Epidural steroid injections (ESIs) are a common treatment option for various forms of back and leg pain. If you or a patient suffers from sciatica and low back pain, you may have encountered this form of relief. So, how exactly does this work?
- The patient is positioned by the
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- The skin in the low back area is cleaned and then numbed with a local anesthetic similar to what a dentist uses.
- Using fluoroscopy (live X-ray) for guidance, a needle is inserted into the skin and directed toward the epidural space. Fluoroscopy is considered important in guiding the needle into the epidural space, as controlled studies have found that medication is misplaced in many (> 3of epidural steroid injections that are done without fluoroscopy.
- Once the needle is in the proper position, contrast is injected to confirm the needle location. The epidural steroid solution is then injected. Although the steroid solution is injected slowly, most patients sense some pressure due to the amount of the solution used (which in lumber injections can range from 3mL to 10mL, depending on the approach and steroid used). The pressure of the injection is not generally painful.
- Following the injection, the patient is monitored for 15 to 20 minutes before being discharged home.
What's in the ESI solution?
ESIs are delivered directly into the epidural space in the spine. The epidural space encircles the dural sac and is filled with fat and small blood vessels. The dural sac surrounds the spinal cord, nerve roots, and cerebrospinal fluid (the fluid that the nerve roots are bathed in).
Sometimes additional fluid (local anesthetic and/or a normal saline solution) is used to help 'flush out' inflammatory mediators from around the area that may be a source of pain. Although these injections are considered a temporary relief (giving pain relief from a week to one year), an epidural can be very beneficial for a patient during acute episodes of back or leg pain.
Typically, a solution containing cortisone (steroid) with local anesthetic (lidocaine or bupivacaine), and/or saline is used.
- A steroid, or cortisone, is usually injected as an anti-inflammatory agent. Inflammation is a common component of many low back conditions and reducing inflammation helps reduce pain. Triamcinolone acetonide, Dexamethasone, and Methylprednisolone acetate are commonly used steroids.
- Lidocaine (also referred to as Xylocaine) is a fast-acting local anesthetic used for temporary pain relief. Bupivacaine, a longer lasting medication, may also be used. Although primarily used for pain relief, these local anesthetics also act as 'flushing' agents to dilute the chemical or immunologic agents that promote inflammation.
- Saline is used to dilute the local anesthetic or as a 'flushing' agent to dilute the chemical or immunologic agents that promote inflammation.
Who shouldn't receive ESIs
Several conditions could preclude a patient from having an injection:
- Local or systemic infection
- Pregnancy (if fluoroscopy, a type of X-ray, is used)
- Bleeding problems - patient taking blood thinners (Coumadin, etc), or patients with a bleeding problem (hemophilia, etc)
Epidural steroid injections should also not be performed on patients whose pain could be related to a spinal tumor. If suspected, an MRI scan should be done prior to the injection to rule out a tumor.
Injections may be done, but with caution, for patients with other potentially problematic conditions such as:
- Allergies to the injected solution
- Uncontrolled medical problems such as renal disease, congestive heart failure and diabetes because they may be complicated by the fluid retention that a small percentage of patients experience for a few days after the injections.
Use of high dose aspirin or other anti-platelet drugs (e.g. Ticlid, Plavix), all of which can cause bleeding from the procedure. These medications should be stopped prior to having an injection.