What is an Epidural Steroid Injection?

Epidural steroid injections explained by Denver, Golden, Aurora, Boulder, Broomfield, Jefferson, and Littleton Colorado’s top pain doctors

First performed in 1885 by neurologist James Leonard Corning, the pioneer epidural injections employed cocaine as the anesthetic agent. However, the procedure was not used primarily as an analgesic until 1901. Patients receiving these early interventions were reported to have a form of radicular pain (i.e., pain that radiates outward from the spinal cord to the arms and legs) associated with intractable sciatica. By the 1930s, injections within the caudal region had received wide support as effective in providing relief from pain. The use of corticosteroids in these injections, however, did not emerge until 1953. Since that time, epidural steroid injections have been widely regarded as safe and effective, and are among the most commonly used interventional techniques employed to help patients achieve relief from pain and discomfort associated with a wide range of conditions. Further, epidural steroid injections continue to receive strong support for their role in treating radicular pain.

Prevalence rates estimate that approximately 90% of all adults will experience a pain condition at some point in their lifetime. Moreover, the Center for Disease Control (CDC) has suggested that chronic pain is associated with individual disability that is expected to have a detrimental impact on the individual’s functioning at work and at home. Chronic pain is regarded as a significant public health concern and has been implicated as the leading contributor to over $100 billion in annual costs as the result of productivity declines and medical expenses. Further, chronic pain is regarded as the most common reason cited for employment-related disability.

Indeed, the last ten years has seen a significant increase in studies exploring possible treatment methods. Further, randomized controlled trials have examined existing interventions for efficacy and effectiveness. Of the treatment options available for managing chronic pain, the most widely used method is epidural steroid injections. This interventional treatment option is minimally invasive and considered a safe and effective alternative to surgery for many pain conditions. Epidural steroid injections have received support from the United States Department of Health and Human Services, as well as the North American Spine Society as a critical treatment modality for helping patients achieve pain relief and return to their previous levels of activity. Back pain, in particular, has received the most empirical attention, though a large majority of the existing treatments for chronic pain in general have undergone thorough investigation prior to receiving empirical support.

Chronic pain conditions can vary widely. As such, it is recommended that you speak with your doctor to determine if epidural steroid injections are an appropriate treatment option for your pain condition. Indeed, many patients report significant reductions in pain almost immediately following the injection. Nonetheless, a small portion of individuals may require repeated injections in order to achieve the maximum relief from pain and discomfort.

Anatomy Of The Spine 

Typically referred to as the backbone or the spine, the vertebral column is located in the dorsal area of the torso. It is constructed of bones known as vertebrae. In the typical adult human, the vertebral column is comprised of 24 individual vertebrae and nine vertebrae that are fused together. Vertebrae are characterized by bone tissue that contains the centrum. Protruding from the centrum are several arches known as the vertebral arch.

Epidural Steroid InjectionThe spinal column is comprised of these vertebral bones, stacked on top of each other. The column itself can be divided into four separate regions: cervical curve, thoracic curve, lumbar curve, and sacral curve. The sacral curve is at the bottom of the spinal column and is comprised of four coccygeal vertebrae. The coccygeal vertebrae form the sacrum and the tailbone. Just above this is the lumbar curve, which consists of five vertebrae forming the lower back. The next section, above the lumbar curve, is the thoracic curve containing 12 individual vertebrae forming the middle and upper back. At the topmost region of the spinal column is the cervical curve, which forms the area of the neck.

Located within the spinal column is a long bundle of nerves known as the spinal cord. This nerve bundle is important for transmitting information to and from the brain. Beginning at the top of the spinal column, at the occipital bone, the spinal cord travels down within the spinal column through the first and second lumbar. The primary function of the spinal cord is the transmission of motor and sensory information, controlling motor movements, and controlling a number of reflexes. Crucial to human anatomy, the spinal cord is well-protected within the spinal column. It is surrounded by layers of membrane, referred to as meninges, as well as the vertebral bones of the spinal column.

