This copy is for personal use only. To order printed copies, contact [email protected] Reviews and Commentary Spinal Injections for Pain Management1 Image-guided spinal injection is commonly performed in symptomatic patients to decrease pain severity, confirm the pain generator, and delay or avoid surgery. This article focuses on the radiologist as spine interventionist and addresses the following four topics relevant to the radiologist who performs corticosteroid injections for pain management: (a) the rationale behind corticosteroid injection, (b) the interaction with patients, (c) the role of imaging in procedural selection and planning, and (d) the pearls and pitfalls of fluoroscopically guided injections. Factors that contribute to the success of a pain management service include communication skills and risk mitigation. A critical factor is the correlation of clinical symptoms with magnetic resonance (MR) imaging findings. Radiologists can leverage their training in MR image interpretation to distinguish active pain generators in the spine from incidental abnormalities. Knowledge of fluoroscopic anatomy and patterns of contrast material flow guide the planning and execution of safe and effective needle placement. q RSNA, 2016 Online supplemental material is available for this article. 1 From the Department of Musculoskeletal Radiology, Massachusetts General Hospital, 55 Fruit St, YAW 6030, Boston, MA 02114. Received September 17, 2015; revision requested October 23; revision received January 26, 2016; accepted February 19; final version accepted March 30. Address correspondence to the author (e-mail: [email protected]). q RSNA, 2016 Radiology: Volume 281: Number 3—December 2016 n radiology.rsna.org 669 n How I Do It William E. Palmer, MD HOW I DO IT: Spinal Injections for Pain Management I n 1930, epidural anesthetic injection was described in the treatment of sciatica (1). Epidural steroid injection (ESI) was first performed in the 1950s, it evolved as a therapeutic option during the 1960s, and it became a cornerstone in the management of low back pain and sciatica in the 1970s (2–6). During these decades, needle placement and injection site depended on palpated landmarks and loss-of-resistance techniques. In the 1980s and 1990s, radiologists and Essentials nn Structured interactions during history taking, intervention, and discharge build patient-physician relationships that promote trust and create rewarding opportunities for radiologists to counsel patients and affect clinical decision making. nn Correlation of symptoms and imaging findings guides targeted inspection of MR images, differentiation of active pain generators in the spine from painless structural abnormalities, and formulation of a treatment strategy. nn Radiologists can leverage their training in MR image interpretation, their knowledge of fluoroscopic anatomy, and their experience with contrast material administration to plan and execute safe and effective needle placement. nn Therapeutic outcomes depend on four factors: symptoms correlate with MR imaging findings, symptoms result from inflammation, inflammation is reversible, and corticosteroid reaches the inflamed tissue. nn Corticosteroid injection has been performed for decades for pain management; however, it is considered an off-label use in spine intervention in the United States because the Federal Drug Administration has not approved corticosteroids for epidural or epiradicular administration. 670 Palmer anesthesiologists began to use fluoroscopy to determine the accuracy of caudal and interlaminar needle placement, and they used epidurography to understand patterns of injectate flow. They found needle misplacements in 25%–38% of blind procedures performed by experienced injectionists (7–9). Epidurography was necessary to confirm injectate location and to exclude intravascular or intrathecal administration (10–13). Computed tomography (CT) and magnetic resonance (MR) imaging spurred growth in intervention by revolutionizing the noninvasive diagnosis of pain generators (14,15). When spinal stenosis, disk herniation, and facet arthropathy correlated with symptoms, they were targeted for therapeutic interventions. When the correlation was uncertain, they were targeted for a systematic series of diagnostic interventions. ESIs shifted from caudal routes performed blindly to lumbar and cervical routes directed at the imaging abnormalities and presumed pain sources (16). As fluoroscopic techniques evolved, facet injection, nerve root block (NRB), and discography were added to lumbar and cervical ESIs (17). During the 1980s and 1990s, utilization data showed dramatic volume growth as spinal interventions gained widespread acceptance (18,19). Lumbar ESI rates for spinal stenosis increased 300% within 2 decades (from 1994 to 2011) (20–23). By 2010, more than 2.2 million lumbar ESIs were performed yearly in Medicare patients (21). Facet injections surged 147% from 1993 to 1999 and increased another 300% from 1998 to 2006 (23– 26). Medicare payments for spinal injections expanded 629% from 1994 to 2001 (23). Before 2000, anesthesiologists performed the majority of injections (26). By 2007, procedures were performed by anesthesiologists (49%), physiatrists (25%), family practitioners (12%), orthopedists (6%), and radiologists (3%) (27). Within the pain management domain, a small percentage of providers performed a disproportionately high percentage of spinal interventions (22,23,26,27). Overuse led to the scrutiny of therapeutic outcomes and the publication of contradictory articles that defended or criticized injections depending on the interests of the authors (16,26,28– 38). Epidemiologists tended to focus on long-term outcomes and surgical end points. Injectionists focused on short-term outcomes, accepting the fact that interventions could modulate but not cure the underlying cause of symptoms. Research studies remain difficult to compare due to disparate symptoms (back pain vs radiculopathy), diagnoses (spinal stenosis vs disk herniation), injection types (interlaminar vs transforaminal), procedural techniques (blind injection vs fluoroscopic guidance), patient demographics, pharmaceutical agents, and drug doses (7,30,32–34,39–41). Corticosteroid Properties Corticosteroids are powerful anti-inflammatory medications. The rationale for administration is the suppression of inflammation implicated in the pathogenesis of radiculopathy and axial pain (42). Inflammation as a generic physiologic response can be triggered by numerous stimuli. In disk herniation and spondylosis, radiculopathy results from both chemical and mechanical irritants (43–45). Phospholipase A2 and other enzymes are released into the epidural space by disk material and annular tear. These inflammatory mediators recruit macrophages that secrete cytokines and catalyze the inflammatory cascade; they produce prostaglandins and leukotrienes that sustain the inflammatory cycle (46). Mechanical nerve root stretching, tethering, and compression provoke Published online 10.1148/radiol.2016152055 Content codes: Radiology 2016; 281:669–688 Abbreviations: ESI = epidural steroid injection FDA = Food and Drug Administration NRB = nerve root block Conflicts of interest are listed at the end of this article. radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management the same inflammatory reaction due to cellular damage and ischemic injury (47). Corticosteroids inhibit the release of cytokines and the synthesis of prostaglandins, thereby suppressing the physiologic response (42,48). Injectable corticosteroids are nonparticulate or particulate. Nonparticulate corticosteroids have rapid-onset but short-lived anti-inflammatory effects, whereas particulate corticosteroids have delayed but sustained effects. Nonparticulate preparations, including dexamethasone sodium phosphate and betamethasone sodium phosphate, are fully soluble and clear in appearance. Particulate suspensions contain corticosteroid esters that are insoluble in saline, local anesthetic, and iodinated contrast material (49). Particulate corticosteroids, including methylprednisolone acetate, triamcinolone acetonide, and betamethasone acetate, create a white cloudy mixture when agitated. Methylprednisolone has the largest particles, whereas betamethasone has the smallest (49–51). Particulate corticosteroids have been associated with neurologic damage during transforaminal cervical and lumbar injections (51–54). Because of limited data, the incidence of these rare complications cannot be determined (55). The proposed mechanism is direct intra-arterial administration resulting in embolic occlusion followed immediately by ischemia or infarction of neural tissue (Figs 1, 2). Neurologic sequelae, including quadriplegia, paraplegia, and death, are extremely rare but catastrophic complications, causing some authors to advocate use of a nonparticulate corticosteroid in all transforaminal procedures (50,56,57). No neurologic complications due to nonparticulate corticosteroid use have been reported (58). In April 2014, the Food and Drug Administration (FDA) posted a safety announcement requiring manufacturers to add a warning in package inserts about adverse neurologic events (59). In that same posting, the FDA stated: “Injecting corticosteroids into the epidural space of the spine has Radiology: Volume 281: Number 3—December 2016 n Palmer Figure 1 Figure 1: Schematic drawing of the prone lumbar spine shows lumbar structures, needle placements, and cross-sectional relationships of structures in the spinal canal and foramina. Radicular arteries may be paired, unilateral, or absent. In lumbar NRB, the needle targets the epiradicular space that surrounds the ventral ramus of the spinal nerve, the dorsal root ganglion (∗), and the nerve roots. In ESI, the needle targets the small triangle of fat in the dorsal epidural space. In lumbar facet injection (F1), needle trajectory must account for joint curvature. Otherwise, joint access is blocked by margins of articulating processes (F2). been a widespread practice for many decades; however, the effectiveness and safety of the drugs for this use have not been established, and FDA has not approved corticosteroids for such use.” Several professional societies responded to this FDA safety announcement, expressing concern that the FDA warning did “not differentiate between the risks and benefits of transforaminal versus interlaminar routes of administration, and particulate versus non-particulate formulations of steroids” (60). Numerous factors influence the choice of injected corticosteroid, including FDA warnings, published articles, recommendations from specialty societies, and package inserts. Data from these varied sources may be contradictory, requiring judgments on safety and efficacy based on personal experience, the regulatory environment, and the availability of drugs in the hospital formulary. radiology.rsna.org Interaction with Patients Structured interactions promote trust and build patient-physician relationships that can last for years in individuals who suffer from chronic neck or back pain and who return for periodic injections. In my practice, these interactions are important because patients relay their positive and negative experiences to referring physicians. These interactions also create rewarding opportunities for radiologists to counsel patients and affect clinical decision making. Patients actively seek the perspective of nonsurgeons. Radiologists should understand the treatment options and lifestyle modifications that help patients stay active. During procedural visits, I engage patients at four junctures to obtain or convey information. These purposeful interactions can be categorized as