Epidural steroid injections (ESI) utilized to treat back pain with sciatica.
ESI is the most frequently performed procedure in pain clinics.
More than 500,000 epidural glucocorticoid injections are administered in US Medicare population alone annually.
Approximately 4800 epidural injections per 100,000 Medicare patients were performed in 2011 for a total of 2.3 million procedures.
Epidural steroid injections (ESIs) have been recognized as an integral part of nonsurgical management of radicular pain from lumbar spine disorders.
ESIs can provide diagnostic and therapeutic benefits.
May help to identify the epidural space as the potential pain generator, through pain relief after local anesthetic injection to the site of presumed anatomic pathology.
If the patient receives weeks or more of pain relief, then it may be reasonable to assume that an element of inflammation was involved in his or her pathophysiology.
Chronic inflammation can result in edema, wallerian degeneration, and fibrotic changes to the neural tissues.
Radicular pain often is the result of nerve root inflammation with or without mechanical irritation.
Mechanical compression alone to the nerves causes only motor deficits and altered sensation but does not necessarily cause pain.
Inflammation within the epidural space and nerve roots, as can be provoked by a herniated disk, is a significant factor in causing radicular pain.
High level of phospholipase A2 (PLA2), an enzyme that helps to initiate the inflammatory cascade, has been demonstrated in herniated disk material from surgical samples in humans.
Leukotriene B4, thromboxane B2, and inflammatory products also have been discovered within herniated human disks after surgery.
The radicular pain due to lumbar spinal stenosis is probably related to the inhibition of normal nerve root vascular flow with resultant nerve root nutrition, nerve root edema, and nerve root dysfunction.
Nerve root compression can cause axon ischemia, impair venous return, promote plasma protein extravasation, and cause local inflammation.
Similar mechanisms of radicular pain occur in the thoracic and cervical spine.
It is suggested radicular pain is the result of inflammation of the nerve root in the epidural space provoked by leakage of disk material, compression of the nerve root vasculature, and/or irritation of dorsal root ganglia from spinal stenosis.
Analgesic effects of corticosteroids most likely are related to the following mechanisms:
Inhibition of PLA2 and inflammation
Inhibition of neural transmission in nociceptive C fibers
Reduction of capillary permeability
The primary indication for epidural steroid injection (ESI) is radicular pain associated with a herniated nucleus pulposus
Lumbar, thoracic, and cervical epidural steroids may be indicated for lumbar radicular pain associated with any of the following conditions:
Lumbosacral disk herniation
Spinal stenosis with radicular pain.
Compression fracture of the lumbar spine with radicular pain.
Facet or nerve root cyst with radicular pain.
Absolute contraindications for ESIs include:
Systemic infection or local infection at the site of a planned injection.
Bleeding disorder or anticoagulation
History of significant allergic reactions to injected solutions.
Acute spinal cord compression.
Fluoroscopy should not be used in epidural injections for women who are pregnant.
In patients with poorly controlled diabetes, the corticosteroid may transiently, but significantly, increase blood glucose levels.
Caution when performing injections in individuals who have a history of congestive heart failure because of the potential for steroid-induced fluid retention.
While numerous articles have supported the benefit of ESIs for LBP, other studies have disputed their efficacy.
Most of these negative studies did not use fluoroscopy and radiographic contrast to document accurate placement of the injected substance into the epidural space.
Studies report that without fluoroscopy and radiographic contrast confirmation, incorrect injection placement occurs in 30% of cases.
Patients who have had symptoms for less than 3 months have response rates of 90%.
In patients have had radiculopathy symptoms for less than 6 months, response decreases to approximately 70%.
Response decreases to 50% in patients who have had symptoms for over 1 year.
Patients with symptoms of shorter duration have more sustained relief than those with chronic pain.
Patients with chronic back pain may have a better response if they develop an acute radiculopathy.
Favorable factors for the use of ESIs include:those who have not had previous back surgery, who are not on workers’ compensation, who are aged younger than 60 years, and who are nonsmokers.
Acute radicular pain from lumbar disk herniation responds more favorably than does radicular pain from lumbar spinal stenosis.
There is efficacy of lumbar transforaminal epidural injections in patients with persistent sciatica from lumbar disk herniation or spinal stenosis.
ESIs in many patients can potentially obviate the need for hospitalization and surgery.
A prospective, randomized, double-blinded, controlled clinical trial on 55 patients with severe sciatica from spinal stenosis or lumbar disk herniations who had not responded to 6 weeks of conservative treatment and were considered to be surgical candidates.
In this study patients were divided into 2 groups; 1 group received lumbar epidural injection with bupivacaine and steroid, while the other group received only bupivacaine.
