Summary of Key Points
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Despite a geometric increase in the utilization of selective spine procedures and spine surgery, between 1990 and 2010 low back pain and neck pain increased the years-live-with-disability (YLD) factor. Use of procedures to address pain without addressing causes of disability and loss of social role consistently demonstrates inferior outcomes.
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Selective spinal procedures show greater efficacy in treating radicular pain than in treating axial low back or neck pain. There is no evidence that epidural steroid injections improve functional outcomes in axial low back pain.
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Radiofrequency ablation should not be performed without two diagnostic medial branch/dorsal rami blocks providing > 80% relief.
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Thermal intradiscal procedures show benefit in only a select group of people.
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Multiple procedures performed without an intervening office visit (“series-of-three”), procedures performed without advanced imaging (magnetic resonance imaging or computed tomography), procedures performed without image guidance (blind procedures), and failure to document outcomes between procedures are all hallmarks of poor quality. The clinician should consider sending patients to an alternate provider if these factors are present.
Since the 1980s, utilization of percutaneous spinal procedures to avoid surgery has shown a geometric increase. In an era of value-based health care, pressure to address beneficial outcomes and the relative cost has brought scrutiny to the entire field of spine care. Pain and disability from spinal pathology, including radiating arm and leg pain, are usually benign and self-limited. The majority of acute neck or low back pain resolves within 90 days. For patients with substantial functional disability primarily caused by pain in the neck, low back, upper or lower limbs with mild/minor neurologic deficits, spinal injections have been demonstrated to be an effective part of a multimodal treatment regime to return patients to function. By combining early activity, physical therapy, and possibly injections, there are data demonstrating return to function.
As with every other chapter of this book, the author’s intent is to enhance the wisdom of the physician. The physician’s ethical duty is to always weigh the risk-benefit ratio with a systematic plan to minimize the invasiveness and risk to the patient if spontaneous symptom remission is likely. Significant, additional findings regarding risks, benefits, and concerns have resulted in some reevaluation of spinal procedure efficacy and appropriate utilization.
Overview of Select Spinal Procedures
The intended benefit of all spine procedures is greater function for the individual as well as decreased direct costs (medication, appliances, procedures) and decreased indirect costs (lost work time, decreased productivity, biopsychosocial distress). The increased utilization of selective spinal procedures has not reduced the global burden of disease. The implied social contract is that increasing expenditure around a particular event should decrease total expenditure around the entire episode of care. That finding has proved illusory in Western countries. A long-term approach that includes education, early return to physical activity, sleep hygiene, frequent doses of quota-based aerobic and anaerobic activity, and appropriate follow-up that emphasize the difference between hurt and harm have good evidence in the literature to reduce the burden of chronic spine pain.
Epidural Spinal Injections
Epidural injections should be utilized only with concordant confirmation of subjective, objective, and radiologic evidence of cervical, thoracic, or lumbar radiculopathy with no greater than minimal/mild neurodeficit. Formal physical therapy or a home exercise program should be tried 2 to 4 weeks before obtaining advanced imaging or performing an injection. Multiple societies have recommended that limb pain exceed axial back or neck pain. Advanced imaging (magnetic resonance imaging [MRI] or computed tomography [CT]) has been shown to reduce complications and likely reduce the number of procedures. There is no role for a preplanned “series-of-three” epidural steroid injections. Repeated injection should be based on greater than 50% relief in limb symptoms and one standard minimal clinical difference (MCD) improvement in any of the available outcome measures (Patient Disability Questionnaire [PDQ], Patient-Reported Outcomes Measurement Information System [PROMIS], EuroQol-5D [EQ-5D], Neck Disability Index [NDI], Oswestry Disability Index [ODI], etc.) for a minimum of 30 days. Care should be taken to evaluate for potential alternative diagnoses (hip, shoulder, tumor, peripheral neuropathy) or confounding diagnoses including central sensitization, chronic pain, and disabling depression/bipolar conditions, as these circumstances will markedly lower the efficacy of procedure.
