Continuing Education Activity

Epidural steroid injections have been utilized for pain relief since 1952. When indicated, they are an invaluable non-surgical treatment for low-back pain radiating to the lower extremities and less commonly, for neck pain radiating to the arms. Performing an effective epidural steroid injection requires the steroids to reach the epidural space. Successful epidural steroid injections provide pain relief, allowing restoration of function and return to a physical therapy regimen, when indicated. This activity reviews the indications and technique involved in performing an effective epidural steroid injection and highlights the role of the interprofessional team in managing patients with low back pain.

Objectives:

• Identify the indications for epidural steroid injections.
• Describe the preparation required for epidural steroid injections.
• Explain the potential complications of epidural steroid injections.
• Explain how interprofessional team strategies can optimize care coordination and communication to advance the appropriate and safe use of epidural steroids for low back pain and improve outcomes.

Introduction

Chronic low back pain(LBP) and neck pain is the most common cause for years lived with disability in the world.[1][2][2][2] There are a variety of causes that can lead to LBP that include disc herniation, facet arthritis, discogenic pain, etc. Epidural steroid injections have been utilized for pain relief for such conditions since 1952. When indicated, epidural steroid injections are an invaluable non-surgical treatment for low-back pain radiating to the lower extremities and less commonly, neck pain radiating to the arms. The procedure involves the administration of steroids into the epidural space to treat the discogenic origin of the pain. If successful, epidural steroid injections will provide pain relief, allowing restoration of function and/or return to a physical therapy regimen.[3][4][5][6]

Anatomy and Physiology

The spinal cord and brain are covered by three protective layers known as meninges. The innermost layer is the pia mater, which articulates directly with the surface of the spinal cord. The middle layer is known as the arachnoid mater. Lastly, the dura mater is the outermost and thus toughest protective layer of the spinal cord. It is separated from the vertebrae by the epidural space. The epidural space contains the dural sac, blood vessels, fat, connective tissue, and spinal nerves. The contents of the dural sac include the spinal cord (ending at L1/L2) and the cauda equina. The spinal dura mater is critical to the peripheral nervous system as it creates pathways (via dural sheaths) by surrounding exiting nerve roots from the spinal cord.

The vertebral column also acts to protect the spinal cord. It consists of 33 bones (vertebrae), many of which are separated by an intervertebral disc. This includes seven cervical, twelve thoracic, five lumbar, five sacral (fused), and four coccygeal (fused) vertebrae. Spinal nerve roots exit the spinal column via two lateral openings, called intervertebral foramina, formed between two contiguous vertebrae.[7]

Indications

Epidural steroid injections treat pain caused by irritation and inflammation of spinal nerve roots. One specific type of pain, known as radicular pain, causes radiation along the dermatome of the affected spinal nerve. Many conditions may irritate the spinal nerve roots, which most commonly presents with low back (lumbar) pain with radiation down the buttocks or legs (e.g., sciatica). Also prevalent are patients with a neck (cervical) pain with radiation to the arms.[8][9][10]

The most common cause of spinal nerve root irritation is intervertebral disc pathology. In herniated discs, the center portion of the disc (nucleus pulposus) pushes through the outer layer (annulus fibrosis) placing pressure and ‘pinching’ the adjacent spinal nerve root. This pressure results in pain, weakness, and/or numbness in the distribution of the irritated nerve. Similarly, in degenerative disc disease, the breakdown of intervertebral discs over time may cause the collapse of intervertebral space resulting in compression of spinal nerve roots.

Another common indication for epidural steroid injection is nerve root irritation secondary to spinal stenosis. Spinal stenosis is a condition causing narrowing (stenosis) of the spinal canal or the canals of exiting nerve roots. Spinal stenosis is most commonly caused by arthritis of the vertebral joints (facets) or intervertebral disc pathology as discussed above.

 Other conditions in which epidural steroid injections may be indicated are:

• Non-specific radiculitis  
• Vertebral bone spurs impinging spinal nerve roots 
• Thickening of ligamentum flavum 
• Postlaminectomy syndrome 
• Facet or nerve root cyst with radicular pain 
• Post-herpetic or post-traumatic (including intercostal) neuralgia 
• Compression fracture with radicular pain 
• Spondylolysis 
• Spondylolisthesis 
• Scoliosis causing nerve root irritation    

One of the systematic reviews published evaluated 70 studies for lumbar epidural steroid injections, evidence for efficacy was good for lumbar disc herniations, fair for spinal stenosis, and poor for failed back surgery syndrome.[11] Another meta-analysis published showed good efficacy for use of epidural steroid injections for spinal stenosis and lumbar radiculopathy.[12] Kennedy et al. published the results of a prospective study showing the effectiveness of ESI in the treatment of lumbar radicular pain. Even though patients had good pain relief, but it was found that the pain relief was short-lived.[13] Another study conducted by Singh et al. showed that two-level transforaminal epidural steroid injections provide better pain relief compared to one-level TFESI.[14]

While the evidence of efficacy for Epidural steroid injections is strong, the longevity of pain relief is still not great and patients do need other forms of therapy for sustained pain relief.[15][16][1]

Contraindications

Absolute contraindications to epidural steroid injection include:

• Systemic infection or local infection at the site of injection
• Bleeding diathesis or full anticoagulation
• Significant allergic reaction/hypersensitivity to contrast, anesthetic, or corticosteroid
• Local malignancy
• Patient refusal

Relative contraindications to epidural steroid injections:

• Uncontrolled diabetes mellitus
• Congestive heart failure
• Pregnancy (due to fluoroscopy)

Equipment

Epidural steroid injections require:

• Fluoroscopic C-arm x-ray device 
• Epidural spinal needles
• Local anesthetic (lidocaine or bupivacaine)
• Steroids (methylprednisolone acetate, triamcinolone acetate, betamethasone acetate, and phosphate or dexamethasone phosphate)
• Loss of resistance syringe
• Contrast solution
• Sterile gloves and drapes
• Betadine

Epidural steroid injection may be completed with only topical local anesthesia or under intravenous (IV) sedation. In either case, it is necessary to have blood pressure cuffs, cardiac monitors, and pulse oximeters to monitor vital signs.

