An epidural injection is a technique using a needle to inject a local anesthetic, with or without corticosteroids, into the epidural space around the spinal cord and spinal nerves. It is often done under x-ray guidance and may be performed in a physicians’s office or in a surgical setting.
Epidural injections are used in managing spinal pain secondary to discogenic pain, disc herniation, spinal stenosis, postsurgery syndrome and other conditions. In general, epidural injections are directed at the treatment of symptoms and not solely based on MRI findings. A 2011 study showed that MRI findings do not necessarily predict success of ESIs.
Spinal Epidural Injections or Select Nerve Root Blocks (Transforaminal) are types of interventional pain management procedures. Epidural injections of corticosteroids can be used for short-term pain relief associated with acute back pain or exacerbation of chronic back pain when injected close to the target area with the goal of pain reduction. Epidural injections should be used in combination with other conservative treatment modalities and not as stand alone treatment for long-term back pain relief.
Effectiveness of Epidural Injections
Epidural injections are one of the most commonly performed non-surgical treatments for low back pain (LBP). However, their extent of effectiveness in managing low back pain and lower extremity pain has been controversial. Interventional pain management specialists do not agree on how to diagnose and manage spinal pain and there is a lack of consensus with regards to the type and frequency of spinal interventional techniques for treatment of spinal pain.
Several studies and systematic reviews have been conducted recently to assess the benefits of epidural injections and it appears there is now high quality evidence to support the likelihood of benefit for multiple LBP conditions, including lumbar discogenic pain and lumbar radicular pain associated with disc herniation.
Indications for Epidural Injections or Selective Nerve Blocks (caudal, interlaminar, and transforaminal) (Injection of local anesthetics with corticosteroids):
(1) Acute pain or exacerbation of chronic back or neck pain with the following clinical timeframes:
– Neck or Back Pain with acute radicular pain:
1. after 2 weeks or more of acute radicular pain that has failed to respond or poorly responded to conservative management; OR
– Failed back surgery syndrome or Epidural fibrosis
1. typically not done immediately post-surgery: no sooner than 6 months post surgery
2. patient must engage in some form of other conservative treatment for a minimum of 6 weeks prior to epidural injections; OR
– Spinal stenosis or chronic neck or low back pain
1. patient must engage in some form of other conservative treatment for a minimum of 6 weeks prior to epidural injections
(2) Average pain levels of ≥ 6 on a scale of 0 to 10 or Intermittent or continuous pain causing functional disability.
Recommended Frequency of Repeat Therapeutic Injections:
(1) Epidural injections may be repeated only as medically necessary and the following criteria must be met for repeat injections:
– The prior injection had a positive response by significantly decreasing the patient’s pain (at least 30-50% reduction in pain after initial injections with significant functional improvement); AND
– The patient continues to have ongoing pain or functional disability (≥ 6 on a scale of 0 to 10); AND
– The patient is actively engaged in other forms of conservative non-operative treatment (unless pain prevents the patient from participating in conservative therapy); AND
– Injections meet the following criteria:
(A) There must be at least 14 days between injections;
(B) No more than 3 procedures in a 12-week period of time per region;
(C) Limited to a maximum total of 6 procedures per region per 12 months.
– Course of treatment, up to three epidural injections, regardless of approach must provide at least:
At least 50% or more cumulative pain relief obtained for a minimum of 6 weeks to be considered a positive and effective response.
– If the neural blockade is applied for different regions (cervical and thoracic regions are considered as one region and lumbar and sacral are considered as one region), injections may be administered at intervals of no sooner than 14 days for most types of procedures.
Relative Contraindications to Epidural Steroid Injectionss
- Poorly controlled diabetes—steroids increase glucose levels
- Poorly controlled glaucoma
- Severe spinal stenosis
- For diagnosis or treatment of facet pain
- Local infection at site of injection
- Diffuse infection
- Epidural lipomatosis: steroids may increase the lipomatosis
- Use of Anticoagulants: increased risk of hematomas and bleeding
- Osteopenia and osteoporosis
- Risk for avascular necrosis
- Risk for adverse effects with suppression of the hypothalamic–pituitary–adrenocortical axis scheduled for major surgery
- Those with poor wound healing and immunosuppression.
Three Routes of Administration of Epidural Injections
These procedures should be performed using fluoroscopic guidance. There are three routes of administration of epidural injections including transforaminal, interlaminar, and caudal approaches:
Interlaminar Epidural Injections
Interlaminar epidural injections access the epidural space between two vertebrae (Interlaminar) and are used with steroids to treat cervical, lumbar or thoracic pain with radicular pain. Interlaminar epidural injections are the most common type of epidural injection.
Transforaminal Epidural Injections
Transforaminal epidural injections (also called selective nerve root blocks) access the epidural space via the intervertebral foramen (nerve windows) where the spinal nerves exit from thecervical, lumbar or thoracic regions. They are used both diagnostically and therapeutically. Some studies report lack of evidence and risks of transforaminal epidural injections.
Caudal Epidural Injections
Caudal epidural injections access the epidural space through the sacral hiatus to treat the lower nerve roots of the spine. They are used with steroids to treat back and lower extremity pain. The most common reason for using the caudal approach is for Failed Back Surgery Syndrome.