the interview, the blow-by-blow, the teachable moment, and the discharge. The 671 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 2 Figure 2: Cervical structures and needle placement for NRB. (a) Schematic drawing of the supine cervical spine depicts cross-sectional relationships of structures in the spinal canal and foramina. Radicular and segmental medullary arteries are too small to identify with MR imaging. In cervical NRB, needle placement is posterior to great vessels and nerve plexus. The needle targets the foramen posteriorly and inferiorly in close proximity to the exiting nerve and dorsal root ganglion (∗). AS = anterior scalene muscle, CA = carotid artery, JV = jugular vein, MS = middle scalene muscle. (b) CT angiographic image at C5–6 disk level shows posterior location of the jugular vein (JV). A graphically depicted needle (NRB) is overlaid at 45° and shows superimposition on the external jugular vein (EJ). To shift the great vessels from the needle path during cervical NRB, turn the head away from the symptomatic side. Lateral approach may be necessary when MR imaging reveals great vessels in a posterior location. Enhancing vessels (arrows) surround nerve root ganglia (∗) in foramina. CA = carotid artery, VA = vertebral artery. first interaction, the interview, focuses on clinical history and incorporates the consent process. The second and third interactions, the blow-by-blow and the teachable moment, respectively, take 672 place during and immediately after the intervention while the patient lies on the fluoroscopy table. The final interaction, the discharge, occurs once the patient is dressed and is waiting to leave. The Interview The patient interview is critical in procedural selection and planning. I have four goals: (a) obtain a focused clinical history, (b) correlate symptoms with imaging findings, (c) approve the requested procedure or propose a different one, and (d) obtain written informed consent. In new patients, these goals often can be accomplished within 10 minutes. In returning patients, less time is required because usually little has changed and previously successful procedures can be repeated. It only takes a few questions to determine the outcome of the prior injection and reestablish the pain generator. During history taking, one should focus on spine-related symptoms. Systematic questioning (Fig 3) quickly yields enough clinical information to guide the targeted inspection of imaging studies and the formulation of a treatment plan (correlation of symptoms and imaging findings is addressed in the next section). Begin with the discrimination of axial pain from radiculopathy. When leg and back pain coexist, ask which one is predominant. Most patients would be willing to live radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management Palmer symptom-imaging correlation), and procedural selection. Explain the procedure, and educate the patient about risks. It may be necessary to disclose that the FDA has not approved corticosteroids for epidural administration. Besides fulfilling ethical and regulatory requirements, the consent process should uncover clinical conditions, medications, and allergies that increase risk and compromise outcome. The major issues are anticoagulation therapy, active infection, and contrast material reaction. When you are describing bleeding and infection risks, ask about anticoagulant and antibiotic treatments. Inquire about latex allergy, diabetes, and other recent steroid injections. In my practice, our administrative assistant screens patients prior to the procedure to avoid the discovery of unresolvable issues, such as anticoagulation therapy, in the fluoroscopy suite. Figure 3 Figure 3: Flowchart shows interview questions to be asked during history taking. A = answer, Q = question. with the lesser pain if the major pain could be relieved. Radicular symptoms often enable one to verify the pain generator during imaging correlation. In contrast, nonspecific axial pain poses diagnostic challenges. It can be acute or chronic, mild or severe, intermittent or constant, dull or sharp, localized or migratory, or any Radiology: Volume 281: Number 3—December 2016 n combination thereof. Patients often point to a general region in the neck or low back. Clinical history and physical examination have limited value in determining the cause of axial pain and guiding procedural selection (61). Informed consent follows history taking, correlation of symptoms with imaging findings (hereafter, radiology.rsna.org The Blow-by-Blow Occasionally, patients refuse to receive information during the procedure. As a coping strategy, they wear headphones to listen to music, or they prefer silence, choosing to mentally transport themselves to another place. However, most patients want to know what is happening and value a blow-by-blow narrative. The blow-by-blow serves several purposes. Patients feel connected and informed. It relieves anxiety and eliminates the element of surprise. It conveys forward progress. Verbal communication also engages the technologist, fellow, and any other individuals involved in the procedure. My custom is to announce when I am deciding where to insert the needle, putting a dot on the skin with a marker, cleaning the skin, preparing the medications, numbing the skin, positioning the needle, and injecting dye to make sure the needle is in the right place. I express my satisfaction with needle placement before I inject the steroid solution. During injection, I warn patients that the injection could cause pressure or pain. When concordant symptoms are produced, I reassure patients and state that the needle is correctly placed. Patients appreciate knowing that the procedure is going as expected. 673 HOW I DO IT: Spinal Injections for Pain Management The Teachable Moment The teachable moment begins immediately after needle removal while washing off the skin antiseptic. To set positive expectations, state that the goal of the procedure was achieved (ie, the steroid was delivered to the intended target). Indicate the rationale for injecting the steroid. Explain that the steroid works by decreasing inflammation, not by shrinking the disk herniation, reversing arthritis, or opening stenotic spinal canals. Patients should understand that the drug is a powerful anti-inflammatory agent but that the degree of pain relief depends on whether inflammation is causing the symptoms. In patients who might benefit from seeing the fluoroscopic images, reinforce the technical success of the procedure by pointing out needle placement and contrast material flow on the monitor. The Discharge The discharge process generates information about immediate pain response. Symptoms might be decreased, unchanged, or increased depending on the level of preprocedural pain and the volume of injected anesthetic. Prompt pain relief creates a positive attitude about the procedure and promotes the placebo effect. A surprising number of patients claim pain reduction even if no local anesthetic was injected. In dictated reports, record the postprocedural pain response (eg, right leg pain decreased from a score of 8 of 10 to a score of 2 of 10). If symptoms are already improved at the time of discharge, I continue to set positive expectations by explaining to the patient that the steroid was mixed with anesthetic and, therefore, it is in the same correct location. One must explain the time frame for steroid effectiveness and provide activity guidelines. Patients can become disappointed the day after injection if their pain remains unchanged. Because particles release the steroid gradually, it may take 12–24 hours for the drug to take effect, 4–6 days for its effects to become more pronounced, and more than a week for it to reach full effectiveness. Advise patients to limit 674 Palmer themselves to baseline levels of exercise and physical therapy for 4–6 days. Patients whose condition improves after 2–3 days are tempted to overdo it before the drug has reached full effectiveness, thereby stirring up inflammation that overwhelms the steroid and diminishes the overall treatment benefit. Patients often ask how long the injection will help. The time course is surprisingly predictable in patients with chronic conditions, such as spinal stenosis and facet arthropathy. Symptoms decrease during the first 2–3 weeks after injection when the anti-inflammatory effects are strongest but return to baseline levels over the following 6–8 weeks as the particulate steroid dissipates. In patients with acute conditions, such as disk herniation and annular tear, the steroid can break the inflammatory cycle and relieve pain for more than 6–8 weeks. When new symptoms are superimposed on long-standing ones, such as acute radiculopathy superimposed on chronic low back pain, explain that corticosteroid injection may accelerate a return to the baseline condition. Steroid administration decreases the new reversible nocioceptive pain but leaves the long-standing irreversible neuropathic pain unchanged. Role of Imaging in Procedural Selection Symptom-imaging correlation guides procedural selection and planning (Movie 1 [online]). It enables one to verify the appropriateness of the requested intervention or justify modification. Procedural modification is most practical when the radiologist has authorization to proceed independently. For the radiologist who possesses the skill, experience, and confidence to assume responsibility for treatment decisions and, therefore, therapeutic outcomes, the role in pain management expands beyond rote injection. Imaging results are available in the majority of cases. During screening, our administrative assistant asks patients to bring their MR images if they were obtained at a different institution. On rare occasions, we proceed without the benefit of symptom-imaging correlation. Procedural selection begins with a judgment on the pain generator. The following symptom-imaging correlation exercise is popular with our fellows because it hones skills in both history taking and MR image interpretation. The exercise has two variations. In one variation, we interview the patient before we review the MR images. We then deduce the most likely pain generator and predict the MR imaging findings. In the other variation, we review the MR images before we interview the patient, then we deduce the most likely pain generator and predict the patient’s symptoms. Symptom-imaging correlations are often obvious, but surprising mismatches do occur. These mismatches teach valuable nuances in pain management and MR image interpretation. In younger patients with acute or subacute radiculopathy, dermatomal information serves to focus MR image review. Symptoms usually correlate perfectly with nerve entrapment because of lateralization of single-level disk abnormalities. Occasionally, a symptomspecific search will lead to the diagnosis of an intraforaminal or lateral disk extrusion that explains symptoms but that was overlooked at the time of MR image interpretation (Fig 4). Transforaminal NRB targets the pain generator and delivers the steroid directly to the inflamed nerve root (62–64) (Figs 5, 6). In older patients with chronic unilateral radiculopathy, symptom-imaging correlation is more challenging because of multilevel spondylosis. Therapeutic success is also more challenging when severe stenosis causes irreversible nerve damage and neuropathic pain. Transforaminal NRB remains a recommended treatment option if dermatomal information reveals a specific pain generator. One exception is nerve compression by a facet cyst. To address this problem, one can combine percutaneous cyst rupture with intra-articular corticosteroid injection (65) (Fig 7). In older patients with chronic