Injection Procedures

Injection Procedures (81)

The injection procedures outlined in this chapter are appropriately used in conjunction with other aspects of rehabilitation to reduce pain and increase function. Sterile technique and knowledge of anatomic relationships are required. Aspiration is performed before injecting and is repeated as necessary throughout administration of medication to prevent intravascular injection. For optimal results and safety with injection techniques, the practitioner needs the necessary skill, training, and education to perform the procedures. Haste and failure to observe the necessary precautions by the practitioner increase the risks for any procedure. Knowledge of the anatomy pertaining to each injection procedure is a requirement for safe and successful outcomes in even the simplest injection. 

 

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Joint Injection

Joint Injection (30)

The joint is usually injected from the extensor surface at a point where the synovium is closest to the skin. This site minimizes the interference from major arteries, veins, and nerves. When the point of injection has been determined, it is best marked with the tip of a retracted ballpoint pen or a needle hub by pressing the skin to produce a temporary indentation to mark the point of entry. The skin is then prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure.

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Spinal Injection

Spinal Injection (11)

Spinal pain, especially low back pain (5% incidence and 60% to 80% lifetime prevalence in the United States), is very common (1). Low back pain is the leading cause of disability in people younger than 45 years. Although spinal pain often improves and resolves, a significant proportion of patients have ongoing symptoms and pain recurrence. Low back pain is a costly disorder with an annual cost approaching $50 billion (1). Therefore, a comprehensive rehabilitation approach that improves outcomes for patients with spinal pain can have a significant positive medical and economic impact. Adequate pain control can minimize disability, maximize function, improve quality of life, and potentially improve long-term outcomes by preventing the development of chronic pain syndromes. Spinal injection procedures have become an integral part of comprehensive rehabilitative management for individuals with spinal pain. Judicious use of these interventional procedures on carefully selected patients can provide optimal pain control, reduce disability, and improve functional outcome. This chapter is intended to discuss common spinal interventional procedures in an evidence-based manner and provide some instruction on performance of these procedures.

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Although still controversial, discography (diagnostic intervertebral disc injection) is both an imaging study and a provocative physiologic study for determining whether an intervertebral disc is in fact a pain generator in a given patient (Table 68-7). Inserting a spinal needle into the center of the intervertebral disc and injecting contrast dye provides both physiologic information on whether a degenerative disc is painful and on anatomic features of the intervertebral disc. There is currently no other method to establish reliably whether a disc is a patient’s pain generator.

Clinical Presentation of Discogenic Pain

Patients with lumbar discogenic pain typically have low back pain but can also have pain referred to the buttock, hip, groin, thigh, or distal lower limb. (175). Discogenic pain is typically worse with lumbar flexion and unsupported sitting, as intradiscal pressures have been found to be higher in these positions (176). Physical examination should reveal a normal neurologic examination if the discogenic pathology does not affect the nerve roots.

Radiographic Correlation

MRI and CT of the lumbar spine can be useful initial assessment tools because they are noninvasive tests that allow for visualization of multiple discs. Although they have high sensitivity (Figs. 68-18 and 68-19) for detecting anatomic disc abnormalities, surgically proven internal disc disruption has been reported in cases of normal-appearing MRIs (177). MRI carries a high rate of false-positive findings, as shown in studies of asymptomatic patients (178). In addition, they cannot provide the physiologic information about whether an abnormal- appearing disc is actually a pain generator. Although highintensity signal zones (HIZ) in the posterior annulus on MRI have been linked to discogenic pain (Fig. 68-19), the HIZ can also occur in asymptomatic patients (179–182). With no pathognomonic features of discogenic pain and a high falsepositive rate of anatomic findings on noninvasive diagnostic tests, the diagnosis of symptomatic lumbar disc diseases requires a physiologic study for better clinical correlation of a patient’s pain with CT or MRI abnormalities. Provocation discography is a physiologic test for discogenic pain.

Anatomy and Pathophysiology of Discogenic Pain

The intervertebral disc is a well-innervated structure with A-delta and C-pain fibers (183) containing nociceptive substances such as substance P, calcitonin gene-related product, VIPs in the annulus fibrosis (184–186). Nerve growth factor has been found in both the annulus fibrosis and nucleus pulposus, which may increase pain sensitization (187). In healthy intervertebral discs, only the outer one third of the annulus fibrosis is innervated. Study of intraoperative samples from degenerative intervertebral discs of patients with chronic back pain demonstrated evidence of inward growth of nerve fibers along the radial fissures into the inner annulus (185,186). The presence of the neural structures and nociceptive fibers is believed to be the anatomic basis of chronic low back pain due to degenerative disc diseases. Discogenic pain may occur in internal disc disruption, which is a condition characterized by a degraded nucleus pulposus with radial fissures extending into the peripheral annulus fibrosis (Fig. 68-19) (188,189). The outer margin of the annulus is intact. The nucleus pulposus, reaching the innervated outer annulus through the annular fissures, invokes an intensive local inflammatory process. These inflammatory substances irritate and sensitize the nociceptive fibers in the outer annulus. The threshold for nociceptive mechanical stimulation is lowered in these chemically sensitized nociceptors. Chronic discogenic pain may result from mechanical stimulation of sensitized nociceptors with normal lumbar disc loading. In fact, intraoperative mechanical stimulation of the posterior annulus in the presumed painful segment induced low back pain in one study (190). Degenerative disc disease is believed to account for some 40% of patients with chronic low back pain of unclear origin (191).