In the follow-up at 2-3 years only 23% of patients in the group that received lumbar ESIs needed surgery, while 67% of patients in the bupivacaine injection group underwent surgery.
In the follow-up at 5 years found that 17 (81%) of 21 patients surveyed still had still not opted for surgery.
This report demonstrated a benefit from lumbar ESIs in patients who had been diagnosed with lumbar spinal stenosis or herniated nucleus pulposus, with the injections helping to reduce the need for surgery.
A recent systemic review of 14 randomized and 10 nonrandomized studies on the efficacy of lumbar transforaminal epidural steroid injections for lumbar radicular pain (Manchikanti L et al):The results demonstrated that the efficacy is good for radiculitis secondary to disk herniation with local anesthetics and steroids and fair with local anesthetic only, efficacy is fair for radiculitis secondary to spinal stenosis with local anesthetic and steroids, and efficacy is limited for axial pain and postsurgery syndrome using local anesthetic with or without steroids.
35% of patients with symptomatic lumbar spinal stenosis who received caudal ESIs, an improvement of 50% or greater was seen (Barre), and long-term treatment success was seen in 35% of patients after a mean follow-up of 32 months.
A systematic appraisal of caudal epidural steroid injections included randomized trials and 5 nonrandomized studies concluded that for lumbar disk herniation, the efficacy is good for short- and long-term relief of chronic pain secondary to disk herniation or radiculitis with local anesthetic and steroids and is fair with local anesthetic only.
Lumbar interlaminar epidural injections efficacy is good for radiculitis secondary to disk herniation with local anesthetics and steroids and fair with local anesthetic only, whereas it is fair for radiculitis secondary to spinal stenosis with local anesthetic and steroids and fair for axial pain without disk herniation with local anesthetic with or without steroids.
The lateral parasagittal interlaminar epidural approach has higher rate of contrast spread into the anterior epidural space.
Evidence favors the use of transforaminal ESIs in the lumbar spine compared with the cervical spine.
The transforaminal route is presumably more reliable for delivering the steroid to the affected area in cases of disk herniation in which the disk comes into contact with the nerve root.
The Spine Patient Outcomes Research Trial (SPORT)-a prospective, multicenter study of operative versus nonoperative treatment of lumbar intervertebral disk herniation.
The SPORT trial demonstrated a significant difference in the preference for surgery between groups:19% in the ESI group compared with 56% in the non-ESI group.
In this study there was no difference was noted in primary or secondary outcome measures at 4 years between the groups.
There was a higher percentage of patients changed from surgical to nonsurgical treatment in the ESI group (41% vs 12% in non-ESI.
In a study involving individuals with a lumbar disk herniation of greater than 25% of the cross-sectional area of the spinal canal; the patients were administered ESIs one level above the herniation: 42-56% of these individuals reporting the treatment to be effective.
For those who underwent an initial trial of ESIs, the delay in surgical decompression was not found to be detrimental to neurologic recovery at time of follow-up (Butterman).
No randomized, controlled trials have been performed to date on the efficacy of ESIs for the cervical spine and treatment of upper limb radicular pain.
Transforaminal cervical ESIs are preferred over the interlaminar approach because the transforaminal cervical injections allow for the delivery of higher concentrations of medications to isolated nerve roots and neuroforamina where stenosis may be present.
Cervical interlaminar epidural injections concluded that such injections are effective for relief of cervical radicular pain in the upper limbs.
Injection without fluoroscopic guidance results in 30-40% of needle misplacements, such as needle tip placement outside the epidural space and placement not at the presumed level of pathologic process.
It is s recommended that ESIs be performed under fluoroscopic guidance and with radiographic contrast documenting appropriate placement.
Fluoroscopy in conjunction with contrast is used to improve efficacy and minimize potential complications.
Live fluoroscopy is recommended during contrast injection for confirmation of lumbosacral transforaminal epidural injections.
The chance of significant complication from ESIs is remote.
The more common risks from lumbar epidural injections are as follows: backache, postural puncture headache, 0.5-1% for lumbar interlaminar injections and 0.6% for caudal epidural injections, nausea, vomiting, dizziness, and vasovagal reaction.
Bleeding in proximity to the nerve roots and/or the spinal cord is a rare but potentially serious complication.
Epidural hematoma occurs in 0.01-0.02% of procedures.
Infection is a rare complication.
Severe infection, e.g., epidural, abscess, discitis, osteomyelitis, meningitis may occur in 0.01% to 0.1% of spinal injections and epidural hematomas in fewer than one and 150,000.