bilateral radiculopathy, the radiologist should solicit signs of neurogenic claudication. Intermittent back pain is precipitated by prolonged standing or radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 4 Figure 5 Figure 4: Intraforaminal disk extrusion missed at prospective interpretation in a 41-year-old woman with acute L4 radiculopathy. Axial T2-weighted MR image shows unsuspected L4–5 intraforaminal disk extrusion (white arrowhead) causing mechanical impingement on left L4 nerve root ganglion (arrow). During NRB (not shown), the needle targeted the L4 ventral ramus peripheral to the foramen to avoid severe pain production due to foraminal stenosis and nerve root displacement. Right L4 nerve root ganglion (black arrowhead) is in its normal location and is surrounded by fat. walking and is relieved by sitting or leaning forward. One should expect MR imaging to reveal spinal stenosis, which is the leading reason for spinal surgery (18). When MR imaging shows multilevel stenosis, dermatomal information may indicate the level of pain generator. Interlaminar ESI is the recommended procedure because the corticosteroid can spread cranially and caudally over multiple disk levels. When symptoms suggest lumbar facet syndrome (posterior ramus syndrome), one must scrutinize the zygapophyseal joints for signs of inflammation, including effusion, capsulitis, and periarticular edema. Back pain may radiate into the buttocks, groin, or posterior thigh and may worsen with prolonged standing and extension and rotation or lateral bending movements (71). Sclerotomal maps for posterior rami depict the patterns of referred pain from facet joints but are less accurate than dermatomal maps for patterns of referred pain from ventral rami (72). Clinical history and physical examination findings cannot be used to Radiology: Volume 281: Number 3—December 2016 n predict treatment responses to facet injections (73). If corticosteroid administration alleviates symptoms, systematic anesthetic injections (medial branch blocks) yield corroborative diagnostic information prior to radiofrequency ablation. Segmental instability creates multiple pain generators and causes debilitating symptoms that respond poorly to injections. Initially, when back pain predominates, symptoms may respond to ESI, facet injections, or a combination thereof. Progressive facet degeneration leads to articular hypermobility, attritional bone loss, and malalignment. Increasing anterolisthesis exacerbates spinal stenosis and foraminal nerve impingement. When neurogenic claudication and radiculopathy become superimposed on back pain, segmental instability often forces surgical intervention and spinal fusion. In patients with chronic nonlocalizing low back pain, one must inspect disks and facets to judge the relative importance of discogenic and arthropathic abnormalities. The basic radiology.rsna.org Figure 5: Lumbar NRB in a 64-year-old man with right leg pain correlating with L4–5 lateral recess stenosis and right L5 mechanical impingement. Anteroposterior fluoroscopic image in the prone position shows the needle (arrow) in supraneural location between L5 and S1 pedicles (∗). Contrast material (arrowheads) flows cranially into the spinal canal along the L5 epiradicular space to the level of the L4–5 disk space and pain generator in lateral recess. procedural alternatives are ESI and facet injection. These limited choices seem trivial enough, but decision making can be problematic due to overlapping clinical syndromes and equivocal MR imaging findings (66–68). Incidental MR imaging abnormalities in asymptomatic adults are difficult to discriminate from true pain sources in symptomatic patients (15,61,69,70). The default intervention is ESI. In the absence of MR imaging findings that support a different level of injection, the radiologist should select the L4–5 level because injectate typically flows cranially and caudally, and it will cover the three lowest movable disk spaces. One should inspect MR images for bone marrow edema involving facets, pars defects, spinous processes (Baastrup syndrome), and lumbosacral pseudoarthroses (Bertolotti syndrome). When symptoms are highly localized, ask the patient to point to the most painful spot and document that site fluoroscopically, including the pointing 675 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 6 Figure 6: Cervical NRB in 41-year-old woman with left arm pain correlating with C6–7 disk extrusion and left C7 mechanical impingement. (a) Oblique fluoroscopic image obtained in the supine position shows foramina (curved lines) are opened by lateral rotation of the detector approximately 45°. During set-up, turn the head away from the side of needle placement, thereby displacing the great vessels and nerve plexus from the needle path. The needle tip (arrow) is directed inferiorly toward C6–7 foramen to target exiting left C7 nerve and posteriorly to avoid vertebral artery. The needle hub has been preloaded with contrast material (arrowhead) to obviate gas injection. (b) Digital subtraction posteroanterior fluoroscopic image shows contrast material (arrowheads) flowing along the epiradicular space into the foramen between C6 and C7 pedicles (∗). Subtraction technique may improve detection of intravascular contrast material. The needle (arrow) is barely visible. (c) Subsequent posteroanterior fluoroscopic image shows contrast material (arrowheads) spreading along C7 nerve between pedicles (∗) into the epidural space. The needle (arrow) terminates at the border of lateral masses. It can be advanced into outer foraminal thirds if contrast material flow is unsatisfactory (intravascular or extraforaminal). Figure 7 Figure 7: Facet cyst rupture in 71-year-old man with left L5 radiculopathy correlating with left L5-S1 foraminal cyst. (a) Axial T2-weighted MR image at L5-S1 level shows foraminal cyst (straight arrow) is contiguous with degenerated left L5-S1 facet joint (curved arrow) and proximate to left L5 nerve (arrowhead). (b) Anteroposterior fluoroscopic image in the prone position shows contrast material in the needle hub (straight arrow) and facet cyst (curved arrow). The inferior recess of the left L5-S1 facet joint was accessed with anteroposterior fluoroscopy by moving the needle caudally off the articulating process. (c) Subsequent anteroposterior fluoroscopic image shows epidural flow of contrast material (arrowheads), indicating cyst rupture. Contrast material no longer fills the cyst or needle hub (arrow). Corticosteroid may prevent or delay recurrence of facet cyst. finger. If this site corresponds to bone marrow edema or another potential pain generator on MR images, it can be targeted for diagnostic information and therapeutic response. 676 Pearls and Pitfalls of Fluoroscopyguided Injections The following pearls and pitfalls focus on fluoroscopy-guided injections (Movie 2 [online]). Expert interventionalists develop individualized techniques and often approach the same problems and procedures in different ways. Some physicians prefer to use computed radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management tomography (CT) to guide needle placement (74–80). This preference reflects training experience, resource availability, and institutional policy. No studies have compared the effectiveness or safety of CT-guided interventions versus fluoroscopy-guided interventions. Neurologic complications have occurred during spine injections performed with both modalities (81–84). Advantages of CT include higher reimbursement and cross-sectional documentation of needle position. CT may improve the accuracy and safety of needle placement when overlapping bones make it difficult to plan an unobstructed needle trajectory during fluoroscopic set-up and when intervening soft-tissue structures must be avoided but cannot be seen fluoroscopically. In thoracic NRB, for example, CT shows the complex relationship between the ribs, transverse processes, and lung. For atlantoaxial (C1–2) facet injection, CT helps to avert complications from arterial puncture by depicting the vertebral artery (82). In lumbar facet injection, when intraarticular placement is essential for diagnostic information or therapeutic cyst rupture, CT shows marginal osteophytes and hairline joint spaces (85). Disadvantages of CT include higher cost, increased radiation dose, longer procedural time, and lack of availability. The radiation dose of CT interventions can be decreased to the level of fluoroscopic interventions by using a low-dose protocol that eliminates acquisition of a topogram, minimizes both energy and tube current, and severely restricts the number of image acquisitions during needle placement (86–88). At institutions where interventional CT is a limited resource, CT-guided injections for pain management can be challenging to schedule if they must compete for scanner time with biopsy, oncologic ablation, and abscess drainage procedures. An advantage of fluoroscopy is the live real-time observation of contrast material flow and, therefore, vessel opacification in the case of inadvertent intravascular needle placement. During CT-guided procedures, because Radiology: Volume 281: Number 3—December 2016 n Palmer conventional scanning is delayed until operators leave the room, intravascular contrast material washes away, thereby precluding vessel identification. Intermittent fluoroscopy, if performed before and after but not during contrast material injection, also fails to show opacified vessels (52,89). In mixed injections with concurrent intra- and extravascular contrast material flow, only the extravascular contrast material remains visible, creating the false reassurance of extravascular needle placement. Some authors have proposed the use of CTfluoroscopic techniques to improve the real-time detection of opacified vessels (90–92). However, vessels outside of the limited stack of CT images remain impossible to identify. A potential advantage of fluoroscopy is the range of detector rotation, which enables steep craniocaudal angulation. Steeper craniocaudal angles are often required in L5 and S1 NRBs, as well as in lumbar ESIs, in the setting of interlaminar collapse or exaggerated lumbar lordosis. The advantages of both modalities can be attained with one unit that combines C-arm fluoroscopy with cone-beam CT (93,94). The flat-panel detector spins and acquires a volumetric data set enabling multiplanar two-dimensional reformations and three-dimensional reconstructions. Because the fluoroscopic image is overlaid onto the three-dimensional data set, the unit can align itself according to selected skin entry and target locations for bull’s-eye needle navigation. If necessary, final needle position and contrast material location are documented with a second volumetric acquisition. Risk and Risk Mitigation Adverse events are exceedingly rare when experienced practitioners use fluoroscopic guidance and inject contrast material to confirm needle position (16). In more than 8000 cervical, thoracic, and lumbar interventions performed by me or under my supervision, none have been complicated by hemorrhage, infection, or neurologic damage. Radiologists should recognize and radiology.rsna.org manage immediate and delayed complications or perform patient triage for appropriate care. Adverse events can occur during injection (pain, hemorrhage, reaction to contrast material, vasovagal reaction, dural puncture, nerve or vessel damage), immediately after injection (pain, hemorrhage, extremity weakness, paresthesia), or days later (infection, headache, flushing reaction to steroid). Most adverse events can be avoided by anticipating risks discovered during history taking and image review. Bleeding risk increases with