.1% to 0.01% of injections.
- Bleeding. A rare complication, bleeding is more common for patients with underlying bleeding disorders. An epidural hematoma can form if blood vessels in the epidural space are injured during the procedure. This can be serious if it is big enough to put sufficient pressure on the spinal nerves so that they stop working.
- Nerve damage. While extremely rare, nerve damage can occur from direct trauma from the needle, or secondarily from infection or bleeding.
- Dural puncture. This occurs in 0.5% of injections and results in 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. The headache usually goes away when you lie down with your feet higher than your head. To treat this, a blood patch may be recommended. This involves drawing a small amount of blood from an arm vein and immediately injecting it into the epidural space with the epidural needle. The blood clots around the spinal sac and stops the leak by forming a "patch."
- For a lumbar epidural injection, paralysis is not a risk since there is no spinal cord in the region of the epidural steroid injection.
- Steroid Side Effects (2%). These include transient flushing with a feeling of warmth (‘hot flashes’) for several days, fluid retention, weight gain, or increased appetite, elevated blood pressure, mood swings, irritability, anxiety, insomnia, high blood sugar (diabetic patients should inform their primary care physicians about the injection prior to their appointment), transient decrease in immunity, cataracts (a rare result of excessive and/or prolonged steroid usage), and severe arthritis of the hips or shoulders.
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