Interlaminar Epidural Steroid Injection
Interlaminar epidural injections can be performed in the cervical (lower), thoracic, and lumbar levels. The lumbar interlaminar epidural injection may be performed with and without glucocorticoids and is widely utilized to decrease pain associated with divergent diagnoses: childbirth, surgical procedures, or spinal pathology. When performed with proper care, the procedure has a few well-described risks that constitute 0.5% to 3% of procedures. An interlaminar injection has too little specificity to provide meaningful diagnostic information. There is difficulty directing medication to a specific site of pathology using the interlaminar approach. Positioning the needle in the epidural space without a subarachnoid flow of medication (or postprocedure spinal headache) should be the primary concern. Many clinicians will utilize a “paramedian” approach in attempt to direct the needle and medication toward the more impacted side.
Although interlaminar epidural injections are utilized more frequently (by four-fold) than other approaches, there appears to be a greater complication rate associated with epidural hematoma, although there is similar efficacy. The epidural space is often a potential space whose upper volume boundary is defined by the volume of cerebrospinal fluid (CSF) in the subarachnoid space. Specifically, if stenosis is present without visible CSF (on axial MRI or CT images) at a particular level, this would be a poor location to depot steroid medication. The steps for getting good results from interlaminar epidural steroid injection are similar to those for other techniques. First, plan the procedure by taking a history, performing a thorough physical examination, and correlating that information to appropriate imaging. As stated previously in this chapter, if the predominant complaint is axial back pain, the chance of a medium or long-term, nonplacebo yet beneficial result from depot of steroid in the epidural space is low. Alternatively, when the pain presentation is predominantly in the limb, and subjective complaints correlate with discreet pathology on radiology, the chance of injection benefit is high with implication of surgery avoidance in a select population.
Preprocedure planning for an interlaminar approach should include the use of advanced imaging to verify that adequate epidural fat (CSF) is present at the level of approach and to assess the thickness of the ligamentum flavum. Additionally, knowledge of operative sites, of causes of dural ectasia, and of causes of bleeding diathesis is critical. These steps will help reduce the rate of needle-tip misadventures or other harm to patients.
Once planning is complete, the procedure is straightforward. Fluoroscopic guidance assists in identifying the appropriate level in the lumbar, thoracic, or cervical spine and minimizes harm to the patient. The skin overlying the interspace between the spinous processes is anesthetized and a blunt-tipped needle (the most commonly used equipment for this procedure) is passed through the skin and directed midline or paramedian. Care should be taken to avoid the needle crossing the midline, as the diameter of the epidural space decreases the more lateral the needle tip travels. Combining a direct, fluoroscopic visualization and “loss of resistance” technique with a syringe containing water or air to advance the needle decreases the incidence of spinal headache by dural puncture. Incidence is minimized (but not eliminated) by skillfully combining these techniques. A strong understanding of anatomy is vital for this procedure, as the thickness of ligaments, the depth of lateral recesses, and the location of vascular anatomy changes throughout the course of the spine. Additionally, the orientations of spinous processes are different in cervical, thoracic, and lumbar spine divisions. To obtain an efficacious result, medication needs to be placed in the epidural space only. Use of nonionic contrast is strongly recommended to verify placement once “loss of resistance” is encountered, as a “ false loss of resistance” may be encountered between the interspinous ligament and ligamentum flavum in the hands of even experienced physicians. More problematic, tissue can become lodged in the bevel of the needle resulting in a failure to perceive loss of resistance and leading to inadvertent dural puncture and a contrast flow pattern identical to a myelogram. Catastrophic case reports of spinal cord puncture during cervical and thoracic interlaminar epidural injections exist. Changing the fluoroscopic view or placing a small amount of contrast is paramount in order to verify needle location should the needle appear to pass the spinolaminar line without loss of resistance. The epidural space is not uniform, and the pyramidal cross-section shape means the likelihood of dural puncture, cord injury, or vascular injury increases the farther the needle travels out laterally. Additionally, McGoldrick expanded on the cryomicrotome dissection work of Hogan to show that failure of ligamentum fusion in the posterior midline that occurs in the cervical and high thoracic space is 51% to 74%. Above the C7-level, there is controversy about whether a “fat pad” exists posteriorly above the dura mater, if there is ligamentum coverage or the uniformity of the epidural space during normal respiration in the upper cervical spine. Complications of dural puncture with infusion of anesthetic intrathecally can range from slow onset respiratory depression (~30 minutes) to seizure and cardiovascular collapse. The compelling data that < 25% of blind attempts (without fluoroscopic guidance) by experienced anesthesiologists placed medication at the site of pathology may account for the jaundiced view held by many referring physicians with regard to the efficacy of injections when the majority of procedures in the early 2000s were blind. The prosaic use of the interlaminar technique has value and often provides less specific findings.