age, underlying coagulopathy, severity of spondylopathy, and difficulty of needle placement (95). Although the incidence is unknown, bleeding risk increases in patients who have undergone anticoagulation therapy, and it increases substantially in patients taking multiple anticoagulant and antiplatelet medications, including nonsteroidal anti-inflammatory drugs (95). Epidural hematoma rarely occurs; however, it poses the greatest threat because of spinal cord or cauda equina compression, and it requires surgical evacuation to prevent permanent neurologic sequelae. Incidence has been estimated at 1:220 000 after subarachnoid anesthesia and at 1:150 000 after epidural anesthesia in healthy patients (96). Epidural hematoma has been described after ESI and facet injection in patients without coagulopathy or anticoagulation therapy (96). Patients should discontinue use of anticoagulants for appropriate intervals, and they should coordinate bridging therapy according to instructions from referring physicians or consulting cardiologists (97). ESI is considered safe in patients taking nonsteroidal anti-inflammatory drugs (98). In a study of 1214 patients who underwent ESI, no hemorrhagic complications occurred in 383 (32%) patients taking nonsteroidal anti-inflammatory drugs (98). Iodinated contrast material should be approved for myelography in case of inadvertent intrathecal administration. One should recognize patterns of layering subarachnoid contrast to avoid saddle anesthesia and ascending paralysis from anesthetics and arachnoiditis from corticosteroids. Nearly 3% of scheduled 677 HOW I DO IT: Spinal Injections for Pain Management Figure 8 Figure 8: Intravenous injection during interlaminar ESI in a 48-year-old woman with axial low back pain after L4–5 anterior fusion. Lateral fluoroscopic image obtained during contrast material injection shows needle tip (arrow) projecting over the spinal canal at L3–4 disk level. Extensive epidural venous network (arrowheads) is visible from L2 to L5. Needle repositioning could not evade vessels. Thus, ESI was performed at L2–3 (images not shown). ∗ = L4–5 interbody cage. patients have had known or suspected reactions to contrast material (16). In these patients, options include (a) premedication with oral prednisone and diphenhydramine, (b) steroid injection without contrast material confirmation of needle location, and (c) injection of a gadolinium-based contrast agent. Gadolinium chelates provide off-label alternatives to iodinated contrast material and appear safe for use in epidural injection (99). Intrathecal administration should be carefully avoided. Digital subtraction fluoroscopy may improve visualization of gadolinium-based contrast material, which is less radiopaque than iodinated contrast material. Extensive arterial and venous networks crisscross the epidural and epiradicular spaces of the spinal canal and neural foramina (Figs 1, 2, 8). Overall, 678 Palmer intravenous needle placements are more common in patients with cervical NRBs (incidence range, 19.4%–32.8%) than in those with lumbar NRBs (incidence range, 11.2%–13.1%), but actual incidence depends on injection level (10–13). In the cervical spine, vascular cannulation is more likely from C3–4 to C5–6 (range, 40%–57%) (13). In the lumbosacral spine, it is more than twice as likely at S1 (21.3% incidence) compared to lumbar levels (8.1% incidence) (10–12). In both the cervical spine and the lumbar spine, aspiration fails to produce a flashback of blood in 45%–73% of intravenous needle placements subsequently proved via contrast material opacification (10,100). Simultaneous intra- and extravascular contrast material flow (mixed injection) is observed more commonly than is intravascular flow alone in both cervical NRBs and lumbar NRBs (12,13). In the cervical spine, mixed injection was reported in 18.9% of injections as compared with vascular flow alone, which was reported in 13.9% of injections (13). Concurrent flow creates challenges because extravascular contrast material can obscure vessels. To best detect vessels, one should optimize fluoroscopic techniques by decreasing the field of view, dimming the lights, using digital subtraction angiography, and injecting contrast agents that contain a higher concentration of organic iodine (eg, 300 mg/mL). Injected steroids have systemic glucocorticoid effects in addition to local anti-inflammatory effects. Fortuitous benefits include temporarily decreased pain from arthritis and spondyloarthropathy. Undesired consequences include elevation of the blood glucose level, suppression of the immune system, and suppression of the hypothalamic-pituitary axis. One should caution patients with diabetes to monitor their blood glucose levels for 7–10 days after the procedure. Ask patients about antibiotics they are taking, and reschedule patients who are taking antibiotics for active infections. Prophylactic antibiotics are not a contraindication. Repeated steroid injections at short intervals (less than 8 weeks for particulate preparations) can inhibit recovery of the hypothalamic-pituitary axis and can lead to decreased bone mineral density (101–103). Cushingoid symptoms, although rare, can persist for several months after steroid injections have been terminated (28,104). Injectate composition and volume depend on numerous factors and vary widely between practitioners (Table). Choice of corticosteroid should take into account the risk of intravascular or intrathecal injection and, therefore, particle size and the addition of preservatives (benzyl alchohol) or vehicles (polyethylene glycol) (105,106). Corticosteroid particles may aggregate and form larger particles when mixed with local anesthetics and contrast agents containing certain preservatives (49,50). Commonly used anesthetics include lidocaine, bupivacaine, and ropivacaine. Formulations with preservatives (methylparaben) and vasoconstrictors (epinephrine) should be avoided. Methylparaben is classified as an antimicrobial preservative, and it is added for its bacteriostatic activity. Choice of anesthetic should take into account patient health, pain severity, and postdischarge activities. Use anesthetics with caution in elderly or unsteady patients and in individuals who are planning to drive or take public transportation immediately after they are discharged. Patients with baseline weakness or paresthesia are more susceptible to anesthetic effects and may develop profound postprocedural weakness, even if only a small volume of anesthetic is administered. Procedural Tips and Techniques In the majority of spine procedures, patients are placed in the prone position. This position can exaggerate lumbar lordosis, aggravate nerve root entrapment, and provoke facet-related pain. Patient comfort is more important than perfect prone positioning, as the goal is to limit progressive discomfort and involuntary movement. Placement of a pillow under the pelvis can help to reduce lordosis and can relieve symptoms. Patients who cannot lie in the prone position may be able to tolerate radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management Palmer Drug Doses in Common Therapeutic Spinal Injections Injection Type Dose Lumbar ESI MGH protocol* Published protocol† Corticosteroid dose Anesthetic dose Saline volume Thoracolumbar transforaminal nerve root injection MGH protocol at or above conus MGH protocol below conus‡ Published protocols Corticosteroid dose Anesthetic dose Cervical transforaminal nerve root injection MGH protocol Published protocols Corticosteroid dose Anesthetic dose Lumbar or cervical facet injection MGH protocol Published protocols Corticosteroid dose Anesthetic dose BTM 15 mg (2.5 mL) followed by saline (2–4 mL) mixed with lidocaine 1% 0–10 mg (0–1 mL) MPA 40–120 mg (1–3 mL), TCA 60–120 mg (1.5–3 mL), BTM 9–18 mg (1.5–3 mL) Bupivacaine 0.25%–0.5% 15–40 mg (3–8 mL), lidocaine 0.5%–1.0% 15–40 mg (3–8 mL) Saline 0–8 mL DSP 8–12 mg (2–3 mL) BTM 6–15 mg (1–2.5 mL) mixed with saline 1–2.5 mL & lidocaine 1% 0–10 mg (0–1 mL) MPA 20–80 mg (0.5–2.0 mL), TCA 20–40 mg (0.5–1.0 mL), BTM 6–9 mg (1.0–1.5 mL), DSP 4–8 mg (1–2 mL) Lidocaine 0.5%–1.0% 10–20 mg (1–4 mL), bupivacaine 0.25%–0.5% 5–20 mg (1–8 mL) DSP 8–12 mg (2–3 mL) DSP 4–12 mg (1–3 mL), BTM 6 mg (1 mL), TCA 40 mg (1 mL), MPA 40 mg (1 mL) Bupivacaine 0.25%–0.5% 2.5–5 mg (1 mL), lidocaine 0.5%–2.0% 5–20 mg (1 mL) TCA 40 mg (1 mL) mixed with ropivacaine 0.5% 5 mg (1 mL) or lidocaine 1% 10 mg (1 mL) TCA 20–60 mg (0.5–1.5 mL), BTM 3–6 mg (0.5–1.0 mL), MPA 20–60 mg (0.5–1.5 mL) Lidocaine 1%–2% 5–20 mg (0.5–1.0 mL) Note.—Medication and dose selections require physician discretion. BTM = betamethasone acetate, 3 mg/mL and betamethasone sodium phosphate, 3 mg/mL; DSP = dexamethasone sodium phosphate, 4 mg/mL; MPA = methylprednisolone acetate, 40 mg/mL; TCA = triamcinalone acetonide, 40 mg/mL. * Massachusetts General Hospital (MGH) protocols are routinely modified based on recommendations by specialty societies and consensus groups. † Published protocols may not reflect current recommendations by specialty societies and consensus groups. ‡ Corticosteroid dose is proportionate to epidural flow. imaging in the oblique or lateral decubitus position. Fluoroscopic set-up can neutralize the challenges posed by lordosis, scoliosis, spondylolisthesis, and oblique patient positioning. By standardizing needle trajectory, even deformed spondylotic spines can be depicted in conventional anteroposterior, lateral, and oblique views at the level of injection. Set-up usually involves four systematic maneuvers. First, one must identify the level of intervention. Second, one must rotate the detector left-right to obtain a straight anteroposterior projection of the spine. Third, one must adjust the craniocaudal tilt to normalize endplate relationships. The final maneuver involves rotating the detector left-right to obtain a bull’s-eye projection for needle navigation. Fluoroscopy units that enable one to use saved positions allow rapid transition between different views. Radiology: Volume 281: Number 3—December 2016 n One should archive fluoroscopic images to document the procedure, needle position, and contrast material distribution for billing and medicolegal purposes. Referring surgeons may review the images with patients and determine whether the steroid reached its intended target. In patients who have undergone repeated injections, the images provide templates for reproducing safe and effective needle placement. One should archive a minimum of two images. The first image, obtained before steroid delivery, shows extravascular contrast material. The second, obtained after steroid delivery, shows contrast material washout and proves that the steroid flowed into the same location as the contrast material. Lumbosacral transforaminal injection.