What is Epidural Steroids?
Epidural steroid injections (ESI) have been useful in treating pain caused by lower spine disc injuries since the 1950s. They’re often used to treat radicular pain—a type of nerve pain—felt along the areas of the skin served by specific spinal nerves. This pain is commonly due to irritation of the nerve root, a result of a compressed or herniated disc and resulting inflammation in the spine. Other causes of this spinal nerve compression include conditions like spondylosis, spondylolisthesis, and overgrowth of the ligamentum flavum causing a narrowing of the nerve openings. In people with lumbosacral radiculopathy (nerve pain in the lower back and legs), over half of them experience disruption in their daily routine, and a quarter of them continue to suffer from severe pain unresponsive to standard medication.
About 14% of patients with lumbosacral radiculopathy may eventually need surgery for severe pain, sometimes accompanied by neurological problems. However, many people with spinal disk-related nerve pain show improvement with medication and rehabilitative treatment. Steroid injections into the epidural space (the area around the spinal nerves) are used to decrease inflammation and relieve pain, reducing the need for additional medications or surgery.
Steroids can be delivered to the epidural space from three directions: directly through the affected spinal nerve openings (transforaminal), between the protective coverings of the spinal cord (interlaminar), or into the lower portion of the spinal canal (caudal). This is commonly achieved using image guidance—fluoroscopy or less often CT scans—to properly place the needle and confirm the drug distribution. Epidural steroid injections have been extensively studied for their effectiveness in treating lower back and leg nerve pain, with current evidence strongly recommending their use for pain reduction up to 3 months after the injections. However, the research doesn’t consistently show an improvement in physical disability or a reduction in the need for surgery.
Steroid injections in the neck area (cervical ESIs) have also been effective in providing temporary relief for nerve pain caused by herniated discs or pain originating in the discs themselves. However, the long-term effects are not well-studied. The research primarily focuses on interlaminar cervical ESI, with less emphasis on steroid injections directly through nerve openings. Although rare, serious side effects can occur with epidural steroid injections.
What Causes Epidural Steroids?
There are several typical reasons why the root of a nerve might be squeezed and need to be treated with epidural steroid injections (ESIs). These can include a slipped disc between the bones in your spine (an intervertebral herniated disc), wear and tear on your spine (spondylosis), a condition where a bone in your spine slips out of place (spondylolisthesis), and thickened ligaments in your spine (ligamentum flavum hypertrophy). Any of these issues can narrow the space where nerves pass through your spine (known as neuroforaminal stenosis).
Risk Factors and Frequency for Epidural Steroids
Cervical pain, or neck pain, is the fourth main reason people in the United States have disabilities. Each year, for every 1000 adults, one will experience cervical radiculopathy – a condition where a nerve in the neck becomes irritated or pinched. In recent years, the use of injections to treat neck and upper back pain (cervicothoracic ESIs) has dramatically increased, with rates varying from 5 to 40 out of every 1000 people who receive Medicare.
Low back pain is the fifth main reason people seek medical help in the U.S, costing between 100 million to 50 billion dollars. About 40% of patients with low back pain also experience lumbosacral radicular pain, which is a type of pain that moves from the lower back down below the knee. The annual rate of people with lower back pain that is felt below the knee ranges from 9.9% to 25%.
- Cervical pain is a top cause of disability in the U.S.
- Each year, one in every 1000 adults experiences cervical radiculopathy.
- The use of cervicothoracic ESIs, injections for neck and upper back pain, has been on the rise.
- Low back pain makes the top five reasons for seeking medical help in the U.S.
- Low back pain costs as much as 100 million to 50 billion dollars per year.
- About 40% of people with low back pain also experience pain that moves from the lower back down below the knee.
- Annually, 9.9% to 25% of people experience lower back pain that is felt below the knee.
Treatment Options for Epidural Steroids
The “safe triangle” is a term used in medical procedures to describe the target area for transforaminal injections – injections that are administered near the spine to help with pain relief in certain conditions. This area is called the “safe triangle” because it is formed by certain structures in your body, the inferior margin of the pedicle, a line from the anterior margin of the pedicle, and the exiting nerve. Doctors use this triangle as a guide to minimize risk while giving these injections.