Personnel

Staff includes a physician trained in epidural steroid injections, nurse or assistant, a fluoroscopic C-arm operator, and an anesthesiologist to monitor patient vitals. All staff should be trained for the management of potential complications of the procedure.

Preparation

Risks and benefits of the procedure should be discussed with the patient and if in agreement, the patient must sign a written consent. Before the injection, a time-out is necessary to verify patient identity and injection site. The patient is to lie in a prone position on the fluoroscopy table, and once the location of injection is identified, the area should be marked, cleaned with betadine, and covered with sterile draping.

Technique or Treatment

Epidural steroid injections may be classified by location (cervical, thoracic, or lumbar) and by the path of the needle (interlaminar, transforaminal, or caudal). In this discussion, we will review the different techniques for interlaminar (between the lamina), transforaminal (across the foramen), and caudal (via the sacrum) epidural steroid injections.[17][18][19]

Interlaminar Epidural Steroid Injection (medial approach)

With the patient lying prepped and in a prone position, the interlaminar space between two contiguous vertebrae is identified via an anteroposterior (AP) view on fluoroscopic x-ray. Next, the skin and underlying tissue are injected with local anesthetic (e.g., lidocaine or bupivacaine). Using a midline or paramedian approach between the spinous processes, an epidural spinal needle is inserted into the intended injection site. From superficial to deep, the needle penetrates the skin, subcutaneous tissue, supraspinous ligament (median approach) or paraspinal muscles (paramedian approach), and the ligamentum flavum. A lateral view with the fluoroscopic x-ray is then obtained to confirm the position of the needle. The needle is then advanced using a loss of resistance syringe filled with 1ml of air or normal saline. As the needle passes the ligamentum flavum and enters the posterior epidural space, a sudden loss of resistance will occur allowing the syringe to inject a minimal amount of air or normal saline into epidural space due to the change in pressure. The loss of resistance syringe is then replaced with a syringe filled with the contrast solution, which is then injected to confirm placement of the needle in the epidural space. Once spread of contrast is confirmed in AP and lateral views, steroid (e.g., methylprednisolone, triamcinolone, betamethasone or dexamethasone) with or without local anesthetic is injected into epidural space. Finally, the needle is then withdrawn, and pressure is maintained at the injection site to prevent bleeding.

Transforaminal Epidural Steroid Injection (lateral approach)

With the patient lying prepped and in a prone position, the lateral foraminal space between two contiguous vertebrae is identified via an oblique view on fluoroscopic x-ray. This view displays the classic “Scottie dog,” an anatomical landmark used for needle guidance. Once proper injection site is identified, the skin and underlying tissue are injected with local anesthetic (e.g., lidocaine or bupivacaine). An epidural spinal needle is then inserted and directed under the pedicle of the superior vertebrae. A lateral view on x-ray is obtained to determine needle depth and to prevent damage to the nerve root. The needle is then advanced until it reaches the outer intervertebral foramen. Contrast injection confirms needle position in both lateral and AP views displaying epidural spread. Steroid (e.g., dexamethasone) with or without local anesthetic is then injected into the epidural space. Finally, the needle is withdrawn, and pressure is maintained at the injection site to prevent bleeding.

Caudal Epidural Steroid Injection

With the patient lying prepped and in a prone position, the sacral hiatus is identified via an AP view on fluoroscopic x-ray. Once proper injection site is identified, the skin and underlying tissue are injected with local anesthetic (e.g., lidocaine or bupivacaine). An epidural spinal needle is then inserted and directed through the sacral hiatus. A lateral view on x-ray is obtained to determine needle depth. Needle placement below the S2-3 intervertebral disc space will decrease the risk of dural puncture. Contrast injection confirms needle position in both lateral and AP views displaying epidural spread. The steroid is then injected into the epidural space. Finally, the needle is withdrawn, and pressure is maintained at the injection site to prevent bleeding.

Complications

Although rare, possible complications include:

• Bleeding 
• Infection      
• Allergic reaction 
• Nerve injury 
• Transient lower or upper extremity numbness and/or tingling 
• Dural puncture causing positional headache[20] 
• Epidural abscess 
• Epidural hematoma 
• Transient back or lower extremity pain
• Side effects of steroids (transient flushing/hot flashes, fluid retention, weight gain, elevated blood sugars, and mood swings)
• Adrenal suppression
• Paralysis (very rare)

Clinical Significance

When performed by a skilled physician, epidural steroid injections are a safe and integral treatment of back and leg or neck and arm pain caused by multiple conditions. It is imperative to note that epidural steroid injections are not necessarily designed to cure back or neck pain, instead, they are intended to provide temporary relief so that the patient may return to normal activities and/or continue their physical therapy regimen. Pain relief from epidural steroid injections may vary from one week to one year, and patients may require either a single or a series of injections for maximum relief.

Enhancing Healthcare Team Outcomes

While epidural steroid injections are widely performed. it is important to educate the patient that the response is not immediate, nor do these drugs provide pain relief in everyone.[21] Thus, the primary care provider, nurse practitioner and orthopedic nurse should educate the patient on lifestyle changes such as regular exercise, discontinuing smoking, maintaining a healthy weight and avoiding a sedentary lifestyle. 

The outcomes after epidural steroids are good but unpredictable. The injections do not usually cure the back pain but do help improve the quality of life for some time. [8][22]