—The rationale for transforaminal NRB is precise drug delivery to the inflamed nerve root (Figs 5, 9). The radiology.rsna.org epiradicular space, which is the target in needle placement, surrounds the ventral ramus. Because the epiradicular and epidural spaces are continuous, injectate flows selectively along the spinal nerve and nerve root into the spinal canal (Figs 5, 6). Transforaminal injection delivers the corticosteroid directly to the pain generator in the foramen or ventral epidural space. Thus, NRB can yield a superior therapeutic effect with a smaller corticosteroid dose than that used with interlaminar ESI (35,62– 64,107). In ESI, the corticosteroid takes the path of least resistance, spreading indiscriminately from the dorsal epidural space throughout the spinal canal. When the foramen is patent, intraforaminal needle placement can be supraneural (subpediculate) or infraneural (retrodiskal) (Figs 10, 11). Select the supraneural location, the so-called safe triangle, for reliable epiradicular flow of 679 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 9 Figure 9: Fluoroscopic set-up for sacral (S1) NRB in a 53-year-old man with left leg pain correlating with L5-S1 disk extrusion and left S1 mechanical impingement. (a) Anteroposterior fluoroscopic image shows the detector was tilted craniocaudally to align the inferior margin of posterior S1 foramen (thin curved line) with the superior margin of anterior S1 neural arch (arrowheads). Sacral orientation determines the degree of craniocaudal tilt. The detector was rotated laterally to align the medial margin (thick curved line) of S1 pedicle (∗) with lateral margin of posterior S1 neural foramen along expected course of S1 nerve root. Curved needle (arrow) improves foraminal navigation. Until it enters the foramen, the needle must target the inferolateral border of the posterior S1 foramen. (b) Subsequent anteroposterior fluoroscopic image shows the needle hub (white arrow) and needle tip (white arrowhead) are oriented cranially along the expected course of the S1 nerve root. Initially, contrast material flowed retrograde into the posterior S1 foramen (black arrow). After advancing the needle, contrast material (black arrowheads) spread favorably along S1 pedicle (∗) and S1 nerve root to the L5-S1 disk level. the steroid along the nerve root to the next higher disk level (64) (Fig 5). The safe triangle is bounded by the pedicle superiorly, the exiting nerve medially, and the vertebral body anteriorly (64) (Fig 10). Veins, and sometimes the radicular artery, course through the safe triangle, explaining the frequency of vascular cannulation and the “unsafe triangle” moniker (108). Curved needles may have advantages over straight needles for evading vessels and navigating obstructions (eg, hypertrophic facet joints). If veins compromise supraneural injection, reposition the needle inferiorly and posteriorly in the foramen. This infraneural approach targets the Kambin triangle and favors dorsal and caudal epidural flow (109). The Kambin triangle is bounded by the exiting nerve superiorly, the caudal vertebral body inferiorly, and the facet joint posteriorly. 680 Infraneural placement is more likely to result in annulus fibrosus perforation and inadvertent discography (Fig 12). In patients with foraminal stenosis or lateral disk herniation, target the ventral ramus peripheral to the foramen to avoid severe pain production during injection and failed delivery of medication (Figs 4, 10). NRB at S1 requires epidural needle placement and poses unique access challenges. Both transforaminal and transosseous techniques are feasible after excluding Tarloff cysts and dural ectasia during MR image review. The dorsal S1 foramen is constant in location and orientation but variable in caliber. When the foramen is narrow, transforaminal navigation can be difficult or impossible without meticulous fluoroscopic set-up (Fig 9). A curved needle (5°–10° along the distal centimeter) helps passage through a small angled foramen. Do not rotate a curved needle in the foramen because of the risk of lacerating vessels, including the lateral sacral artery. In patients with osteopenia, a 22-gauge straight needle can be used to penetrate sacral plates with a twisting or oscillating motion. Appropriate epidural depth is determined with lateral fluoroscopy. Trajectory cannot be altered once the needle is drilled through bone. The same transosseous technique can be used to advance a straight needle through a paraspinal fusion mass for lumbar NRB. During most NRBs, expect injection to produce transient radicular symptoms. To avoid the overproduction of severe long-lasting pain, ask patients to control the injection rate. Explain that symptoms should not exceed 5–6 on a 0–10 pain scale. Patients indicate when to inject and when to pause. Patients are reassured by this degree of control; however, stoic individuals may request continued injection despite severe pain because they fear partial steroid dosing. Watch their faces for signs of discomfort, and observe their body language. If the injection rate is too slow, steroid particles can settle in the needle and clog it. When injection pressure unexpectedly increases, reinsert the stylet to clear the needle before a steroid plug completely blocks it. Periodically agitate the syringe to resuspend crystals. NRB generates diagnostic information from pain provocation during needle placement, pain provocation during injection, immediate pain relief from the anesthetic, or delayed pain relief from the corticosteroid. In dictated reports, record the provocative response (pain production during injection) as concordant or nonconcordant and the immediate analgesic response (pain reduction after injection). Selective NRB is intended to yield only diagnostic information. An anesthetic, not a steroid, is injected. In selective NRB, the needle tip touches the ventral ramus peripheral to the foramen and provokes radicular pain that is assessed for concordance with typical symptoms. The volume of anesthetic is limited to avoid spread to nontarget nerves. radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 10 Figure 11 Figure 10: Transforaminal lumbosacral needle placements. Schematic drawing of the lumbosacral spine shows coronal relationships of nerve roots, nerve root ganglia, and postganglionic spinal nerves. In stenotic foramina, extraforaminal needle placement (N1) targets ventral ramus peripherally. In patent foramina, needle placement can be supraneural (N2) in the safe triangle (∗) or infraneural (N3) in the Kambin triangle (cross). At S1, the needle (N4) crosses the posterior S1 foramen and enters the epidural space inferior to the S1 pedicle. Cervical transforaminal injection.— Cervical transforaminal injection is indicated in radiculopathy with or without axial neck pain. Injectionists may follow procedural protocols established by specialty societies, such as the Spine Intervention Society (or SIS) (100–116). The 2004 Spine Intervention Society practice guidelines for cervical NRB recommended intraforaminal positioning of the needle tip as deep as the midpoint of articular pillars but never deeper than a vertical line connecting the uncinate processes (117). After reports of catastrophic neurologic injuries from cervical NRBs, some investigators recommended protocol modifications (55,75,92,118– 120). Potentially safer techniques include extraforaminal needle placement, a lateral or posterior approach, digital Radiology: Volume 281: Number 3—December 2016 n subtraction fluoroscopy, CT guidance, and nonparticulate corticosteroid administration. Others have questioned the benefit of cervical transforaminal injection with any technique, given the difficulty associated with visualization of small vessels, including the radicular artery (84,121,122). To perform fluoroscopy-guided cervical NRB with an anterolateral approach, place the patient in the prone position and turn his or her head away from the side of injection to shift the carotid artery from the needle path. Trajectory modification may be necessary when MR or CT images show an unusually posterior carotid artery or tortuous vertebral artery (123). When MR images are unavailable for procedural planning, reschedule the injection or radiology.rsna.org Figure 11: Oblique fluoroscopic image shows the set-up for lumbar NRB. During anterposterior fluoroscopy (images not shown), the detector was tilted craniocaudally to align the L5 pedicle with the caudal margin of the transverse process (thin curved line), to maximize the space between the L5 transverse process and the sacrum and to standardize osseous relationships for reproducible needle placement. The x-ray beam is parallel to the L5 superior endplate (arrows). The detector was rotated laterally to open supraneural (S) and infraneural (I) routes between the L5 transverse process, lateral facet border (thick curved line), and iliac wing (arrowheads). Degree of rotation depends on morphology of facet and iliac wing, desired needle placement relative to foramen, and straight versus curved needle technique. Straight needle technique requires direct trajectory and, therefore, greater detector rotation. A curved needle may improve navigation through narrow spaces and around hypertrophic facets. position the needle more posteriorly and peripherally than usual, especially in older individuals who might have tortuous arteries. Skip skin anesthesia in case the external jugular vein underlies the desired needle entry site. During the fluoroscopic set-up, target the foramen posteriorly to increase distance from the vertebral artery and inferiorly to access the epiradicular space of the exiting nerve and to improve the likelihood of intraforaminal spread of injectate (Fig 6). Whereas lumbar nerves exit the foramen superiorly, cervical nerves exit it inferiorly. When the needle is positioned too superiorly and peripherally, injectate may flow along the more cranial nontarget 681 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 12 Figure 14 Figure 12: Inadvertant diskogram during NRB in a 51-year-old man with left L3 radiculopathy correlating with L3–4 intraforaminal disk extrusion. (a) Axial T1-weighted MR image at the L3–4 disk level shows a large left intraforaminal disk extrusion (arrowheads) displacing left L3 nerve (white arrow). Right L3 nerve (black arrow) location is normal and surrounded by fat. (b) Anteroposterior fluoroscopic image in the prone position. Curved needles are present on the left side at L3–4 and L4–5. At L3–4, infraneural (retrodiscal) needle (black arrowhead) punctured the disk annulus, resulting in intradiscal contrast (white arrowheads). Radicular symptoms were immediately exacerbated due to distension of the herniation sac (arrow). L4–5 = L4–5 disk space. Figure 13 Figure 13: Inadvertent C7 NRB during attempted C8 NRB in a 44-year-old man with right C8 radiculopathy correlating with C7-T1 intraforaminal disk extrusion. Anteroposterior fluoroscopic image in the supine position shows the needle (arrow) targets right C8 nerve at C7-T1 foramen. Pain provocation prevented further needle advancement. Needle trajectory was satisfactory, but the needle tip terminated peripheral to lateral masses (black lines), distant from the C8 nerve. Injected contrast material (arrowheads) flowed along nontarget C7 nerve into C6–7 foramen between C6 and C7 pedicles. Black = pedicles from C6-T2. 682 nerve (Fig 13). Needle length depends on neck girth and target level, and it ranges from 1.5 to 2.5 inches. Remove any stylet and flush the 25-gauge needle with contrast material, filling the hub prior to insertion to obviate gas delivery. Direct the needle to the lateral margin of the articular pillars, switching between oblique and posteroanterior fluoroscopy to check the needle trajectory and depth. Document extravascular needle placement during contrast material injection with real-time anteroposterior fluoroscopy. Digital subtraction angiography may improve vessel detection (115). Exit veins by advancing the needle several millimeters. If needle advancement fails to result in vein exit, reposition the needle more caudally along the expected course of the target nerve. Short extension tubing (dead space, 0.4 mL) helps to avoid hand exposure during fluoroscopy and inadvertent needle motion during syringe exchange. Inject a nonparticulate corticosteroid. In the cervical spine, nonparticulate and particulate corticosteroids have Figure 14: Targeting midline posterior epidural fat in interlaminar ESI. Midline sagittal reformatted CT image of the lumbar spine and posterior epidural fat at L2–3 (white ∗) indicates safe zone for needle placement in ESI. As a general rule, dorsal epidural fat is most prominent between the bases of spinous processes (white line between black ∗ at L4 and L5) at the disk space level (intersection of white and black lines at L4–5). Needle (N) at L3–4 shows desired tip location in dorsal epidural fat. Needle trajectory projects cranial to disk level (black line at L3–4). In normal spines, L5-S1 has the least dorsal epidural fat. shown comparable short-term effects (116,124). Immediately after needle removal, decrease hydrostatic pressure and the likelihood of hematoma by having patients sit upright. Lumbar interlaminar epidural steroid injection.