The thick and durable membranes that surround both the brain and the spinal cord are referred to as the meninges, and include the pia mater, arachnoid mater, and the dura mater. Translated from Latin, dura mater means “tough mother.” This name is appropriate, as the primary responsibility of the dura mater is to protect the brain and spinal cord from possible injury. Tough and relatively inflexible, the dura mater also encases cerebrospinal fluid.

Falling just outside of the dura mater, around the outermost portion of the spinal canal is the epidural space. This area contains spinal nerve roots, lymphatics, fatty tissues, and blood vessels.

The point in which a nerve exits the central nervous system is referred to as the nerve root. Nerve roots can be classified into two groups: spinal nerve root and cranial nerve root. Should nerve roots become damaged or irritated, they can be a significant source of pain and discomfort. Damage sustained by nerve roots can also lead to paralysis (i.e., complete loss of motor function) or paresis (i.e., partial loss of motor movement or muscle weakness).

Conditions Related To Epidural Steroid Injections

Epidural steroid injections are recommended to treat a number of conditions. It is suggested that individuals consult with their physician for an evaluation of their individual symptoms of pain and to rule out any more serious conditions. During this initial evaluation, your physician will gather a detailed personal history, as well as in-depth information about your symptoms of pain and discomfort. This is essential for your physician to arrive at an appropriate diagnosis for your pain that will then inform your individual treatment plan. In terms of epidural steroid injections, this will also assist the physician in determining the specific location for the injection site. Indeed, there are a number of cases where the precise underlying cause for the patient’s pain is not known, thus your physician will ensure that more serious conditions are ruled out. For instance, in instances of low back pain, your physician will be sure that any specific spinal pathology or nerve root pain is ruled out prior to proceeding with epidural spinal injections. Physicians will also evaluate the patient’s risk for ongoing difficulties, which are also known as “yellow flags.” Identification of these factors prior to treatment will ensure that you receive the appropriate recommendations for follow-up care.

Back pain is an extremely common condition, with the large majority of adults experiencing symptoms at some point in their lifetime. Pain in the back or neck occurs from a variety of sources. Indeed, a large portion of instances of neck and back pain are the result of a specific pathology or degenerative process. Further, acute or chronic pain can emerge as the result of damage to the joints, ligaments, or muscle tissue that comprises the region surrounding the spinal cord.

Pain in the back or neck is generally described as pain or discomfort of the area that may even radiate outward toward the arms and legs. Nonetheless, there is marked variation in terms of the specific symptoms of pain. A portion of pain patients will report that their pain is sharp and stabbing; while another portion will describe that their pain is generalized or widespread and achy. Symptoms of pain often tend to fluctuate over time, with symptoms fluctuating through remissions and exacerbations of pain and discomfort. Many symptoms of pain will depend on the underlying cause for the discomfort.

Nonetheless, many common complaints with regard to pain conditions include:

  • Muscle spasms
  • Pain that radiates throughout the body
  • Cramping
  • Stiffness
  • Numbness, weakness, or tingling of the area
  • Sensory sensitivity to touch or pressure

Chronic pain patients, whose pain has not responded to traditional analgesic interventions, are excellent candidates for more interventional approaches, particularly epidural steroid injections.

Herniated DiscThe following is a list of conditions that are believed to benefit from epidural steroid injections:

