How does an Epidural Steroid Injection work?
Epidural Steroid Injection (ESIs) are commonly used to help control back and neck pain by reducing inflammation and swelling around the spine and nerves.
Steroid injections are performed to diminish symptoms of radicular pain (pain radiating down an arm or leg) or Spinal Stenosis.
Steroid injections are for temporary relief of pain; they are not a cure. Pain relief often lasts from a couple of weeks to months. There are rare but serious risks involved.
During the ESI procedure you will be lying on your abdomen with a pillow under the pelvis or a ramp with a head support. A pillow will be placed under your lower legs for comfort.
The translaminar ESI is performed using fluoroscopy to guide the placement of a small needle between two vertebra into the epidural space. Placement is confirmed with a small amount of iodinated contrast or dye. Then the steroids are injected into the area. Anesthetics are placed in the lumbar region with the steroids, giving short term pain relief (usually 1-6 hours). The steroids generally work in 24-72 hours and last 2 weeks to several months, depending on the person.
A caudal injection is performed in the same fashion as a conventional ESI but is very low in the vertebral column. A small needle is placed in opening at the tip of the sacrum, which has a direct connection to the epidural space. Steroids and analgesics placed in this area move upward to bathe the nerves in the lower back.
Complications are rare but can include but are not limited to: headache, damage to nerve roots or spinal cord, bleeding, infection, allergic reaction or steroid induced reactions.
Location of ESIs
There are two openings in the spine where a needle can be inserted for the ESI. These consist of: Translaminar and Caudal. The ESIs can be performed in the cervical, thoracic and lumbar areas.
Steroids are an anti-inflammatory medication that when injected into the epidural works on the nerves, nerve roots, disc spaces, and connective tissue to decrease the inflammation. When inflammation is reduced it allows the nerves to work better and decreases pain, numbness and tingling.
If a specific nerve is actually the cause of pain the local anesthetic in the injection will give immediate relief. The steroids in the injection will reduce inflammation over the next few days and possibly provide relief of pain that lasts for weeks to months. Herniated disk in the lumbar spine causing low back pain with leg pain (sciatica) is a common condition treated by a selective nerve root block.
There are rare but serious risks involved in a selective nerve root block, as in any spinal injection, as well as the possibility of side effects from corticosteroids.
Side effects from corticosteroids may also occur though long-term systemic side effects are unlikely as only a small amount of corticosteroids enters the bloodstream.
Risks / Complications / Side Effects of Spinal Injections
Some possible risks of a spinal injection are dural puncture, infection, bleeding, allergic reaction, arachnoiditis, worsening of pain, nerve damage or spinal cord damage, paralysis, or death. Catastrophic complications are extremely rare, e.g. paralysis or death.
The resulting reduction of cerebrospinal fluid pressure may cause a spinal headache. Spinal Headaches tend to worsen upon standing and improve when lying down. The headache usually resolves within a few days but can last longer. Most cases eventually resolve by pushing fluids with salt and caffeine without treatment. Rarely, a persistent spinal fluid leak develops which may be treated with a blood patch. A small amount of a person’s own blood can be injected into the epidural space, where it will clot and usually seal the leak.
Infection: Minor infections occur in less than two percent of injections. Serious Infections / Epidural Abscesses are rare. Diabetics are at a higher risk of infection.
Bleeding / Epidural Hematoma: An epidural hematoma is a large pocket of blood that accumulates in the epidural space when bleeding continues after injury of epidural vein. This can compress the spinal cord and cause permanent damage if not treated quickly. Patients taking blood-thinners need to be evaluated prior to injections. In most cases thinners are held to normalize blood clotting for the procedure. This is a rare complication.
Allergic reaction: to the medication in the injection is rare and is usually a reaction to the preservative or x-ray contrast dye in the injection and not the steroid.
Nerve damage or spinal cord damage: Very rarely, the needle itself can cause injury to nerves; compression of nerves or the spinal cord from hematoma (pocket of blood) or pus (from infection) may result in damage. Obstruction of blood supply may also cause permanent nerve or spinal cord injury.
Arachnoiditis: A painful condition caused by the inflammation of the arachnoid membrane (the middle membrane of the three membranes covering the spinal cord) that may occur if medication is injected into the spinal fluid. Extremely rare.
Corticosteroids: Corticosteroids (or steroids) are similar to cortisol, which is produced naturally by your own body, but these synthetically produced steroids are more potent and longer lasting. Corticosteroids have powerful anti-inflammatory effects.
Local Side Effects of Corticosteroids in Spinal Injections: Too many steroid injections into the same area may weaken tendons and ligaments and cause thinning of joint cartilage.
Short-term side-effects from the steroids in a spinal injection: There may be bouts of facial flushing with a feeling of warmth the day after the injection. For several days after a spinal injection diabetics need to monitor their blood sugar carefully as blood sugar levels may be elevated.
Many of the side effects go away within a few months after discontinuing the steroids. Some side effects, such as stretch marks, osteoporosis and cataracts (cataracts are fortunately a rare side effect) do not go away on their own.