Even though it’s called the “safe triangle,” this method isn’t without risks. It can potentially cause nerve injury, puncture the intrathecal space (a space that involves your spinal cord), or cause vascular injection (injecting medication into a blood vessel). Recent studies have also highlighted some dangers involved with this method. These risks factor in with the presence of blood vessels supplying the spine (radiculomedullary arteries) and reported cases of paraplegia (paralysis of the legs and lower body).
Despite these concerns, healthcare providers employ different strategies alongside the “safe triangle” technique to improve the safety and effectiveness of these injections. One such strategy is the posterolateral approach. In this method, doctors insert the needle into the back part of a bony channel called the neural foramen, instead of the front part – this is instead of using the standard safe triangle guide. This approach can be helpful if the patient has a narrowing of the foramen (foraminal stenosis) or experiences nerve pain during the procedure.
A variation of the “safe triangle” approach is the Kambin triangle method. This method targets the lower part of the neural foramen at the level where your backbones meet and form a joint (the intervertebral disc). By avoiding needle insertion too far forward during this procedure, medical professionals can minimize the chance of injecting into the disc or causing a puncture within the lining that surrounds the spinal cord. Studies have found that the Kambin approach may reduce the risk of injecting into a blood vessel compared to the safe triangle method, but it does increase the risk of injecting into the disc.
For patients with severe neuroforaminal stenosis or who need injections in the neck region, doctors might opt for the interlaminar approach instead. This method can help avoid the risk of injecting into a blood vessel and severe outcomes from it. The procedure involves placing the patient face-down, and after providing local anesthesia, a needle is introduced to target the back part of the backbone in the spinal segment. Medical professionals insert the needle a small distance at a time until a change in resistance signals entrance into the epidural space – this is the space outside the protective membrane covering the spinal cord and nerves. Any discomfort or unusual sensations felt by the patient can indicate that the needle is not correctly positioned.
While the interlaminar approach has its advantages, it’s critical to advance the needle cautiously to avoid damaging the protective membrane of the spinal cord or the cord itself. There’s also the risk of complications like an epidural hematoma (a clot in the epidural space) or an abscess (a swollen area within body tissue), which could compress the spinal cord. Therefore, if possible, sedation is typically avoided, allowing the patient to alert the doctor if they feel any pain or strange sensations during the procedure.
What else can Epidural Steroids be?
There are several health conditions which are correlated with the lumbar region – the lower part of the spine. These include:
- Lumbar compression fracture, which is a break in one of the vertebra in the lower back
- Lumbar degenerative disk disease, where the cushioning discs in the lower spine wear down over time
- Lumbar facet arthropathy, a condition that affects the joints in the back of the spine
- Lumbar spondylolysis and spondylolisthesis, types of stress fractures that can lead to spine misalignment
- Mechanical low back pain, a broad term for pain caused by an issue with the mechanics of the back itself
- Physical therapy and rehabilitation for myofascial pain, which is pain that affects the connective tissues of the muscles
- Rehabilitation for osteoarthritis, which is a condition that breaks down the cartilage in your joints, including those in the lower back
- Rheumatoid arthritis, a chronic inflammatory disorder that can affect the joints in the lower back
- Spondylolisthesis imaging, a diagnostic imaging technique that can help identify and assess the condition of spondylolisthesis
What to expect with Epidural Steroids
Epidural Steroid Injections (ESIs) primarily help treat neck or lower back nerve pain and in some cases, might prevent the need for surgery. However, past research into the effectiveness of these injections has some limitations, like varying study methods and wide-ranging criteria for patient inclusion. Different types of ESIs, such as those injected in between the vertebrae (transforaminal), into the space between two vertebrae (interlaminar), or at the base of the spine (caudal), are often included in these studies. Other than nerve pain, ESIs also treat a range of other conditions like general back pain, failed back surgery syndrome, and narrowing of the spinal canal.