—Standardized fluoroscopic set-up helps to decrease needle manipulation, radiation dose, and overall procedure time (Figs 14, 15). In younger patients, copious epidural fat and wide interlaminar spaces facilitate successful needle placement. Insert the needle from the side with more severe symptoms, since injectate tends to spread more to the side of needle placement. In older patients, degenerative curvature, spondylotic deformity, interlaminar collapse, bony proliferation, and surgical changes create access challenges. In patients with rotatory radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management Palmer Figure 15 Figure 15: Fluoroscopic set-up for L4–5 interlaminar ESI. (a) After tilting the detector crainocaudally during anteroposterior fluoroscopy (not shown) and projecting L4–5 interlaminar arch (thick curved line) above L4 inferior endplate (arrowheads), laterally rotate the detector 18°–22° to align the apex of the interlaminar arch between the bases of spinous processes (∗). Interlaminar arch at target level should align with arches above and below (curved thin lines at L3-4 and L5-S1). Degree of detector rotation depends on scoliosis and rotatory curvature of spine. Align needle (arrow) between bases of spinous processes for midline needle placement in dorsal epidural fat. (b) Lateral fluoroscopic image shows the needle tip (arrow) enters dorsal epidural space at level of L4–5 disk (straight black line). Needle projects between L4 and L5 spinous processes (curved black lines). Ventral epidural contrast enhancement (arrowheads) is seen. (c) Anteroposterior fluoroscopic image shows midline placement of needle (arrow) between L4 and L5 spinous processes (∗). Left paramedian approach was chosen because of asymmetric disk degeneration causing levoconvex curvature and right-sided interlaminar collapse. scoliosis, approach from the side of the convex curvature to shorten the needle throw (Fig 15). Should the needle tip catch on a lamina or spinous process, turn the bevel toward bone and twist or rock the needle gently until it slides off and advances. Steer away from asymmetrically thickened ligamentum flavum and facet synovial cysts. At the level of hemilaminotomy or hemilaminectomy, interlaminar access should be contralateral to the surgical bed to avoid peridural adhesions that increase risk of dural puncture. A critical juncture approaches as the needle passes through the ligamentum flavum. Initially, when force is applied to the syringe plunger, high pressure prevents contrast material flow. Sudden loss of resistance usually means that the needle has reached the epidural space. Before making the final decision to inject the corticosteroid, carefully observe the contrast material distribution to exclude intravascular, intrathecal, retrodural, or intraligamentous spread. Radiology: Volume 281: Number 3—December 2016 n Assume intravascular injection until proven otherwise (Fig 8). In patients undergoing lumbar interlaminar ESI, the lateral view can show both vascular and intrathecal flow; however, the anterposterior view best excludes vessels when lateral image quality is degraded due to body habitus. To evade vessels, advance the needle, redirect it, or reinsert it at a different level. Intrathecal injection shows immediate dependent layering of contrast material in the subarachnoid space. After dural puncture, ESI can be attempted at a different level or terminated and rescheduled to avoid any possibility of complication due to intrathecal steroid and anesthetic administration. The retrodural space (retrodural space of Okada) can be recognized because it usually communicates with the interspinous space (125,126). The intraligamentous space is associated with facet degeneration and ligamentum flavum delamination (125). In the lateral view, contrast agent distribution initially radiology.rsna.org simulates epidurography, but injection pressure unexpectedly increases after administration of approximately 1 mL of the contrast agent. If lateral and anteroposterior images enable confirmation of interspinous, interlaminar, or facet joint opacification, advance the needle for epidural access. Epidurographic patterns vary considerably between patients and between time points in the same patient (127). Injectate takes the path of least resistance, collecting at the needle tip or spreading over multiple levels. It may flow cephalad or caudad, right or left, circumferentially around the thecal sac or transforaminally along a nerve root. The plica mediana dorsalis, a midline septum that anchors the dural membrane posteriorly, can divide the dorsal epidural space and restrict injectate flow unilaterally. Needle repositioning may be desirable if contrast material spreads contralateral to the side of symptoms. Always inject under low pressure. Spinal stenosis and postoperative 683 HOW I DO IT: Spinal Injections for Pain Management peridural scarring can block free flow of the corticosteroid. When injectate pools locally at a stenotic level or between stenotic levels, anticipate pain production. Symptoms are usually transient when delivering small aliquots and dissipate after 20–30 seconds. When larger volumes are injected quickly, persistent leg symptoms limit delivery of the full dose and force early termination of the procedure. At levels of severe symptomatic spinal stenosis, ESI may exacerbate symptoms that require hospitalization for pain control despite prominent posterior epidural fat. Transforaminal ESI is an NRB variant procedure intended to be semiselective in patients who have unilateral nonradicular symptoms and nonselective in patients who lack interlaminar access due to multilevel laminectomy, hardware, or bone graft. The goal of the procedure is diffuse epidural spread rather than nerve selectivity. Thus, foraminal patency is more important than the exact level of injection. Stenotic foramina should be avoided because of obstructed epidural flow. Although needle placement and initial flow patterns can be identical in transforaminal ESI and NRB, extra diluent disperses the corticosteroid in transforaminal ESI. Lumbar and cervical facet joint injection.—In patients with early osteoarthritis, facet-related pain reflects synovitis or capsulitis and responds to corticosteroid injection. If the steroid breaks the inflammatory cycle, pain relief lasts longer than the drug lifespan. In patients with advanced osteoarthritis, irreversible cartilage loss limits treatment effectiveness. After 6–8 weeks, particulate preparations will have dissipated and symptoms will have predictably returned. Hypertrophic facet degeneration can be managed with periodic injections or with medial branch radiofrequency denervation. Attritional degeneration poses a difficult problem due to the loss of bone stock, causing spondylolisthesis, stenosis, and segmental instability. Invariably, treatment effects do not last as long, or they become nonexistent. Direct needles at cartilage interfaces or capsular recesses (Figs 7, 16). Fluoroscopic set-up should account for 684 Palmer Figure 16 Figure 16: Pars injection via L4-5 facet joint in a 21-year-old woman with low back pain correlating with L5 spondylolysis. (a) Sagittal reformatted CT image of lumbar spine shows continuity between L4-5 facet joint (black arrowheads) and L5 pars defect (white arrowhead). (b) Oblique fluoroscopic image in the prone position shows contrast material filling the needle hub (black arrow) and flowing away from the needle tip into the superior recess (white arrow) of right L4-5 facet joint. Contrast material spreads inferiorly into the conjoined space created by L5 pars defect and inferior L4-5 facet joint recess (arrowheads). Axial CT image (not shown) demonstrated direct access to right L4-5 facet joint at midarticular level approximately 20° off midline. L4 = L4 pedicle, S1 = S1 pedicle. articular orientation, curvature, and degeneration (Fig 1). When osteophytes block the joint space or when listhesis deforms it, target capsular recesses to increase the likelihood of intra-articular needle placement. Periarticular corticosteroid injection may offer the same therapeutic benefits as intra-articular corticosteroid administration (31,128). Document the extra-articular leak of contrast material into a synovial cyst, intraligamentous cavity, or retrodural space (125,126,129). At lumbar levels, synovial cyst rupture is feasible by placing the needle into the facet joint with fluoroscopic guidance or directly into the cyst or facet joint with CT guidance (Fig 7). Facet joints communicate with pars defects; therefore, they can be used to deliver a steroid directly into the pseudoarthrosis (130) (Fig 16). In the cervical spine, both lateral (joint space) and posterior (capsular recess) approaches are feasible. In posterior approaches, displace the mandible by turning the head opposite the symptomatic side. Place pillows under the chest to flex the neck and shorten needle distances. At lower cervical levels especially, decrease the throw by inserting needles perpendicular to the skin. When the needle touches bone, angle the detector parallel to the joint space and move the needle tip superiorly or inferiorly into the joint recess. Conclusion Spine intervention and pain management create rewarding opportunities for radiologists. Radiologists with appropriate training can take responsibility for treatment decisions and outcomes, helping patients delay or avoid surgery. These radiologists build patient-physician relationships, counseling patients with the goal of improving quality of life. Radiologists can leverage their expertise in MR image interpretation to radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management correlate imaging findings with clinical symptoms and establish pain generators. They can use their knowledge of fluoroscopic anatomy to target those pain generators and plan safe and effective needle placement. Acknowledgment: The author thanks Susanne Loomis, MSci, for her expertise in preparation of the medical illustrations and Eleni Balasalle, MEd, for her expertise in the preperation of the supplemental videos. Disclosures of Conflicts of Interest: W.E.P. disclosed no relevant relationships. References 1. Evans W. Intrasacral epidural injection in the treatment of sciatica. Lancet 1930;216(5597):1225–1229. 2. Goebert HW Jr, Jallo SJ, Gardner WJ, Wasmuth CE, Bitte EM. Sciatica: treatment with epidural injections of procaine and hydrocortisone. Cleve Clin Q 1960;27:191–197. 3. Goebert HW Jr, Jallo SJ, Gardner WJ, Wasmuth CE. Painful radiculopathy treated with epidural injections of procaine and hydrocortisone acetate: results in 113 patients. Anesth Analg 1961;40:130–134. 4. Coomes EN. A comparison between epidural anaesthesia and bed rest in sciatica. BMJ 1961;1(5218):20–24. 5. Barry PJ, Kendall PH. Corticosteroid infiltration of the extradural space. Ann Phys Med 1962;6:267–273. 6. Swerdlow M, Sayle-Creer WS. A study of extradural medication in the relief of the lumbosciatic syndrome. Anaesthesia 1970;25(3):341–345. 