Complications of Interlaminar Epidural Steroid Injections
Although bleeding and infection still are the most common complications of any injection, neuraxial procedures have a potentially devastating risk of epidural hematoma or acute spinal cord injury (cervical and thoracic levels) and meningitis. Overall, minor and major complications account for an estimated 0.32% to 1.6% of epidural procedures. Authors have suggested that the proper use of fluoroscopic guidance may help reduce 45% of catastrophic interlaminar complications. Meningitis or formation of epidural abscess can produce similar effects of compression caused by epidural hematoma along with systemic signs of infection. In October 2012, batches of steroid from compounding pharmacies were contaminated with fungus, leading to nearly 50 deaths and 720 confirmed cases. Finally, many catastrophic complications have occurred when patient was sedated for the procedure. Multiple societies have recommended that cervical procedures should be done with the patient conscious, communicating, and still responsive to verbal or tactile stimuli.
Transforaminal Epidural Steroid Injection
The transforaminal technique is used with increasing favor owing to beliefs around the selectivity, proximity (to the pathology), and longevity of benefit. However, the superiority of this technique is difficult to substantiate in the literature. Riew and colleagues published two very persuasive studies that were shrewdly designed to eliminate the winner’s bias seen in many injection versus surgery studies. All patients were scheduled for surgery and randomized to receive a transforaminal injection of either anesthetic alone or anesthetic + steroid. Of those receiving steroid via transforaminal delivery, 71% elected to not have surgery at end points 13 to 27 months. This was statistically significant compared to the anesthetic-alone group where only 33% elected not to have surgery by the end point (p value < 0.004). This finding held out at a 5-year analysis with three of four patients requiring late surgery (between 27 and 73 months) with progression of symptomatic spinal stenosis. The study by Manon and colleagues suggested that transforaminal epidural steroid injections may be surgery sparing in up to 56% of patients with lumbar disc herniation.
The transforaminal technique is more selective. Even when the technique provides less than optimal long-term results, surgical success rate is often higher secondary to the positive predictive value of the transforaminal technique ( Fig. 107-1 ). Unlike interlaminar injections, transforaminal injections can provide some diagnostic information. Evidence has shown that patients can get long-lasting relief if the medication is placed on the ventral aspect of the pathology involving minimal neural compression. The transforaminal technique is highly dependent on image guidance, bony landmarks, and physician acumen for needle placement to avoid patient harm. The proximity of vasculature, neural elements, and dura mater require proprioception, perspicacity, and judgment to obtain the best results. As with all spinal procedures, a thorough history, physical examination, and review of imaging to determine the concordance of limb symptoms are the most important elements of the procedure. Additional caution should be taken in reviewing the images to confirm aberrant vasculature locations, adequate epidural fat, or conjoined roots in proximity of the target neural foramen to avoid injury. Once the procedure begins, the corresponding superior end plate is squared with cranial or caudal tilt and the fluoroscope is adequately obliqued so that the foramen is visualized under the pedicle. Once properly aligned, the needle is advanced in line with the fluoroscopic beam and directed to the subpedicular space. Care should be taken not to extend the needle medial to the 6 o’clock position of the pedicle due to the risk of dural puncture. The needle position should be assessed in at least two fluoroscopic views (often anteroposterior, lateral, or contralateral oblique views). Once the contrast is injected, an ideal contrast pattern should show medial flow of the contrast to the pedicle and along the nerve root. Care should be taken not to inject the nerve root itself with the medication.