Recently, a few reviews and meta-analyses have shown that transforaminal and interlaminar ESIs can offer consistent pain relief for people with lower back pain correlated with nerve pain symptoms. However, the same can’t be said for general back pain. In some instances, ESIs can provide relief for as long as 12 months and even prevent surgery. For nerve pain caused by a herniated disc, there’s good evidence that using corticosteroid drugs along with local anesthetics is an effective method. The benefit of transforaminal injections is that they can get the medication closer to the spinal nerve, the anterior epidural space, and the dorsal root ganglion. However, when comparing the interlaminar method with the transforaminal, they’ve both shown similar results after 6 months although transforaminal does show an early benefit at 2 weeks. Other studies have shown that interlaminar ESIs aren’t significantly effective for general back pain except for perhaps short-term relief. Also, the dosage of steroids doesn’t seem to affect the level of pain relief in chronic back pain or lower back nerve pain.
In terms of ESIs for neck pain, the research studies have varied methods and results, similar to lower back ESIs. There’s a stronger body of evidence supporting interlaminar ESIs over transforaminal ESIs for neck pain. It shows durability in pain relief and improvements in disability measurements at 12 to 24 months. However, multiple injections were often needed. It is also indicated for neck-related nerve pain, disc herniation, neck-specific spinal stenosis (narrowing of the spine), and chronic pain following neck surgery.
Possible Complications When Diagnosed with Epidural Steroids
Serious side effects linked to Epidural Steroid Injections (ESI) that require hospital care, like spinal infections, buildup of blood outside blood vessels (hematoma), and severe body-wide infections (sepsis), are extremely rare – they were found in less than half a percent of cases in a large research study in Europe. Even though instances of permanent nerve damage from ESIs are also rare, doctors take measures to prevent the needle from reaching important blood vessels and nerves during the procedure. This includes checking for entry into an artery before injection, watching for the flow of the injected contrast agent, performing an angiography, and administrating a test dose of anesthetic.
A type of ESI involving particle-based steroids can occasionally lead to persistent nerve damage. This can occur if the injection accidentally enters a small artery feeding the spinal cord, blocking it and causing damage to the spinal cord. It can also occur if the injection enters arteries linked to the back part of the brain, leading to a stroke. Ultrasound studies have shown that the chance of hitting nearby blood vessels ranges between 5.5% and 13.5% when targeting selective nerve roots from C5 to C7.
An American Pain Society survey reported that out of 1340 doctors, 287 reported 78 complications from cervical ESIs, including 16 brain strokes, 12 spinal cord strokes, 2 simultaneous brain and spinal cord strokes, and 13 resulting in death. The medical literature also reports at least 18 cases of paralysis following lumbar ESIs, despite the usage of techniques to visualize the process.
There are varying techniques to safely apply the medicine while avoiding nerves and blood vessels. However, there is no consensus on the safest method to decrease the possibility of nerve injury. A review of 18 paralysis cases following lumbar ESIs illustrated that in a majority of cases, the needle was positioned in the upper part of the neural opening. Confirmation of needle placement is obtained through injecting a contrast agent which produces an image. If the needle tip is not far enough within the opening, the injected fluid may not travel freely. In this case, only the nerve is highlighted, and this is referred to as a selective nerve block.
Here’s a list of potential ESI complications:
- Spine infection
- Hematoma
- Sepsis
- Permanent neurological complications
- Nerve damage from particle-based steroids
- Cervical spinal cord stroke
- Vertebrobasilar brain stroke
- Paralysis following lumbar ESI
Preventing Epidural Steroids
You can safely receive epidural steroid injections, which are used to reduce pain, 3-4 times a year. It’s important to leave at least two weeks in between each injection. Usually, it might take two to three injections to effectively ease the pain. If these injections don’t seem to be helping much, it’s a good idea to talk to your doctor about other possible treatments.
After getting an injection, you might notice some side effects. These can include discomfort where the injection was given, feeling irritable, having trouble sleeping, higher than normal blood sugar levels, swelling in the legs, hot flashes with a red face and chest, or a change in skin color where the injection was given.
If you get a very high fever, feel severely nauseous or vomit, can’t control your bowel or bladder, or start to feel numb, tingly, or weak, it’s important to seek medical help as soon as possible.
