In Part 1 we discussed lumbar epidural steroid injections (ESI). Part 2 covered facet-directed lumbar injections and their purpose. In Part 3 we will address the cervical ESI.
A cervical epidural injection involves a provider inserting a needle into the epidural space and injecting a medication. Due to the spinal cord residing in the cervical segment, x-ray (fluoroscopy) to identify the target level is critical. Cervical ESIs may be more dangerous than lumbar.
Today, the most common medication is a steroid, although it should be highlighted that even epidural steroid injections (ESI) are not Food and Drug Administration (FDA) approved. Rare but serious problems have occurred after injection of corticosteroids including loss of vision, stroke, paralysis and death. Nonparticulate corticosteroids may reduce the risk of injury to the brain and spinal cord. Dexamethasone may be preferred over other steroid options.
Just as in the lumbar spine, the effectiveness and safety of ESIs have not been established, however some research has shown benefit.
The known indications for ESI are radicular (arm) pain and not axial neck pain. That is, pain isolated to the neck is unlikely to improve with an ESI. Pain down the arm has a better chance. Weakness and sensory deficits are less likely to improve from ESIs. Additional criteria usually include:
- Evidence of nerve root compression on MRI which correlates with the clinical findings
- Pain that has not responded to at least 4 weeks of conservative management
Of course, conservative management should include a combination of strategies to reduce inflammation, alleviate pain, and improve function. This includes physical therapy and possibly chiropractic care, acupuncture, cognitive behavioral or massage therapy. This also usually includes anti-inflammatory medications and analgesics. Documentation of compliance with a plan of therapy is helpful. Usually, about 3 months of conservative therapy is considered an adequate trial.
A cervical ESI can be performed in a few ways. Just as in the lumbar spine, cervical ESI can be delivered interlaminar or transforaminal. Interlaminar (IL) approaches the epidural space from the posterior spine between the two vertebral lamina. A transforaminal (TF) approach delivers medication through the intervertebral foramen. However in the cervical spine, the TF injection is performed with the patient laying on their back (supine), as opposed to their belly (prone) in the lumbar. The cervical needle is advanced the needed to the posterior aspect of the neural foramen to avoid vascular penetration and devastating side effects, so the cervical TF injection does not reach the ventral epidural space like the lumbar.
In comparing IL to TF routes, the effectiveness seems about similar, and the IL may be a bit safer. Therefore many proceduralists favor cervical interlaminar ESIs over TF.
IL approaches are usually performed at C6- or C7-T1 because the epidural space is narrower at higher/ rostral levels, increasing the risk. However C3-4 and C4-5 IL approaches are possible pending consideration of the individual patient’s MRI.
Following an ESI, a pain diary is important. Pain diaries are a critical component of tracking pain fluctuations, including changes before and after procedures. Reliance of self-report measures on recall of past pain can lead to reliability problems, since current pain significantly influences memory for past pain. There is nothing indelibly specific about the mark pain leaves on our hippocampus.
The immediate and delayed pain response(s) could have diagnostic implications, as well as treatment predictive value, and represents a powerful tool for patient selection or planning. The immediate response to an epidural injection likely reflects the reaction to the anesthetic,while a delayed response may be to the steroid. The anesthetic portion serves as a diagnostic block, and pain elimination is usually interpreted as accurate targeting of the pain generator. The local anesthetic may have action on the epidural, neural or perineural pain generator’s immediate nerve supply. In patients without an immediate or delayed improvement, the anesthetic may not have come in direct contact with the injectant, or the pain generator may be different from the area targeted. In patients with a partial immediate response, there may be more than one pain generator, with only part of the pain problem being exposed to the anesthetic. In patients with no immediate response, but a positive delayed improvement, again the pain generator may be resistant to the local anesthetic, may not be in contact with the local anesthetic, or the delayed response showed improved pain from a systemic steroid reaction.
For an ESI to be considered successful, there should be at least a 50% sustained improvement, using the same scale, for at least three months. If a patient fails to respond well to the initial ESI, a repeat ESI after 14 days can be performed using a different approach, level and/or medication. We used to limit the number of ESIs per year, however repetition may be more regulated by the amount of steroid used and actual response. There can be medical problems associated with repeat steroid exposure
ESIs are not intended to disintegrate a disc herniation, per se. Their benefit, not matter what modality, is to improve symptoms while the body naturally heals itself. Disc herniations can resorb on their own. Other pathologies compressing nerves can improve.
Regenerative therapies are primarily described for the lumbar spine.
Cervical ESIs are a reasonable interventional option for arm pain failing other conservative trials. They are not indicated for everyone with pain. Primarily, steroids are used. Tracking the response to an injection is critical. Many patients claim the pain returned and therefore deem this a failure. While this may be true, tracking the actual pain changes with a diary may show a diagnostic indication that simply did not become therapeutic.
Injections are unlikely to be permanent in-and-of themselves. They may simply improve pain and function while the body heals itself. They may be diagnostic preview, to support more invasive treatments. They may be repeated in certain scenarios. But most importantly, failure of epidural injections does not necessarily mean surgery is the next step. Failure of an injection may indicate surgical conversations may commence. However failure of an injection may also indicate surgery will not be helpful.
Failure of a prior injection does not necessarily predict a response to current symptoms. The spinal pathology may be completely different, and therefore a new injection may benefit a new structural change. A chronic spine issue may not have previously been responsive, but now susceptible.