Diagnostic Nerve Root Blocks and Other Diagnostics
Diagnostic selective nerve root blockade is one of the mainstays of diagnostic injections. The approach is similar to the transforaminal epidural steroid injection described earlier, with several important differences. The main differences include lateral placement of the needle tip, limiting anesthetic volumes, corroborating location rigorously with live contrast (no epidural or intravascular flow), and verifying of extraneural placement of the needle tip. Violation of any of these principles may lead to unintended proximity anesthesia and decreased positive predictive power of the procedure. Yeom and colleagues elegantly demonstrated with blocks of affected and unaffected nerve roots that the diagnostic predictive value of selective nerve blocks approaches 80% when the best-practice principles are adopted. These tests, like virtually all diagnostic tests in medicine, should be used in conjunction with other information to maximize benefit for the patient ( Fig. 107-2 ).
In the differentiation of hip/spine syndrome, the use of either selective nerve root blocks or diagnostic intra-articular injections has both been shown to increase positive predictive value and decrease the likelihood of unnecessary surgery. Anesthetic intra-articular hip injections have shown 95% positive predictive value for forecasting relief from hip surgery even in the presence of buttocks pain. Other authors have shown 99% sensitivity and 81% specificity differentiating hip/spine pathology in the presence of equivocal radiology. Similar extrapolations are applied to shoulder neck syndrome, although the data are less robust.
Use of fluoroscopy and documentation of outcomes (usually with use of a pain diary) between injections with a minimum of 30 days of 50% improvement is considered standard of care. Consistent repetition of the same injection at the same site with less than a 30-day interval, failure to document fluoroscopic visualization, failure to use outcome measures, or consistent use of a “series-of-three” may be indications of inferior quality. Finally, epidural injections in general and transforaminal injections in particular show inferior long-term results in treating axial-back pain or spinal stenosis. Although there may be short-term pain benefits, there is no evidence that the procedures are surgery sparing or make a long-term outcome difference. Kennedy and coworkers compared the effectiveness of the transforaminal injections in reducing pain and functional restoration; their research showed 50% relief and 50% functional restoration in 70% of patients who received a transforaminal epidural steroid injection ( Fig. 107-3 ).
Complications of Transforaminal Injections
The growing use of pain procedures to avoid a surgery has resulted in catastrophic complications including death, persistent vegetative state, stroke, spinal cord infarction, and high anesthesia-related cardiorespiratory collapse. Direct injury to the spinal cord by transforaminal injections is extremely rare, but ischemic injury to the spinal cord has been reported when particulate steroids have been inadvertently injected into the radicular arteries supplying the spinal cord. Several safeguards exist and should be known by a fellowship-trained interventionalist—including the use of contrast enhancement to confirm needle-tip placement, use of “live” fluoroscopic visualization to confirm arterial uptake, use of test-dose anesthetic medication, use of digital subtraction technology, and keeping patients conscious to respond purposefully. Although each of these recommendations have merit, the most convincing evidence to modify current practice comes from an animal study demonstrating a zero infarction rate with administration of “nonparticulate” steroid in two different formulations, whereas 100% of the “particulate” steroid group suffered clinical neurologic symptoms that correlated with hypoxic and ischemic damage. Additionally, Kennedy and coworkers showed no statistical difference in pain and function at 2 weeks, 3 months, and 6 months comparing particulate and nonparticulate corticosteroid (dexamethasone compared to triamcinolone). Of note, the nonparticulate steroid group had a much higher risk of receiving three injections to achieve the same benefit as one injection in the particulate steroid group. Transforaminal epidural steroid injection still has a risk profile that is rare with evidence that procedures may be surgery sparing.