  • Herniated disc: Found to occur more frequently among older individuals, disc herniated is associated with pain in the lower back. This condition is believed to be caused by damage to the intervertebral discs of the spinal column.
  • Osteoarthritis: Osteoarthritis is a condition that occurs as the result of years of wear and tear on the cartilage that protects the joints within the body, and is associated with significant pain.
  • Spondylolisthesis: Occasionally referred to as “nonspecific low back pain,” spondylolysis is a rare pain condition (prevalence rates estimated to be around 5%) caused by a degeneration of the spine. More specifically, vertebrae of the spinal column can dislocate and slip, which can lead to damage of the surrounding nerves.
  • Whiplash: Whiplash is a relatively common pain condition and is the result of a sudden jolt back and forth of the neck. Generally, this injury occurs during motor vehicle accidents or riding rollercoasters.
  • Spinal stenosis: Spinal stenosis is a relatively uncommon condition that arises from the narrowing of the spinal column. Individuals suffering from this condition generally report symptoms of pain and discomfort while walking.
  • Fractured vertebrae: Generally the result of a significant blunt force, fractured vertebrae can be the source of severe pain.
  • Spinal deformities: Spinal deformities are genetic deformities in the curvature of the spine and are generally quite rare (prevalence rates estimate them to be between 0.8% and 1.9%). These spinal abnormalities can be the source of chronic pain.
  • Spinal infection: Infections within the spine can be a significant source of back pain, in conjunction with high fever. Patients who are regular drug users are at increased risk for infection of the spine, as well as individuals who have undergone recent surgery.
  • Degenerative disc disease:Aging can lead to changes within the intervertebral discs of the spinal column. These changes can lead to tears that can cause significant degrees of chronic pain.
  • Lumbar radiculopathy: Also referred to as sciatica, lumbar radiculopathy, is the result of nerve compression by a herniated intervertebral disc. Individuals with this condition generally describe that their pain radiates down the leg.
  • Cervical radiculopathy: Pain that radiates down the arm can be caused by an intervertebral disc within the neck placing pressure on the surrounding nerves.
  • Failed back surgery: Back surgery can also lead to difficulties with regard to chronic pain. It is believed that scar tissue, which forms around the spinal nerves, is the primary source for pain with this condition.

Evidence in support of epidural steroid injections’ therapeutic effects on these conditions has been published by the American Society of Interventional Pain Physicians (ASIPP). Findings strongly suggest that epidural steroid injections are largely effective for managing both cervical and lumbar pain. Epidural steroid injections are also regarded as effective for use in diagnostics. When patients experience relief from pain following an injection into the epidural space, the diagnosis can be confirmed.

There is some literature to suggest that the successful use of epidural steroid injections can prevent unwarranted or premature surgery. One prospective, multisite study (SPORT; Spine Patient Outcomes Research Trial) compared two groups of disc herniation patients: one who had previously received epidural steroid injections and one who did not receive the injections. Results indicated that 56% of patients having received the epidural steroid injections opted against surgical intervention in contrast to 19% of the patients who had not received these injections.

How is an Epidural Steroid Injection Performed?

Epidural Steroid InjectionThe spinal cord is located inside the spinal canal and is surrounded by cerebrospinal fluid. This fluid acts as padding around the spinal cord, protecting the nerve bundle from damage. There is a thick and durable membrane, called the meninx (plural: meninges) that encases the spinal cord along with the cerebrospinal fluid. Just outside this protective membrane, between the meninges and the spinal column, is an area known as the epidural space. This is the area targeted when administering epidural steroid injections. Housing all of these structures is the spinal column (also known as the vertebral column), which is constructed of a number of individual bones stacked on top of one another known as vertebra. The spinal column in humans can be divided up into four different regions: cervical, thoracic, lumbar, and sacral. Thus, depending on the location of the patients reported pain, treatment can be focalized to one of these specified regions.

The procedure for epidural steroid injections is similar to most minor medical procedures. The patient’s skin in the area of the injection is thoroughly cleaned and prepped. Should the patient opt to be sedated during the procedure, it is essential that their blood pressure, heart rate, and respiration be monitored. The patient is placed on their stomach with their back facing toward the physician administering the injection. Generally, a topical anesthetic is applied to the surface of the skin.

In order to ensure that the needle has been inserted properly within the epidural space, a small X-ray (or fluoroscopic) device is used as a guide through the vertebrae. The physician may also test that the needle has been properly inserted by injecting a small amount of contrast dye before administering the steroid medication. The use of contrast dye can also assist the physician with ensuring that the proper distribution of the steroid solution will be achieved. The ideal distribution of steroids would include only those areas that have been inflicted with inflammation, so as to reduce the degree of exposure to the steroids. Typically, the entire epidural steroid injection procedure takes about fifteen minutes.

Three different needle placement options are available for patients who receive epidural steroid injections for the treatment of chronic pain. These include the following.

