Introduction: to describe the pitfalls and failures of a common pre-surgical diagnostic pathway, ie epidural steroid injections and facet injections to isolate the source of a patient’s pain.
Background: multilevel, degenerative disc disease appears on an MRI of most patients after a certain age. Back pain is also very common, but physicians are often unable to reliably pinpoint which specific disc causes a patient’s pain, especially if there is no neurological component, or “sciatica”. To say in another way: when a patient has pain in his back while sitting, that is associated with sciatica in the back of the thigh, back of the calf or bottom of the foot, an experienced surgeon will immediately recognize that this patient’s pain is in the distribution of the S1 nerve root. Nerves begin in the brain and traverse the spine on the way to the extremities.
When a nerve is irritated in the spine, a patient will feel pain in the direction of wherever that nerve courses. hence, pain in the back of the thigh, would indicate that the bottom disc or specifically L5 S1 is causing the patient’s pain. However, there are a number of situations such as pain in the back without sciatica that make it very difficult to pinpoint exactly which disc is the culprit. A well-established method of isolating the painful source is a diagnostic, epidural steroid injection. An epidural steroid injection implies introduction of a needle in the vicinity of a pathological disc and injecting a combination of a local anesthetic and possibly a steroid.
The local anesthetic numbs the painful source, and if that source is indeed the cause of patient’s pain then immediately after the injection, the patient will report significant diminution in their pain – this functions as a confirmation for treatment. I have employed this methodology for the past 11 years and have treated thousands of patients with successful outcomes. Patient are often surprised how I’m able to take care of their multilevel degenerative spine with a single level surgery. There is no magic – just some diligent preoperative verification. However, over the years, I have recognized a number of scenarios where a preoperative injection may produce false positive or false negative results. It is important to recognize these scenarios and account for the pitfalls in the surgical planning, and in the diagnostic process. The following is a review of pitfalls of using pre operative injections to help make the correct diagnosis.
Foraminal Stenosis
Patience with phenomenal stenosis often present with continuous or intermittent lower extremity pain without neural claudication‘s, or difficulty walking specifically. They will report lol extremity pain in all positions, especially with flexion. A properly placed transforaminal epidural steroid injections, relies on the intravertebral space specifically between the particles. Which significant diminution of this kite that space is diminished as well. Went through the compounded by a bulging disc , there is diminution of anteroposterior dimension of that space as well. They transfer aminal, epidural steroid injection may be impossible if the degree of stenosis prohibits the egress of fluid into the spinal canal. This may clearly produce a false negative result I have seen numerous patients with isolated single disc pathology, who underwent a transforaminal epidural as part of the conservative care. I was surprised to find absence of significant improvement immediately after the epidural steroid injection, contrary to what I expected. A reasonable solution to this issue is to substitute a transforaminal epidural steroid injection with a well-placed, central epidural. Keep in mind that a central epidural delivers the medication further away from the” disk– nerve interface” and hence may still yield lower than expected results.
Local steroid effect: there is a sub group of younger patients with early degenerative discs and significant pain that may fall into a different pitfall with diagnostic injections m. specifically, these are very much sensitive to the effect of steroids. A trigger point, a facet injection, as well as a central epidural with significant spreading of the medicine locally may produce a local anti-inflammatory effect on the disks that are adjacent to the actual level of the injection.
This is especially problematic in patients with minimal pathology and severe pain a small anti-inflammatory contribution mean yield dramatic early results, which may be mistaken for a positive response to an injection – a false positive result. This is especially true if there is concurrent, absence of neurological pathology, i.e. sciatica, and the patient complains of primarily back pain or neck, pain, with associated muscular spasms. A reasonable solution to this potential pitfall is to avoid the steroids in the injection and use only lidocaine, i.e. a local anesthetic.
This will, unfortunately, miss an opportunity for long-term relief that’s commonly provided by the steroid. So as not to rob the patient of an opportunity to get better with conservative care, I would propose diminished reliance on epidural, steroid injections. If the patient feels conservative care, then diagnostic injections should be undertaken separately as opposed to relying on the immediate effect of the therapeutic injections by using lidocaine only in lower quantities, one avoids a local steroidal effect that is similar to intramuscular injections. This liberates the diagnostic from the therapeutic process and avoids a potential bias from the local effect of steroids.
Discogenic Back or Neck Pain
Another common source of false negative or equivocal results after diagnostic epidural steroid injections may be seen in patients with purely axial neck or back pain. These patients will often report worsening low back pain with sitting or standing; or worsening neck pain while sitting back in the sofa , or while reading in bed. A commonly accepted source of pain in these patients is the degenerative disc hence their penis worse with any activities that in part, a kyphotic posture or load the desk. If the intravertebral disc has lost some of its tensile and compressive strength, when it is loaded in flexion, it will produce the pain that is centered around the neck, or the lower back, and if there is no neurological compression or irritation, then these patients will deny any extremity symptoms.
These clinical symptoms are “mechanical” in nature, since the symptoms are dependent on the position and body mechanics. An epidural steroid injection delivered via the transforaminal or even more so central method, may result in a false negative result, since there is very little penetration of the disc by the medicine. a proposed alternative for patients with isolated EXO neck or back pain is to consider intra-discal lidocaine injections. Introduction of lidocaine into the disc May have some negative effects on the hyaline cartilage similar to eat negative affect on shoulders and knees, so it is important to discuss the risks of these injections.
Furthermore, an intro, disco penetration by a needle has been shown to expedite disc degeneration in a rabbit model, and has been further shown to expedite adjacent level degeneration in patients after neck surgery. Finally, there is an important additional risk of discitis that is caused by an intro discal injection, hence, an addition of antibiotics, IV, is reasonable in conjunction with the intro discal injection. An awareness of a false negative result with isolated axial, neck and back pain may aid a treating surgeon in understanding a patient’s lack of positive response after a diagnostic epidural injection and make prompt and alternative intradiscal injection.
Conclusion:
Transforaminal epidural steroid injections, central epidural steroid injections and intra-discal injections are an important diagnostic modality to help a treating surgeon, understand the source of his or her patient’s pain. These injections provide a glimpse into the potential post operative future and should provide a surgeon much needed confidence before counseling a patient regarding the likely outcomes of surgery these injections may allow a treating surgeon to avoid treating unnecessary levels that are degenerated on an MRI but are not the source of the patient’s pain.
Since my practice is focused to a large extent on helping patients after failed spine surgery done elsewhere, I frequently employ diagnostic injections to figure out whether my patient has pain from above, or below their old surgical site, or to understand if levels of potential pseudoarthrosis are indeed a source of the patient’s pain or are simply radiographic findings consistent with “locked non-union“. a properly targeted injection purports minimal risk and allows me to sleep well at night before difficult surgery.