Nerve root injury is also a rare event.
Mild hypothalamic-pituitary-adrenal axis suppression has been reported from 1-3 months after receiving epidural injections.
Up to 10% of persons who receive epidural steroids, may have suppression of morning cortisol levels.
Anterior cord syndrome can rarely result from the injection of particulate steroid into the artery of Adamkiewicz that supplies the anterior spinal artery feeding the anterior two third of the spinal cord in the thoracolumbar region
Cervical ESIs carry similar risks, that often results in greater impairment than damage at the lumbar levels and may precipitate respiratory arrest at higher cervical levels.
There is also a risk of spinal cord trauma that is essentially absent at the lower lumbar spine, since the spinal cord terminates at the level of L2.
Compression of the spinal cord may occur from from an epidural abscess or an epidural hematoma.
Complications are minimal when ESIs with proper equipment, training, and technique.
Digital subtraction angiography is able to pick up more venous flow and nonvisible arterial flow during cervical transforaminal ESIs, and is recommended to increase safety.
Complications of ESIs can probably be averted by using fluoroscopic guidance, contrast enhancement to avoid vascular uptake, nonparticulate corticosteroid, and a test dose of local anesthetic before injection of corticosteroid.
The optimal timing of epidural injection is unknown.
The early use of epidural steroid injections can be considered in patients with severe radicular pain that does not respond even to opioid medication or in whom the pain is severely interfering with sleep habits and daily functioning.
Early ESIs also carry the theoretical benefit of controlling inflammation and of preventing permanent neural damage, such as nerve fibrosis from the prolonged inflammatory process.
The interval between injections varies with the steroid preparation used.
The ideal number of epidural injections to be administered for a given clinical scenario is unclear.
Up to 3-4 injections may be used for acute radicular pain syndromes, with reeevaluation by a physician to determine the need for additional procedures
There are no medical outcome studies to clearly support more than 3-4 injections.
Epidural steroids are injected in a diluent, such as lidocaine (1-2%) and/or normal saline.
For interlaminar ESIs, the typical corticosteroid doses administered are 12-18 mg for betamethasone and 80-120 mg for methylprednisolone.
Half of these steroid doses are generally administered when performing transforaminal ESIs
Generally, in cervical and thoracic epidural injections, a total volume of injectate is 3-5 mL is used for ESIs using the interlaminar approach.
In cervical and thoracic transforaminal ESIs, a total volume of only about 1.5-2 mL is used.
The volume used for lumbar ESIs is generally being 6-10 mL for interlaminar ESIs, up to 20 mL for caudal ESIs, and 3-4 mL for transforaminal ESIs.
Cervical and thoracic epidural injections can be carried out using interlaminar and transforaminal approaches, while lumbar epidural injections can be performed using 3 approaches: transforaminal, interlaminar, and caudal.
Interlaminar epidural injections
Interlaminar epidural injection refers to injection into the epidural space and can be performed through paramedian or midline approaches.
With the ligamentum flavum penetration a loss of resistance technique is implemented with saline until proper advancement results in penetration into the epidural space.
Lumbar interlaminar approach contrast media studies indicate 36% of the injections spread into the ventral space, unilateral flow was observed in 84% of the injections, and the amounts of cephalad and caudad flow averaged 1.28 and 0.88 levels, respectively.
The transforaminal approach occurs by placing the needle under the pedicle in the neuroforamen, superior and ventral to the dorsal root ganglion and exiting nerve root.
Caudal lumbar epidural injections are performed by inserting a needle through the sacral hiatus into epidural space at the sacral canal.
Medication composite for an epidural injection consists of a steroid preparation and, in most cases, an anesthetic.
A contrast medium also is generally used, along with fluoroscopic-guided procedures, to verify placement and distribution of the injectate.
A local anesthetic’s time to onset of action can be decreased by buffering the anesthetic with bicarbonate) and increasing its concentration.
Typically, 1% lidocaine is used as a skin anesthesia for epidural steroid injections
Different steroid preparations are used including dexamethasone (Decadron), triamcinolone (Kenalog), betamethasone (Celestone), and methylprednisolone (Solu-Medrol).
The fact that corticosteroids differ significantly in microscopic size:
Dexamethasone – Particles were 5-10 times smaller than red blood cells, contained few particles, and showed no aggregation.
Triamcinolone – Particles varied greatly in size, were densely packed, and formed extensive aggregations.
Betamethasone – Particles varied greatly in size, were densely packed, and formed extensive aggregations.
Methylprednisolone – Particles were relatively uniform in size, smaller than red blood cells, and densely packed and did not form very many aggregations.