Interlaminar

The most common location where epidural steroid injections are administered is the interlaminar. During this procedure, the needle is placed in the area that lies between the two lamina of the middle back. Injection into this area ensures that the steroid will be administered to both the left and the right sides of the back. A large portion of the studies supporting the effectiveness of epidural steroid injections administered through the interlaminar site have focused on patients experiencing radicular pain as the result of disc herniation. A smaller portion of studies has supported the effectiveness of epidural steroid injections at the interlaminar site with patients complaining of spinal stenosis pain. Spinal stenosis is pain that does not originate from a herniated disc and frequently occurs as the result of a failed back surgery.

A major advantage of receiving an epidural steroid injection at the interlaminar site is that it is a more targeted administration of the medication than other injection sites, such as within the caudal region. This ensures that the steroids are more likely to permeate adjacent levels of the spine in order to provide relief from bilateral pain. Indeed, smaller amounts of medication are necessary for epidural steroid injections administered at the interlaminar site than those that are administered at the caudal site. Patients receiving an epidural steroid injection at the interlaminar site are at an increased risk for dural puncture.

Transforaminal

A second location where epidural steroid injections may be administered is in the area surrounding a specific nerve root. This procedure involves inserting a needle into the intervertebral foramen, which are two openings found along every pair of vertebrae that allow for the passage of nerve roots. Unlike the interlaminar method, a transforaminal epidural steroid injection treats only one side of the back. This approach is most commonly recommended for patients who have a history of back surgery, as it is a way to avoid bone grafts or the placement of pins and rods. The use of additional guidance in needle placement from a fluoroscope is essential with this procedure as it requires highly targeted needle placement.

While the transforaminal epidural steroid injection offers a more targeted approach to pain management, which is similar to that of steroid injections at the interlaminar site, the risk for dural puncture is particularly high among patients receiving the transforaminal injection. Existing studies, however, have provided some data to support the efficacy of transforaminal epidural steroid injections above that of the caudal and the interlaminar approaches among patients experiencing neuropathic spinal pain.

Caudal

A third location for epidural steroid injections is in the caudal region, in which the needle is inserted into the sacral canal. Given the size of the sacral canal, large amounts of the steroid may be injected within the epidural space. The most direct route available to the epidural space is through the sacral hiatus at the posterior wall of the sacral canal. Epidural steroid injections into the caudal region are accompanied by site-specific benefits, including a significantly reduced risk of dural puncture in comparison to both the interlaminal and the transforaminal approaches. This is likely because of the distance from the thecal sac, which is one of the protective membranes surrounding the spinal cord. As such, patients who are deemed most at risk for possible dural puncture are strongly encouraged to attempt an epidural steroid injection at the caudal site. Patients with other neurological complications are also strongly encouraged to attempt treatment at the caudal site.

The efficacy of epidural steroid injections at the caudal site has been supported by meta-analyses. Indeed, this procedure has been supported for both the long-term and short-term treatment of both back pain and leg pain that is the result of a disc herniation. Fewer studies are available to support the effectiveness of epidural steroid injections at the caudal site among patients complaining of discogenic pain, pain resulting from back surgery, and spinal stenosis.

Overview Of Methods

Evidence is mounting supporting the effectiveness of epidural steroid injections at all three injection site locations. Interestingly, a large portion of patients report significant decreases in their pain almost immediately following the injection procedure. Further, while a portion of patients will report gaining long-term relief from their pain following an epidural steroid injection, a small group will report recurrent pain despite a short period of being relatively pain-free. The underlying mechanism explaining why the patient’s pain returns is largely unknown. These patients may wish to return for additional epidural steroid injections. Currently, for this subgroup of patients, best practice recommends around one to two subsequent injections in order for the patient to achieve the full effect of the intervention. Typically, physicians will recommend a period of two weeks in between procedures. Further, your pain specialist will likely want to re-evaluate your pain symptoms prior to scheduling the follow-up injections.

At this time, there are no existing studies that specifically examine the optimal number of repeated injections for patients to experience full pain relief from epidural steroid injections. Indeed, controversy exists among physicians who specialize in pain management using interventional techniques. Specifically, a portion of existing studies suggest that there may not be any added pain relief benefit to repeated injections. Thus, it is recommended that physicians thoroughly evaluate their patient’s individual pain symptoms to develop an individualized treatment plan for managing their symptoms of chronic pain, as well as closely monitor and re-evaluate the patient’s condition as necessary.