Several systematic reviews that compared the efficacy of these three approaches provided conflicting results, although a 2015 review article supported the efficacy of epidural injections of local anesthetic with or without steroids administered with all three approaches: caudally, interlaminar, and with a lumbar transforaminal approach.
Epidural injections: Anesthetics Alone or with Steroids
Epidural injections may be given with anesthetics alone or with steroids (cortisone-like drugs including methylprednisolone, hydrocortisone, triamcinolone, betamethasone, and dexamethasone). There is currently a lack of evidence to support that local anesthetic with steroids is superior to local anesthetic alone in the use of ESIs for treating chronic low back with the exception of treating lumbar disc herniation associated with lower extremity radicular pain where the inclusion of steroids provided added benefit.
Mechanisms of Action
The findings of a 2015 systematic review, showing the equal effectiveness of local anesthetics alone and local anesthetics with steroid administered into the epidural space, facet joints, or over facet joint nerves, contrasts a long-held belief in the medical community emphasizing the effectiveness of steroids in treating spinal pain based on the theory of spinal pain having an inflammatory component. At least in the short-term, most of the benefit of epidural injections may derive from the solution itself, rather than the steroid. It may be explained by various mechanisms of steroids and local anesthetics, including the suppression of ectopic discharges from inflamed nerves, enhancing blood flow to ischemic nerve roots, the lysing of post-operative and inflammatory adhesions, a washout of proinflammatory cytokines, and reversal of peripheral and central sensitization. It has been theorized that the steroids may hasten the healing of annulus tears.
Safety of Epidural Injections
Patients at higher risk for complications from the use of steroids.
Since it appears that using epidural injections with local anesthetic alone may be a viable option, this choice may reduce the risk of complications from steroids. Patients at higher risk for complications from the use of steroids may benefit from ESIs with anesthetic alone. Higher risk patients include not only postsurgery patients, but also patients with diabetes at risk of hyperglycemia, plus those at a high risk of osteopenia and osteoporosis, those at risk for avascular necrosis, those with a risk for adverse effects with suppression of the hypothalamic–pituitary–adrenocortical axis scheduled for major surgery and those with poor wound healing and immunosuppression.
Complications of Epidural Injections
Even though the complications of fluoroscopically directed epidural injections are fewer than blind epidural injections, and have better effectiveness, multiple complications have been reported in scattered case reports, with only minor complications in randomized or non-randomized studies and systematic reviews.
Potential complications of epidural injections include multiple side effects, adverse events, and complications that range from minor soreness to major complications such as paralysis and death. These adverse effects include: the failure of targeted delivery of injectate; increased levels of pain and soreness; facial flushing and vasovagal reactions; intravascular penetration of the needle with bruising, local or profuse bleeding, local or epidural hematoma, spinal cord hematoma; dural or subdural puncture with subarachnoid or subdural blockade; postlumbar puncture headache, meningismus, pneumocephalus, infectious complications including epidural abscess, discitis, and meningitis; neurological trauma with thromboembolic phenomenon, nerve root trauma, spinal cord injection, spinal cord trauma, stroke; cauda equina syndrome; and adrenocortical suppression.
Many of these complications are predominantly found in cervical and thoracic transforaminal epidural injections that are now performed with decreasing frequency.
Mixed Safety Studies of Cervical and Lumbar ESIs
Published results of 4,265 injections on 1,857 patients over 7 years with 161 cervical interlaminar injections, 123 lumbar interlaminar injections, 17 caudal injections and 3,964 lumbar transforaminal injections (no thoracic epidural injections) identified a lack of major complications and reported 103 minor complications, for an overall complication per injection rate of 2.4%. In a review of complications of transforaminal lumbar epidural steroid injections, a study published the results of a total of 562 patients performed 1,305 times, with an overall incidence of vascular penetration encountered in 7.4%, an overall rate of minor complications of 11.5%, and no major complications.
In 2014, the Food and Drug Administration (FDA) issued a warning about the risk of serious, though rare, but potentially fatal, complications such as meningitis and rare, but real, catastrophic consequences, such as paralysis and death as well as the lack of effectiveness of epidurally administered steroid injections. However, this advice was issued based on cervical transforaminal epidural particulate steroid injections that resulted in catastrophic complications related to an improperly manufactured batch of injectble steroid solutions. Only 3% of total epidural injections involve cervical and thoracic transforaminal epidural injections.
Safety Studies of Lumbar ESIs
In a review of the complications of lumbar interlaminar and transforaminal epidural injections, it was reported that complications from lumbar epidural injections are extremely rare. In a review of complications of transforaminal lumbar epidural steroid injections, Karaman et al published the results of a total of 562 patients performed 1,305 times, with an overall incidence of vascular penetration encountered in 7.4%, an overall rate of minor complications of 11.5%, and no major complications. McGrath et al, in an evaluation of 3,964 lumbar transforaminal epidural injections, reported only minor complications in a small proportion of patients including flushing, chest pain, headache, weakness, itching, leg cramps, fever, etc.
LBP: Disc Pain Tx – Epidural Injections
- Epidural injection with or without steroid in managing chronic low back and lower extremity pain – a meta-analysis – 2015
- Comparison of the efficacy of saline, local anesthetics, and steroids in epidural and facet joint injections for the management of spinal pain: A systematic review of randomized controlled trials – 2015
- A Prospective Evaluation of Complications of 10,000 Fluoroscopically Directed Epidural Injections
- 2016 NIA clinical guidelines
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