7. White AH, Derby R, Wynne G. Epidural injections for the diagnosis and treatment of low-back pain. Spine (Phila Pa 1976) 1980;5(1):78–86. 8. el-Khoury GY, Ehara S, Weinstein JN, Montgomery WJ, Kathol MH. Epidural steroid injection: a procedure ideally performed with fluoroscopic control. Radiology 1988;168(2):554–557. 9. Renfrew DL, Moore TE, Kathol MH, elKhoury GY, Lemke JH, Walker CW. Correct placement of epidural steroid injections: fluoroscopic guidance and contrast administration. AJNR Am J Neuroradiol 1991;12(5):1003–1007. 10. Furman MB, O’Brien EM, Zgleszewski TM. Incidence of intravascular penetration in transforaminal lumbosacral epidural Radiology: Volume 281: Number 3—December 2016 n Palmer steroid injections. Spine (Phila Pa 1976) 2000;25(20):2628–2632. 11. Furman MB, Giovanniello MT, O’Brien EM. Incidence of intravascular penetration in transforaminal cervical epidural steroid injections. Spine (Phila Pa 1976) 2003;28(1):21–25. 12. Smuck M, Fuller BJ, Yoder B, Huerta J. Incidence of simultaneous epidural and vascular injection during lumbosacral transforaminal epidural injections. Spine J 2007;7(1):79–82. 13. Smuck M, Tang CT, Fuller BJ. Incidence of simultaneous epidural and vascular injection during cervical transforaminal epidural injections. Spine (Phila Pa 1976) 2009;34(21):E751–E755. 14. Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994;331(2):69–73. 15. Brant-Zawadzki MN, Dennis SC, Gade GF, Weinstein MP. Low back pain. Radiology 2000;217(2):321–330. 16. Johnson BA, Schellhas KP, Pollei SR. Epidurography and therapeutic epidural injections: technical considerations and experience with 5334 cases. AJNR Am J Neuroradiol 1999;20(4):697–705. 17. el-Khoury GY, Renfrew DL. Percutaneous procedures for the diagnosis and treatment of lower back pain: diskography, facet-joint injection, and epidural injection. AJR Am J Roentgenol 1991;157(4):685–691. 18. Deyo RA, Mirza SK, Martin BI, Kreuter W, Goodman DC, Jarvik JG. Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA 2010;303(13):1259– 1265. 19. Frymoyer JW. Back pain and sciatica. N Engl J Med 1988;318(5):291–300. 20. Manchikanti L, Pampati V, Boswell MV, Smith HS, Hirsch JA. Analysis of the growth of epidural injections and costs in the Medicare population: a comparative evaluation of 1997, 2002, and 2006 data. Pain Physician 2010;13(3):199–212. 21. Manchikanti L, Pampati V, Falco FJ, Hirsch JA. Assessment of the growth of epidural injections in the medicare population from 2000 to 2011. Pain Physician 2013;16(4):E349–E364. 22. Friedly J, Chan L, Deyo R. Geographic variation in epidural steroid injection use in medicare patients. J Bone Joint Surg Am 2008;90(8):1730–1737. radiology.rsna.org 23. Friedly J, Chan L, Deyo R. Increases in lumbosacral injections in the Medicare population: 1994 to 2001. Spine (Phila Pa 1976) 2007;32(16):1754–1760. 24. Manchikanti L, Singh V, Pampati V, Smith HS, Hirsch JA. Analysis of growth of interventional techniques in managing chronic pain in the Medicare population: a 10-year evaluation from 1997 to 2006. Pain Physician 2009;12(1):9–34. 25. Levinson DR. Medicare payments for facet joint injection services. Department of Health and Human Services Office of Inspector General on Medicare Payments for Facet Joint Injection Services. http://oig.hhs.gov/ oei/reports/oei-05-07-00200.pdf. Published September 2008. Accessed January 10, 2015. 26. Carrino JA, Morrison WB, Parker L, Schweitzer ME, Levin DC, Sunshine JH. Spinal injection procedures: volume, provider distribution, and reimbursement in the U.S. medicare population from 1993 to 1999. Radiology 2002;225(3):723–729. 27. Abbott ZI, Nair KV, Allen RR, Akuthota VR. Utilization characteristics of spinal interventions. Spine J 2012;12(1):35–43. 28. Friedly JL, Comstock BA, Turner JA, et al. A randomized trial of epidural glucocorticoid injections for spinal stenosis. N Engl J Med 2014;371(1):11–21. 29. Carette S, Marcoux S, Truchon R, et al. A controlled trial of corticosteroid injections into facet joints for chronic low back pain. N Engl J Med 1991;325(14):1002–1007. 30. Carette S, Leclaire R, Marcoux S, et al. Epidural corticosteroid injections for sciatica due to herniated nucleus pulposus. N Engl J Med 1997;336(23):1634–1640. 31. Lilius G, Laasonen EM, Myllynen P, Harilainen A, Grönlund G. Lumbar facet joint syndrome. a randomised clinical trial. J Bone Joint Surg Br 1989;71(4):681–684. 32. Pinto RZ, Maher CG, Ferreira ML, et al. Epidural corticosteroid injections in the management of sciatica: a systematic review and meta-analysis. Ann Intern Med 2012;157(12):865–877. 33. Staal JB, de Bie R, de Vet HC, Hildebrandt J, Nelemans P. Injection therapy for subacute and chronic low-back pain. Cochrane Database Syst Rev 2008;(3):CD001824. 34. Staal JB, Nelemans PJ, de Bie RA. Spinal injection therapy for low back pain. JAMA 2013;309(23):2439–2440. 35. Vad VB, Bhat AL, Lutz GE, Cammisa F. Transforaminal epidural steroid injections in lumbosacral radiculopathy: a prospec- 685 HOW I DO IT: Spinal Injections for Pain Management Palmer tive randomized study. Spine (Phila Pa 1976) 2002;27(1):11–16. root compression. Spine (Phila Pa 1976) 1984;9(1):7–15. 36. Watts RW, Silagy CA. A meta-analysis on the efficacy of epidural corticosteroids in the treatment of sciatica. Anaesth Intensive Care 1995;23(5):564–569. 48. Robinson JP, Brown PB. Medications in low back pain. Phys Med Rehabil Clin N Am 1991;2(1):97–126. 37. Koes BW, Scholten RJ, Mens JM, Bouter LM. Efficacy of epidural steroid injections for low-back pain and sciatica: a systematic review of randomized clinical trials. Pain 1995;63(3):279–288. 38. Riew KD, Yin Y, Gilula L, et al. The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. a prospective, randomized, controlled, double-blind study. J Bone Joint Surg Am 2000;82-A(11):1589–1593. 39. Bresnahan BW, Rundell SD, Dagadakis MC, et al. A systematic review to assess comparative effectiveness studies in epidural steroid injections for lumbar spinal stenosis and to estimate reimbursement amounts. PM R 2013;5(8):705–714. 40. Bush K, Hillier S. A controlled study of caudal epidural injections of triamcinolone plus procaine for the management of intractable sciatica. Spine (Phila Pa 1976) 1991;16(5):572–575. 41. Snoek W, Weber H, Jørgensen B. Double blind evaluation of extradural methyl prednisolone for herniated lumbar discs. Acta Orthop Scand 1977;48(6):635–641. 42. Olmarker K, Byröd G, Cornefjord M, Nordborg C, Rydevik B. Effects of methylprednisolone on nucleus pulposus-induced nerve root injury. Spine (Phila Pa 1976) 1994;19(16):1803–1808. 43. Olmarker K, Rydevik B. Pathophysiology of sciatica. Orthop Clin North Am 1991;22(2):223–234. 44. Olmarker K, Blomquist J, Strömberg J, Nannmark U, Thomsen P, Rydevik B. Inflammatogenic properties of nucleus pulposus. Spine (Phila Pa 1976) 1995;20(6): 665–669. 45. McCarron RF, Wimpee MW, Hudkins PG, Laros GS. The inflammatory effect of nucleus pulposus. a possible element in the pathogenesis of low-back pain. Spine (Phila Pa 1976) 1987;12(8):760–764. 46. Saal JS, Franson RC, Dobrow R, Saal JA, White AH, Goldthwaite N. High levels of inflammatory phospholipase A2 activity in lumbar disc herniations. Spine (Phila Pa 1976) 1990;15(7):674–678. 47. Rydevik B, Brown MD, Lundborg G. Pathoanatomy and pathophysiology of nerve 686 49. Derby R, Lee SH, Date ES, Lee JH, Lee CH. Size and aggregation of corticosteroids used for epidural injections. Pain Med 2008;9(2):227–234. bel changes to warn of rare but serious neurologic problems after epidural corticosteroid injections for pain. http://www. fda.gov/downloads/Drugs/DrugSafety/ UCM394286.pdf. Published April 23, 2014. Accessed January 10, 2015. 50. Benzon HT, Chew TL, McCarthy RJ, Benzon HA, Walega DR. Comparison of the particle sizes of different steroids and the effect of dilution: a review of the relative neurotoxicities of the steroids. Anesthesiology 2007;106(2):331–338. 60. American Society of Anesthesiologists. ASA Formally Responding to FDA Warning on Injection of Corticosteroids into Epidural Space. https://www.asahq.org/ advocacy/fda-and-washington-alerts/ washington-alerts/2014/07/asa-formally-responding-to-fda-warning-on-injection-of-corticosteroids-into-epiduralspace?page=5. Published July 14, 2014. Accessed January 10, 2015. 51. Tiso RL, Cutler T, Catania JA, Whalen K. Adverse central nervous system sequelae after selective transforaminal block: the role of corticosteroids. Spine J 2004;4(4): 468–474. 61. Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc, SIJ or facet joint as the source of low back pain. Eur Spine J 2007;16(10): 1539–1550. 52. Baker R, Dreyfuss P, Mercer S, Bogduk N. Cervical transforaminal injection of corticosteroids into a radicular artery: a possible mechanism for spinal cord injury. Pain 2003;103(1-2):211–215. 62. Schaufele MK, Hatch L, Jones W. Interlaminar versus transforaminal epidural injections for the treatment of symptomatic lumbar intervertebral disc herniations. Pain Physician 2006;9(4):361–366. 53. Kennedy DJ, Dreyfuss P, Aprill CN, Bogduk N. Paraplegia following image-guided transforaminal lumbar spine epidural steroid injection: two case reports. Pain Med 2009;10(8):1389–1394. 63. Lee JH, An JH, Lee SH. Comparison of the effectiveness of interlaminar and bilateral transforaminal epidural steroid injections in treatment of patients with lumbosacral disc herniation and spinal stenosis. Clin J Pain 2009;25(3):206–210. 54. Houten JK, Errico TJ. Paraplegia after lumbosacral nerve root block: report of three cases. Spine J 2002;2(1):70–75. 55. Rathmell JP, Benzon HT, Dreyfuss P, et al. Safeguards to prevent neurologic complications after epidural steroid injections: consensus opinions from a multidisciplinary working group and national organizations. Anesthesiology 2015;122(5): 974–984. 56. Scanlon GC, Moeller-Bertram T, Romanowsky SM, Wallace MS. Cervical transforaminal epidural steroid injections: more dangerous than we think? Spine (Phila Pa 1976) 2007;32(11):1249–1256. 57. Windsor RE, Storm S, Sugar R, Nagula D. Cervical transforaminal injection: review of the literature, complications, and a suggested technique. Pain Physician 2003;6(4):457–465. 58. Okubadejo GO, Talcott MR, Schmidt RE, et al. Perils of intravascular methylprednisolone injection into the vertebral artery. an animal study. J Bone Joint Surg Am 2008;90(9):1932–1938. 59. U.S. Food and Drug Administration. Drug Safety Communications. FDA Drug Safety Communication: FDA requires la- 64. Pfirrmann CW, Oberholzer PA, Zanetti M, et al. Selective nerve root blocks for the treatment of sciatica: evaluation of injection site and effectiveness—a study with patients and cadavers. Radiology 2001;221(3):704–711. 65. Bureau NJ, Kaplan PA, Dussault RG. Lumbar facet joint synovial cyst: percutaneous treatment with steroid injections and distention—clinical and imaging follow-up in 12 patients. Radiology 2001;221(1): 179–185. 66. Jackson RP, Jacobs RR, Montesano PX. 1988 Volvo award in clinical sciences. facet joint injection in low-back pain. a prospective statistical study. Spine (Phila Pa 1976) 1988;13(9):966–971. 67. Revel ME, Listrat VM, Chevalier XJ, et al. Facet joint block for low back pain: identifying predictors of a good response. Arch Phys Med Rehabil 1992;73(9):824–828. 68. Schwarzer AC, Wang SC, O’Driscoll D, Harrington T, Bogduk N, Laurent R. The ability of computed tomography to identify a painful zygapophysial joint in patients with chronic low back pain. Spine (Phila Pa 1976) 1995;20(8):907–912. radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016 HOW I DO IT: Spinal Injections for Pain Management 69. el Barzouhi A, Vleggeert-Lankamp CL, Lycklama à Nijeholt GJ, et al. Magnetic resonance imaging in follow-up assessment of sciatica. N Engl J Med 2013;368(11): 999–1007. 