Caudal Epidural Steroid Injection
Caudal epidural injections are another method to access the epidural space for delivery of medication. This procedure may be used with or without a flexible catheter in an attempt to enhance selectivity and proximity to pathology. Although transforaminal or interlaminar injections have been considered superior, evidence may suggest the noninferiority of caudal injections for pain relief. Questions remain as to their relative selectivity. Another disadvantage of caudal procedures may be a limitation of benefit to lower lumbar or sacral pathology. A higher volume of medication is used to achieve equal benefit when compared to other approaches. Caudal procedures are chosen as an alternative to the above-mentioned approaches when access is difficult and surgery is not an option. Caudal epidural injections are safe in postsurgery syndrome with hardware. Placement of the needle for a caudal injection is best guided by a combination of palpable anatomic landmarks and image guidance, as there is a > 25% rate of needle tip misadventure without image guidance. The procedure is fairly simple with a blunt-tipped needle directed through the sacral hiatus assisted by a simple two-plane confirmation in anteroposterior (AP) and lateral views. The needle is advanced along the ventral side of the dorsal bony elements of the sacrum to approximately the S3-4 space, as the thecal sac typically ends around the S2 level, but occasionally extends as low as S4. Nonionic contrast material is used with fluoroscopy to confirm appropriate needle placement within the epidural space and outside thecal sac, as violation of the dura mater can result in a spinal headache. Injection of a steroid and anesthetic solution into the caudal epidural space may result in transient urinary retention. Finally, the concentration of corticosteroid is significantly less well distributed in the sacral epidural fat—a concentration decrement of 10-fold or more of the injectate reaching the site of pathology.
Other General Complications of Epidural Steroid Injections
Other potential considerations of epidural steroid injections are suppression of the hypothalamic-pituitary-adrenal axis secondary to the use of multiple steroid injections. Minor complications like contrast allergy, radiation exposure, and nerve injury should not be overlooked. Therefore, these procedures should be performed by a trained interventionalist.
In conclusion, epidural steroid injections show benefit when performed for the correct reason (radicular pain, not axial pain) and when medication is delivered to the correct location (fluoroscopic guidance and contrast confirmation). These injections have been shown to help reduce the surgical rate, allow for earlier return to function, and possibly save $12,666 per responder (1999 dollars) (Karppinen 2001, Schaufele 2006). Therefore, referring physicians should insist on the highest clinician acumen for the proper delivery of medication to the site of pathology.
Key Points
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To get the best outcomes, procedures should be performed by fellowship-trained interventionalists.
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Transforaminal epidural steroid injections (ESIs) may be considered over interlaminar injections if the desire is to increase specificity.
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Transforaminal ESIs can be used as diagnostic blocks to delineate the source of the pain.
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Doctors should be competent in resuscitation if any unwanted event happens.
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ESIs should not be performed purely for axial pain.
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A series of three injections is not recommended.
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Dexamethasone is the preferred steroid as a first-line drug.
Joint Procedures: Cervical, Thoracic, and Lumbar Facet Injections
The functional portion of the spine is divided into approximately 25 individual “motion units” that are composed of the disc and a matched pair of posterior joints. Colloquially, these joints are called the “facet joints” and are in constant motion providing both proprioception and resistance to excessive motion. These joints may suffer painful wear and tear like other diarthrodial joints as the forces born through these joints that can be measured in the hundreds of newtons. In addition to the facet joints (referred to a zygapophysial joints in lumbar spine) and uncovertebral joints in the cervical spine, sacroiliac joints resist rotational force through the pelvis as well as other motion segments (hips and shoulders) that have been demonstrated to refer pain to the spine. The joint that allows skull motion in combination with the first vertebrae, the dens, and the second vertebrae is different from other spine joints and results in a complex set of head movements in relation to the rest of the body. Despite the focus since the 1960s on discogenic pain, these diarthrodial joints are commonly associated with pain. The following section discusses the role of injection procedures in diagnosing and treating pain syndromes involving the various spine joints.