It is recommended that individuals experiencing difficult symptoms of pain and discomfort speak with their doctor about the available options for managing their pain. Your physician will be able to provide you with a wealth of information and educational guidance in terms of making the right choice for pain management. For individuals whose pain is not severe and significantly impacting their ability to function on a day-to-day basis, the physician may strongly encourage you to return gradually to your previous level of activity and employ at-home treatments for pain management. Indeed, existing literature has found that up to 90% of patients reporting back and neck pain will experience a drastic improvement in the severity of their pain and discomfort simply by using conservative methods of treatment (e.g. physical therapy). Nonetheless, individuals with more severe and chronic pain, which has been unresponsive to typical pain relief treatments, are strongly encouraged to talk to their doctor right away.

Benefits Of Epidural Steroid Injections

Similar to most medical procedures, there are a number of factors known to predict whether a particular treatment will be effective or ineffective, and epidural steroid injections are no different. The effectiveness of epidural steroid injections and patient prognosis can be impacted by the training and expertise of the physician performing the procedure, the severity and duration of symptoms, or the root cause of the pain condition. Some studies have suggested that the strongest predictor to treatment response to epidural steroid injections is pain symptoms whose duration is less than three months.

Epidural steroid injections are not intended to treat the underlying cause of the patient’s pain. This procedure is meant to provide patients with relief from chronic pain while the body undergoes healing following injury. Epidural steroid injections are preferred by many, as they are relatively quick and painless. Moreover, epidural steroid injections can be performed on an outpatient basis, making them an ideal alternative to surgery for a number of pain conditions. Epidural steroid injections not only provide many chronic pain patients with significant reductions in pain, but they also can reduce the patient’s reliance on disability. Patients who have been forced to leave their job as a result of chronic pain may be able to gradually return to work following successful treatment.

Risks And Side Effects Of Epidural Steroid Injections

In general, epidural steroid injections are considered a safe and effective alternative to surgery for managing symptoms of chronic pain and discomfort. These procedures can be performed in an outpatient office and provide many patients with almost immediate reprieve from persistent and debilitating pain. Nonetheless, there is some risks with epidural steroid injections as with any medical procedure; however, studies have shown that the risk for complication following epidural steroid injections is very low.

Side effects following these procedures may include:

  • Steroid flush (i.e. a period of several days or more of flushing in the face and chest, accompanied by an overall feeling of warmth and temperature increase)
  • A period of several days or more of a temporary increase in symptoms of pain or discomfort
  • Headaches
  • Sleep disturbance (i.e. difficulty falling asleep, staying asleep, or complaints of restless or unsatisfying sleep)
  • Anxiety
  • Disturbance in mood or mood swings
  • Elevations in blood sugar
  • Nausea
  • Diarrhea
  • Bleeding at the injection site
  • Retention of water
  • Hot flashes

In rare instances, patients may report a numbing sensation in the affected arm or leg. This symptom tends to disappear within approximately eight hours. More serious complications in relation to epidural steroid injections are rare, and include bleeding, nerve damage, severe allergic reaction, infection at the injection site, and paralysis. In a very small number of cases, epidural steroid injections have been implicated as a contributing factor to the development of meningitis.

Research into the risks involved in epidural steroid injections has revealed a number of factors that place an individual at increased risk for complications following this procedure. For instance, it is known that individuals with poorly managed diabetes, uncontrolled blood pressure, bleeding disorders, prescriptions for blood thinners, known allergies to steroids, unstable angina or history of congestive heart failure, or suspected or known active infections are at significant risk for severe complications. It is recommended that these patients discuss alternative treatments for managing their chronic pain symptoms.

The long-term benefits of epidural steroid injections have not been well-studied. While many patients report long-standing relief from their symptoms of pain and discomfort following epidural steroid injections, others will experience recurrent pain despite multiple repeated injections. Nonetheless, these injections are considered a safe alternative to surgery for the treatment of chronic pain and discomfort associated with a number of conditions.

