by Nicole Berardoni M.D., Paul Lynch M.D., and Tory McJunkin M.D.
Epidural steroid injections (ESIs) are a frequently-used treatment for chronic pain syndromes. A common characteristic among the syndromes treated with epidural steroid injections is a pain described as “radicular pain.”The word radicular means root and typically refers to an irritated nerve root (radiculitis) or weakness associated with an affected nerve root (radiculopathy).
Radicular pain is pain that radiates from the spine down an irritated spinal nerve root. Irritation of a spinal nerve in the low back, called lumbar radiculopathy, causes pain that typically travels down a leg. Cervical radiculopathy describes pain that travels down an arm. Epidural injections are also used to treat nerve compression in the neck (cervical spine), as well as the low back (lumbar spine).
Conditions commonly treated with ESI:
- Degenerative disc disease (Botwin 2007)
- Spinal stenosis
- Herniated discs (Lin 2006)
A study done at the Florida Spine Institute in 2007 confirmed that epidural steroid injections help reduce bilateral radicular pain and improve standing and walking in patients with degenerative lumbar spinal stenosis (Botwin 2007).
Procedure – Epidural Steroid Injection
The procedure involves injecting a medication into the epidural space, where irritated nerve roots are located. This injection includes both a long-lasting steroid and a local anesthetic (lidocaine, bupivacaine). The steroid reduces the inflammation and irritation, and the anesthetic works to interrupt the pain-spasm cycle and nociceptor (pain signal) transmission (Boswell 2007). The combination medicine then spreads to other levels and portions of the spine, reducing inflammation and irritation. The entire procedure usually takes less than 15 minutes.
The most important and greatest success achieved with the use of epidural steroid injections (ESI) is the rapid relief of symptoms that allows patients to experience enough relief to become active again. With this help, patients regain the ability to resume their normal daily activities.
There are several types of epidural steroid injections, and the specific type you receive depends on the cause of your pain syndrome. The trained pain specialist will decide which procedure is more beneficial to you after reviewing your history, performing a physical exam, and determining the cause of your pain. The main difference in the types of ESIs is the position where the needle is inserted as well as the amount of nerve roots treated.
Types of Epidural Steroid Injections
Intralaminar Injection: After your skin is anesthetized, the needle enters the mid-line of your back between your spinous processes (most prominent bones in the mid-line of your spine). The needle enters between the lamina of two vertebrae directly posterior to the vertebrae. The combination of steroid and anesthetic is delivered into the epidural space in the midline and spreads to the nerve roots on both sides of the spine. The evidence for interlaminar epidural steroid injections is strong for short-term relief and limited for long-term relief in managing radiculopathy.
Transforaminal Injection: After your skin is anesthetized, the needle enters through the side of the vertebra above the opening for the exiting nerve root. This approach treats one side at a time and is thought to be more specific. Pain specialists who are treating patients who have undergone previous spine surgery and have foreign bodies (surgical pins, surgical rods, or screws) as well as previous scarring prefer this method because they are able to avoid these structures. There is powerful evidence suggesting that transforaminal ESIs are effective for short-term and moderate for long-term improvement in managing lumbar back pain (Manchikanti 2007).
Caudal Injection: After your skin is anesthetized, a needle enters the epidural space by your tailbone. This technique allows for a catheter to be placed (Racz catheter) and larger volumes of steroid and anesthetic to be delivered. The additional medication can be used to affect more nerve roots distributing to the inflamed area at the same time. Often caudal ESIs are combined with another procedure called lysis of adhesions or the Racz Procedure, which is used to treat epidural scaring. The evidence for caudal ESIs is similar to that of the transformational ESIs.
Benefits of Epidural Steroid Injections
Epidural steroid injections are considered routine and relatively painless. Approximately 72% of patients experienced immediate pain relief in a 2007 research trial to evaluate the usefulness of a cervical interlaminar epidural steroid injection in patients with neck pain and cervical radiculopathy (Kwon 2007). If pain relief is only moderately achieved with the first injection, then another injection can be given in two weeks that may provide additional relief.
The use of multiple injections was studied by the Department of Anesthesiology and Intensive Care at the University of Pavia, Italy, and they concluded that therapy with multiple epidural steroid injections (ESIs) provide better control of chronic neck pain compared to that with a single injection (Pasqualucci 2007). Therefore likely your treating pain physician will recommend multiple ESIs. Often these procedures are done in sets of three.
The most important and greatest success achieved with the use of ESIs is the rapid relief of symptoms that allows patients to experience enough relief to become active again. With treatment, patients are often able to resume their normal daily activities.
Risks of Epidural Steroid Injection
Epidural steroid injections (ESIs) are considered an appropriate non-surgical treatment for many patients who suffer from back and neck pain. Although ESIs are considered safe and are one of the most commonly performed procedures in the world, there are risks associated with the procedure. The major risks associated with this procedure involve bleeding, infection, post-dural puncture headache, and nerve damage.
Another common complication of chronic pain is central sensitization. This is a development involving both the peripheral nervous system (PNS) and the central nervous system (CNS). Local tissue injury and inflammation activate the PNS, which sends signals through the spinal cord to the brain. Central sensitization occurs when there is an increase in the excitability of neurons within the CNS at the level of the spinal cord and higher. Eventually normal inputs from the PNS begin to produce abnormal responses. Low-threshold sensory fibers activated by very light touch of the skin activate neurons in the spinal cord that normally only respond to painful stimuli. As a result, an input that would normally produce a harmless sensation now produces significant pain.
The other risks of epidural steroid injections may be directly related to the medications injected. Some of the potential side effects of corticosteroids include elevated blood sugar, weight gain, arthritis, stomach ulcers, and transient decrease in immune system function. All patients before receiving an ESI should be assessed by their physician about risk assessment for the procedure.
Patients with an allergy to any anesthetic, are on blood thinning medications, have an active infection, or are pregnant should consult with their pain physician before receiving the procedure.
Outcomes of Epidural Steroid Injection
The amount and duration of pain relief vary from person to person and is dependent on many other factors, including underlying pathology and activity level. Some can have relief that lasts for years while others have short-term relief. It is important to discuss with your physician your response to epidural steroids in order to plan future treatment options.
The Department of Rehabilitation Medicine at the University of Washington conducted a study that compared the risks and efficacy between surgical alternatives versus lumbar epidural steroid injections (ESIs). In their conclusion, “when weighing the surgical alternatives and associated risk, cost, and outcomes, lumbar epidural steroid injections are a reasonable non-surgical option in select patients” (Young 2007).