Facet Joints of the Cervical, Thoracic, and Lumbar Spine
As stated previously, the facet joints are paired diarthrodial joints, on the posterior aspect of the vertebral bodies, but they have slightly different forms and functions in each of the five sections of the spine. Occipitocervical, cervical, thoracic, lumbar, and sacral joints each have different orientations, forms, and functions. What they all share is the functional contribution to proprioception, balance, and stability—the three key components to ensuring accommodation of a narrow neutral zone in the three-joint complex model of the vertebral motion segment. These joints are still considered as the main source of axial pain. As early as 1911, Goldthwait postulated that the facet joints or specifically the zygapophysial joints (z joints) of the lumbar spine could be a potential pain generator of the spine. Mooney and colleagues and Hirsch and associates identified the zygapophysial joint as a source of pseudo-radicular pain in both a control hypertonic saline group and in study patients.
Epidemiologic studies note that facet-mediated pain may account for between 4% and 45% of chronic spine pain. The large variance in these statistics may be due to study inclusion criteria and the lack of adherence to exacting standards. Although positive predictive value for clearly delineating facet joint-mediated pain from generalized low back pain continues to generate vigorous debate, the ubiquity of facet joint arthropathy is undeniable. Cadaveric studies have shown facet joint arthropathy to be present in 100% of cadaveric spines over 60 year old. Although clues may be obtained by correlating history, physical examination findings, and imaging, no pathognomonic test/maneuver exists to diagnose facet-mediated pain. Facet joint pain is currently diagnosed by a preponderance of evidence. The lack of any test with high positive prognostic value is likely due to known compensatory mechanisms that are associated with joint pain/inflammation like muscle spasm, altered movement mechanics, and pain referral patterns. The nerve supply to facet joints is robust and capable of causing pain similar to that resulting from overuse injury of peripheral joints elsewhere in the body. Articular joints possess a known pattern of disease/injury and their pain can be ameliorated using well-described diagnostic techniques with acceptable reliability and validity.
Unfortunately, there is no gold standard criterion to confirm with high positive predictive value the presence of facet-mediated pain. The accepted standard combines clinical judgment with a diagnostic or therapeutic facet joint injection with glucocorticoids. Though prone to operator error, multiple studies demonstrate that erudite use of facet joint injections can serve dual diagnostic and therapeutic goals in returning patients to function. There are currently two techniques employed to block pain from facet joints: intra-articular injection of the facet joint capsule and blocking the medial branch nerves transmitting pain signals from the joint to the spinal cord/brain. Neither of these procedures should be considered as a stand-alone procedure but should be combined with aggressive rehabilitation to ameliorate that above described disabling compensatory mechanism of spasm, atrophy, stiffness, and splinting.
Mitigation of pain with a single facet joint injection was the early standard for the diagnosis of facet joint. However, this methodology produced an unacceptably high false-positive rate of up to 38%. It has therefore been advocated that a reliable control be employed in the form of the so-called double-block protocol. The double-block protocol is performed utilizing anesthetics of varying durations of effect on subsequent injections and having the patient maintain two accurate postinjection pain diaries. If the duration of pain relief is concordant with the half-life of the diagnostic anesthetic, then the injection is considered diagnostic for facet pain. In addition, many of the best-performed postoperative studies advocate the use of a cutoff score 75%, 80%, or even 100% pain relief to indicate a positive response, as opposed to the earlier practices of 50% pain relief ( Fig. 107-4 ). Furthermore, the importance of outcome measures cannot be stressed enough. Evaluation of patients with validated functional measures like the Patient Disability Questionnaire (PDQ), PROMIS-Suite, Pain Disability Index (PDI), Euro-Qual, SF-18, NDI, or even the “old standard” Oswestry should be utilized when interpreting the effectiveness of facet treatments (and really any of the interventional procedures discussed in this chapter).
Related posts:
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Ventral and Ventrolateral Subaxial Decompression
Diffuse Idiopathic Skeletal Hyperostosis
Timing of Surgery Following Spinal Cord Injury
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