70. Kim KY, Wang MY. Magnetic resonance image-based morphological predictors of single photon emission computed tomography-positive facet arthropathy in patients with axial back pain. Neurosurgery 2006;59(1):147–156; discussion 147–156. 71. Helbig T, Lee CK. The lumbar facet syndrome. Spine (Phila Pa 1976) 1988; 13(1):61–64. Palmer left L2 nerve root injection. Spine (Phila Pa 1976) 2005;30(4):E106–E108. 82. Edlow BL, Wainger BJ, Frosch MP, Copen WA, Rathmell JP, Rost NS. Posterior circulation stroke after C1-C2 intraarticular facet steroid injection: evidence for diffuse microvascular injury. Anesthesiology 2010;112(6):1532–1535. 83. Suresh S, Berman J, Connell DA. Cerebellar and brainstem infarction as a complication of CT-guided transforaminal cervical nerve root block. Skeletal Radiol 2007;36(5):449–452. 72. McCall IW, Park WM, O’Brien JP. Induced pain referral from posterior lumbar elements in normal subjects. Spine (Phila Pa 1976) 1979;4(5):441–446. 84. Hodler J, Boos N, Schubert M. Must we discontinue selective cervical nerve root blocks? report of two cases and review of the literature. Eur Spine J 2013;22(Suppl 3):S466–S470. 73. Cohen SP, Raja SN. Pathogenesis, diagnosis, and treatment of lumbar zygapophysial (facet) joint pain. Anesthesiology 2007;106(3):591–614. 85. Murtagh FR. Computed tomography and fluoroscopy guided anesthesia and steroid injection in facet syndrome. Spine (Phila Pa 1976) 1988;13(6):686–689. 74. Gangi A, Dietemann JL, Mortazavi R, Pfleger D, Kauff C, Roy C. CT-guided interventional procedures for pain management in the lumbosacral spine. RadioGraphics 1998;18(3):621–633. 86. Artner J, Cakir B, Reichel H, Lattig F. Radiation dose reduction in CT-guided sacroiliac joint injections to levels of pulsed fluoroscopy: a comparative study with technical considerations. J Pain Res 2012;5:265–269. 75. Sutter R, Pfirrmann CW, Zanetti M, Hodler J, Peterson CK. CT-guided cervical nerve root injections: comparing the immediate post-injection anesthetic-related effects of the transforaminal injection with a new indirect technique. Skeletal Radiol 2011;40(12):1603–1608. 76. Timpone VM, Hirsch JA, Gilligan CJ, Chandra RV. Computed tomography guidance for spinal intervention: basics of technique, pearls, and avoiding pitfalls. Pain Physician 2013;16(4):369–377. 77. Koizuka S, Nakajima K, Mieda R. CT-guided nerve block: a review of the features of CT fluoroscopic guidance for nerve blocks. J Anesth 2014;28(1):94–101. 78. Wagner AL. CT fluoroscopic-guided cervical nerve root blocks. AJNR Am J Neuroradiol 2005;26(1):43–44. 79. Wagner AL. Selective lumbar nerve root blocks with CT fluoroscopic guidance: technique, results, procedure time, and radiation dose. AJNR Am J Neuroradiol 2004;25(9):1592–1594. 80. Wagner AL. CT fluoroscopy-guided epidural injections: technique and results. AJNR Am J Neuroradiol 2004;25(10):1821–1823. 81. Somayaji HS, Saifuddin A, Casey AT, Briggs TW. Spinal cord infarction following therapeutic computed tomography-guided Radiology: Volume 281: Number 3—December 2016 n 87. Schmid G, Schmitz A, Borchardt D, et al. Effective dose of CT- and fluoroscopyguided perineural/epidural injections of the lumbar spine: a comparative study. Cardiovasc Intervent Radiol 2006;29(1):84–91. 88. Shepherd TM, Hess CP, Chin CT, Gould R, Dillon WP. Reducing patient radiation dose during CT-guided procedures: demonstration in spinal injections for pain. AJNR Am J Neuroradiol 2011;32(10):1776–1782. 89. Smuck M, Fuller BJ, Chiodo A, et al. Accuracy of intermittent fluoroscopy to detect intravascular injection during transforaminal epidural injections. Spine (Phila Pa 1976) 2008;33(7):E205–E210. 90. Hoang JK, Apostol MA, Kranz PG, et al. CT fluoroscopy-assisted cervical transforaminal steroid injection: tips, traps, and use of contrast material. AJR Am J Roentgenol 2010;195(4):888–894. 93. Orth RC, Wallace MJ, Kuo MD; Technology Assessment Committee of the Society of Interventional Radiology. C-arm cone-beam CT: general principles and technical considerations for use in interventional radiology. J Vasc Interv Radiol 2008;19(6):814–820. 94. Leschka SC, Babic D, El Shikh S, Wossmann C, Schumacher M, Taschner CA. C-arm cone beam computed tomography needle path overlay for image-guided procedures of the spine and pelvis. Neuroradiology 2012;54(3):215–223. 95. Horlocker TT, Wedel DJ, Rowlingson JC, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine EvidenceBased Guidelines (Third Edition). Reg Anesth Pain Med 2010;35(1):64–101. 96. Nam KH, Choi CH, Yang MS, Kang DW. Spinal epidural hematoma after pain control procedure. J Korean Neurosurg Soc 2010;48(3):281–284. 97. Bellini M, Barbieri M. Coagulation management in epidural steroid injection. Anaesthesiol Intensive Ther 2014;46(3):195–199. 98. Horlocker TT, Bajwa ZH, Ashraf Z, et al. Risk assessment of hemorrhagic complications associated with nonsteroidal antiinflammatory medications in ambulatory pain clinic patients undergoing epidural steroid injection. Anesth Analg 2002;95(6):1691– 1697. 99. Shetty SK, Nelson EN, Lawrimore TM, Palmer WE. Use of gadolinium chelate to confirm epidural needle placement in patients with an iodinated contrast reaction. Skeletal Radiol 2007;36(4):301–307. 100. Sullivan WJ, Willick SE, Chira-Adisai W, et al. Incidence of intravascular uptake in lumbar spinal injection procedures. Spine (Phila Pa 1976) 2000;25(4):481–486. 101. Kay J, Findling JW, Raff H. Epidural triamcinolone suppresses the pituitary-adrenal axis in human subjects. Anesth Analg 1994;79(3):501–505. 91. Kranz PG, Amrhein TJ, Gray L. Incidence of inadvertent intravascular injection during CT fluoroscopy-guided epidural steroid injections. AJNR Am J Neuroradiol 2015;36(5):1000–1007. 102. Al-Shoha A, Rao DS, Schilling J, Peterson E, Mandel S. Effect of epidural steroid injection on bone mineral density and markers of bone turnover in postmenopausal women. Spine (Phila Pa 1976) 2012;37(25):E1567–E1571. 92. Pottecher P, Krausé D, Di Marco L, et al. Cervical foraminal steroid injections under CT guidance: retrospective study of in situ contrast aspects in a serial of 248 cases. Skeletal Radiol 2015;44(1):1–8. 103. Mandel S, Schilling J, Peterson E, Rao DS, Sanders W. A retrospective analysis of vertebral body fractures following epidural steroid injections. J Bone Joint Surg Am 2013;95(11):961–964. radiology.rsna.org 687 HOW I DO IT: Spinal Injections for Pain Management Palmer 104. Stambough JL, Booth RE Jr, Rothman RH. Transient hypercorticism after epidural steroid injection: a case report. J Bone Joint Surg Am 1984;66(7):1115–1116. rience with a safe and reliable technique using an anterolateral approach for needle placement. AJNR Am J Neuroradiol 2007;28(10):1909–1914. 105. Abram SE. Treatment of lumbosacral radiculopathy with epidural steroids. Anesthesiology 1999;91(6):1937–1941. 115. McLean JP, Sigler JD, Plastaras CT, Garvan CW, Rittenberg JD. The rate of detection of intravascular injection in cervical transforaminal epidural steroid injections with and without digital subtraction angiography. PM R 2009;1(7):636–642. 106. MacMahon PJ, Eustace SJ, Kavanagh EC. Injectable corticosteroid and local anesthetic preparations: a review for radiologists. Radiology 2009;252(3):647–661. 107. Thomas E, Cyteval C, Abiad L, Picot MC, Taourel P, Blotman F. Efficacy of transforaminal versus interspinous corticosteroid injection in discal radiculalgia: a prospective, randomised, double-blind study. Clin Rheumatol 2003;22(4-5):299–304. 108. Glaser SE, Shah RV. Root cause analysis of paraplegia following transforaminal epidural steroid injections: the ‘unsafe’ triangle. Pain Physician 2010;13(3):237– 244. 109. Park JW, Nam HS, Cho SK, Jung HJ, Lee BJ, Park Y. Kambin’s triangle approach of lumbar transforaminal epidural injection with spinal stenosis. Ann Rehabil Med 2011;35(6):833–843. 110. Ma DJ, Gilula LA, Riew KD. Complications of fluoroscopically guided extraforaminal cervical nerve blocks. an analysis of 1036 injections. J Bone Joint Surg Am 2005;87(5):1025–1030. 111. Gilula LA, Ma D. A cervical nerve block approach to improve safety. AJR Am J Roentgenol 2007;189(3):563–565. 112. Wallace MA, Fukui MB, Williams RL, Ku A, Baghai P. Complications of cervical selective nerve root blocks performed with fluoroscopic guidance. AJR Am J Roentgenol 2007;188(5):1218–1221. 113. Kolstad F, Leivseth G, Nygaard OP. Transforaminal steroid injections in the treatment of cervical radiculopathy. a prospective outcome study. Acta Neurochir (Wien) 2005;147(10):1065–1070; discussion 1070. 114. Schellhas KP, Pollei SR, Johnson BA, Golden MJ, Eklund JA, Pobiel RS. Selective cervical nerve root blockade: expe- 688 116. Lee JW, Park KW, Chung SK, et al. Cervical transforaminal epidural steroid injection for the management of cervical radiculopathy: a comparative study of particulate versus non-particulate steroids. Skeletal Radiol 2009;38(11):1077–1082. 117. Bogduk N, Kentfield CA; International Spine Intervention Society. Cervical transforaminal injection of corticosteroids. In: Bogduk N, ed. Practice guidelines for spinal diagnostic and treatment procedures. San Francisco, Calif: International Spine Intervention Society, 2004; 237–248. 118. Hoang JK, Massoglia DP, Apostol MA, Lascola CD, Eastwood JD, Kranz PG. CT-guided cervical transforaminal steroid injections: where should the needle tip be located? AJNR Am J Neuroradiol 2013;34(3):688–692. 119. Wolter T, Mohadjer M, Berlis A, Knoeller S. Cervical CT-guided, selective nerve root blocks: improved safety by dorsal approach. AJNR Am J Neuroradiol 2009;30(2):336–337. 120. Narouze SN, Vydyanathan A, Kapural L, Sessler DI, Mekhail N. Ultrasound-guided cervical selective nerve root block: a fluoroscopy-controlled feasibility study. Reg Anesth Pain Med 2009;34(4):343–348. 121. Huntoon MA. Anatomy of the cervical intervertebral foramina: vulnerable arteries and ischemic neurologic injuries after transforaminal epidural injections. Pain 2005;117(1-2):104–111. with comprehensive analysis of the published data. Pain Med 2014;15(3):386–402. 123. Fitzgerald RT, Bartynski WS, Collins HR. Vertebral artery position in the setting of cervical degenerative disease: implications for selective cervical transforaminal epidural injections. Interv Neuroradiol 2013;19(4):425–431. 124. Dreyfuss P, Baker R, Bogduk N. Comparative effectiveness of cervical transforaminal injections with particulate and nonparticulate corticosteroid preparations for cervical radicular pain. Pain Med 2006;7(3):237–242. 125. Huang AJ, Palmer WE. Incidence of inadvertent intra-articular lumbar facet joint injection during fluoroscopically guided interlaminar epidural steroid injection. Skeletal Radiol 2012;41(2):157–162. 126. Murthy NS, Maus TP, Aprill C. The retrodural space of Okada. AJR Am J Roentgenol 2011;196(6):W784–W789. 127. Whitlock EL, Bridwell KH, Gilula LA. Influence of needle tip position on injectate spread in 406 interlaminar lumbar epidural steroid injections. Radiology 2007;243(3):804–811. 128. Lynch MC, Taylor JF. Facet joint injection for low back pain. a clinical study. J Bone Joint Surg Br 1986;68(1):138–141. 129. McCormick CC, Taylor JR, Twomey LT. Facet joint arthrography in lumbar spondylolysis: anatomic basis for spread of contrast medium. Radiology 1989;171(1):193– 196. 130. Shipley JA, Beukes CA. The nature of the spondylolytic defect. demonstration of a communicating synovial pseudarthrosis in the pars interarticularis. J Bone Joint Surg Br 1998;80(4):662–664. 122. Engel A, King W, MacVicar J; Standards Division of the International Spine Intervention Society. The effectiveness and risks of fluoroscopically guided cervical transforaminal injections of steroids: a systematic review radiology.rsna.org n Radiology: Volume 281: Number 3—December 2016