Corticosteroids dexamethasone and methylprednisone are equivalent in efficacy and adverse effects in the treatment of lumbar radiculopathy by lumbar epidural injection
Caudal epidural injection with local anesthetic with or without steroids was found to be effective in patients with disk herniation or radiculitis, although relief with first and second procedures was significantly higher in the steroid group at 1-year follow-up.
Most patients take several days to respond to ESIs.
The use of epidural steroid injections in conjunction with a properly designed rehabilitation program may play a very important role in the conservative management of patients with severe radicular pain, improving their quality of life and function.
May have little or no benefit outside a 2-6 week window following its administration.
Epidural injections may contain lidocaine and/or steroids, and may be considered for short-term pain relief or to delay surgery in lumbar spinal stenosis, but their benefit is considered small.
Does not provide long term pain relief and does not prevent surgical intervention.
Use of steroids compared to analgesics alone such as bupivacaine usually of questionable significance.
Studies have revealed that at 24 hours postinjection, at 3-6 months, or 1 year later have no impact on day to day function, need for surgery, or long term control of pain.
There are two approaches to the epidural space: 1-the interlaminar approach in which the tip of the needle is placed in the posterior epidural space and 2-the transforaminal approach in which the tip of the needle is placed in an intervertebral foramina where the spinal nerve exits the spinal canal.
In the interlaminar approach the drug is injected in the posterior epidural space whereas in the transforaminal approach the drug is placed in close proximity of the spinal nerve and dorsal root ganglion and spreads laterally and anteriorly to the epidural space, the interspace between the spinal nerve and the herniated disk.
The transforaminal approach is used when a single nerve root in one extremity is affected from a single lateral herniated disc and the interlaminar approach is used when several spinal nerves are involved in one leg or in both legs, as in a central herniation.
Epidural steroid injection used are primarily particulate steroids and include methylprednisolone, triamcinolone or
Complications are usually minor and transient.
Complications occur in 0 to 17% of cases when performed on the neck, but most are minor.
Major complications are rare and include aseptic meningitis, bacterial meningitis and epidural abscess.
The above complications may occur more frequently and immunosuppressed patients.
Rarely catastrophic CNS injuries may occur and include paraplegia, quadriplegia, medullary infarcts, cerebellar infarct, and death.
Transforaminal injections of epidural particulate steroids have resulted in cerebrovascular occlusions probably from intravascular injection of the particulate steroid through arteries that communicate with the anterior spinal artery, resulting in segmental cord infarcts.
Fungal meningitis has occurred from injection of contaminated compounded methylprednisolone acetate.
Epidural steroid injections in the cervical epidural space have resulted in spinal cord injuries.
The above complications may occur more frequently and immunosuppressed patients.
Infectious disease outbreaks associated with such injections have rarely been reported.
Epidural steroid injection is the first line of treatment in patients with spinal pain.
MRI does not improve outcomes in patients with lumbosacral radiculopthy in patients who are candidates for ESI and has only minimal effect on decision making (Cohen SP et al).
In a study comparing patients with lumbar spinal stenosis who underwent ESI with patients who also had LSS but did not receive ESI, and followed for 4 years: Patients who had received ESI and subsequently underwent surgery for their LSS were found to have an average 26 minute increase in operative time and nearly 1 full additional inpatient day compared with those who had surgery but did not undergo ESI at the outset of the study (Radcliffe K et al).
In the above study those who had ESI were more likely to undergo surgery than those who did not, and for those who did not undergo surgery, those who had ESI had less improvement in pain and physical function than the non-ESI group at the end of the 4-year study.
The above study suggests ESI might actually exacerbate stenosis by introducing additional material into an already compromised site or in some other way damage nerve roots.
ESI administration above the affected nerve root may result in superior outcomes to those administered at the same level as the abnormality, and this is attributable to the extensive segmental spread that occurs with an injection, and the unit steroid dose typically use is much higher than what is necessary (Jeong HS et al, Owlia MB et al).
Compression of nerve roots by disc herniation regarded as the source of radiating pain to arm or leg, but release of chemical mediators, such as phospholipase A2, from a herniated disc may also play a significant role.
Prostaglandins and leukotrienes sensitize pain receptors and enhance pain generation in spinal pain.
Steroids inhibit phospholipase A2, and limit the formation of leukotrienes, and prostaglandins.
Epidural injections are associated with small risks of important adverse events: infection with epidural abscess, discitis, osteomyelitis, meningitis, may occur in .01 to 0.1% of spinal injections and epidural hematomas in fewer than one in 150,000.
10% of patients who receive epidural steroid injections have a suppression of morning cortisol levels.