Mechanisms Of Action

The underlying mechanisms of action of epidural steroid injections have been the subject of debate among researchers and physicians. Indeed, many argue that the analgesic effects of epidural steroid injections are likely not the result of corticosteroids, which is in contrast to the general understanding of corticosteroids action within the body. More specifically, it is believed that epidural steroid injections are effective in reducing pain given that corticosteroids have an inhibitory effect on the enzymes that lead to inflammation, which is believed to be the source of pain in a number of pain conditions. Other properties of steroids may also play a role in their analgesic effects. For instance, steroids inhibit ion conduction and act to stabilize nerve membranes. Both of these processes are believed to contribute to the subjective experience of pain and discomfort.

Those who argue that steroids do not play a significant role in pain reduction have suggested that the injection itself may provide analgesic effects. Receiving an injection increases blood flow to the surrounding nerves that may act to slow or suppress the nerves ability to transmit pain information to the brain. Solutions that are administered in addition to the steroids may also provide some pain-relieving benefit, as they may act to cleanse nearby damaged nerves of damaging chemicals.

The precise mechanism of action remains a topic of controversy. Indeed, it is likely that a combination of the above factors best accounts for the effectiveness of epidural steroid injections. Nonetheless, more work is needed in the area.

Factors Related To Poor Outcome

Several factors have been identified as associated with an increased risk for a poor outcome following the use of epidural steroid injections for pain management.

Individuals at an increased risk for complications include those who:

  • Smoke
  • Have low job satisfaction
  • Are less educated
  • Have other co-existing pain complaints
  • Tend to experience psychological distress in the form of somatic complaints
  • Have fewer coping skills for stress
  • Also use opioids
  • Have had previously failed treatments
  • Report constant pain that does not increase with activity
  • Have a comorbid anxiety or mood disorder

These complications can occur in the form of a reduced effectiveness from the injection or an increased risk for the pain to return. Additionally, studies have identified that the ways in which individuals tend to cope with the stress associated with pain can influence their risk for complications. For instance, individuals who tend to catastrophize, report high baseline pain scores, tend to use avoidance as a coping strategy for feared situations, or possess more negative or pessimistic beliefs are at risk for a poorer outcome following epidural steroid injections.

Conclusion

A number of interventions are available to treat chronic pain. One of the most widely used interventional methods is the epidural steroid injection. This procedure provides relief for pain associated with a wide variety of pain conditions, particularly those arising from neuropathy of the spinal nerves. In general, epidural steroid injections are regarded as a safe and effective alternative to surgery for relieving pain. The procedure can be done on an outpatient basis and the injections themselves are relatively painless. The procedure takes approximately fifteen minutes. Many patients receiving epidural steroid injections have reported experiencing significant reductions in their pain and discomfort almost immediately following the procedure. Further, given that the procedure is non-surgical, patients may return to their daily activities almost immediately and without requiring a significant amount of recovery time. Side effects from this procedure are minimal and generally associated with the steroid medication.

The effectiveness of epidural steroid injections in terms of cervical and lumbar pain has been well-documented. Further, this procedure is also regarded as effective for treating radicular pain. The mechanisms of action underlying epidural steroid injections are believed to be associated with the anti-inflammatory action of corticosteroids; however, the literature is still somewhat unclear. Increases in blood flow as the result of the injection, as well as the cleansing quality of the saline solution have also received some support as underlying the effectiveness of epidural steroid injections.

Individuals who are interested in exploring whether epidural steroid injections will provide them with pain relief are encouraged to speak with their doctor. Your doctor will gather a detailed description of your symptoms and rule out any more serious conditions. This initial consultation will also provide information in order to develop an individualized treatment plan. In particular, patients whose pain has been unresponsive to previously attempted interventions may be excellent candidates for epidural steroid injections. Many individuals report relief from their pain and discomfort almost immediately following the epidural steroid injection procedure. While some patients do not experience complete relief from pain following a single procedure, epidural steroid injections may be administered through multiple injections. More research is needed in order to clearly identify the ideal number of injections to provide maximum relief from pain.

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