FIGURE 68-18. Lateral plain film nucleography demonstrating a posterior annular fissure in the L4-5 and L-S1 discs, respectively, through which contrast leaked into the ventral epidural space. Compare this image with that in Figure 68-23. The nucleography of the L3-4 discs was normal. The patient had concordant back pain at the L4-5 and L5-1 discs but no pain at the L3-4 discs.

FIGURE 68-19. T2-weighted sagittal images of lumbar spine. MRI demonstrating degenerative disc disease, especially at L5-S1.

Indications

Indications for discography appear in the “Position Statement on Discography” from 1988 and 1996 by the Executive

Committee of the North American Spine Society (192):

  • Patients with unremitting spinal pain of greater than 4 months and unresponsive to all appropriate methods of conservative therapy
  • Patients in whom other investigations have failed to explain the source of pain
  • Chronic back pain patients who are contemplating intradiscal or surgical procedures such as spinal fusion

Technique

Discography is generally performed in a radiologic suite or an operating room. The patient is placed in either a prone or oblique side-lying position. A pillow is placed under the patient’s abdomen to reverse lumbar lordosis. The lumbosacral area is prepared and draped in a sterile fashion. The patient’s vital signs should be monitored and oxygen saturation recorded with a pulse oximeter. A peripheral intravenous line should be established for light conscious sedation.

An AP fluoroscopic view is then used to identify the appropriate disc level. The fluoroscope is tilted in either a cephalad or caudad direction to best visualize the target disc space on radiograph. The C-arm is then rotated ipsilaterally to place the superior articular process of the subjacent vertebral body in a position that bisects the vertebral body above. An appropriate size spinal needle, typically a 25-gauge, 3.5-in. spinal needle is used to infiltrate the skin and subcutaneous tissue down to the superior articular process with 1% lidocaine. Caution should be exercised not to inject local anesthetic overzealously in the superior articular process area in order to avoid potential spread to the epidural or nerve root areas, thus compromising the patient’s ability to perceive pain during the subsequent provocative discography. To reduce the chance of discitis, a two-needle technique with 18- or 20-gauge, 3.5-in. introducers and 22- or 25-gauge, 6-in. inner needles, is recommended.

The introducer needle is inserted and directed to the outer edge of the superior articular process in the AP view and just to the anterior border of the superior articular process in the lateral view. The inner needle is then inserted through the introducer and slowly advanced to the center of the nucleus pulposus using alternating AP and lateral views. If the patient complains of radicular pain or paresthesias in a nerve root distribution during needle advancement, the needle should be withdrawn and redirected. If a pressure-controlled system is used for the injection, the needle is connected to an injection system with a manometer that is filled with nonionic and water-soluble contrast. The injectionist then injects contrast slowly, monitoring the pressure reading and the patient’s reports of pain simultaneously. The opening pressure is the pressure reading at the first appearance of dye in the disc on fluoroscopy. The endpoint of the injection occurs when the patient reports concordant pain (defined as reproduction of pain in the same location and intensity), or when 2 mL of total volume is injected into the disc or the pressure reading reaches 90 lb per square inch (psi). To help minimize the chance of discitis, 5 to 10 mg of cefazolin can be injected into each disc before needle removal. One level above and below the disc with concordant pain should be also studied so as to serve as a control (Figs. 68-20 to 68-22).

Information obtained from discography includes the volume of contrast injected, the patient’s pain response (no pain, dissimilar or discordant pain, similar pain, and exact pain provocation or concordant pain), degree of resistance to injection, morphology of the nucleogram, and postdiscogram CT morphology of the disc (193).

FIGURE 68-20. Sagittal T2-weighted lumbar spine MRI demonstrating degenerative disc disease at L5-S1 and possible degenerative disc disease at L4-5 and L3-4.

FIGURE 68-21. Lateral view of lumbar discograms reveals a posterior annular fissure at L4-5 and L5-S1 discs. The discography reproduced the patient’s clinical symptoms (concordant) at L4-5 and L5-S1 discs but no pain at L3-4 discs.

FIGURE 68-22. AP view of lumbar discograms demonstrated left side posterior annular fissures.

Postinjection CT scanning provides an axial view of the injected discs (Fig. 68-23). Patterns of radial and concentric annular fissures are more clearly defined in this plane. Postdiscography CT scanning should be performed within 2 hours of the discogram to prevent diffusion of dye out of the nucleus. The Dallas Discogram Description, in addition to recording the pain and contrast volume injected, describes morphologic degrees of annular degeneration and disruption (194). Annular degeneration and disruption are graded by the percentage of the contrast injected that fills the annulus and annular fissures toward the outer annulus as revealed by the contrast (Table 68-8) (195). A study by Derby et al. found that there was a significant correlation between the extent of annular disruption on CT and the rate of symptomatic disc on discography, with significant differences between grade 3 and 5 versus grade 0 and 2 (196).

FIGURE 68-23. Lumbar postdiscography CT image demonstrating the track of contrast that leaked through a radial fissure into a circumferential outer annular fissure.

A positive discogram requires a concordant pain response, an abnormal nucleogram, and a normal control level. In contrast, multilevel painful discs without a normal control disc on injection are unexplainable and cannot be regarded as positive.

Validity of Discography

In a prospective and controlled study in 1990, by applying modern manometry and postdiscography CT technology, refined needle placement techniques, less irritating contrast dye, stressing concordant pain, or discordant pain in addition to disc morphology (195), Walsh concluded that using stringent criteria, the false-positive rate of lumbar discography in asymptomatic individuals is 0% and the true-positive rate in symptomatic patients is 89% (189). However, Walsh’s study is limited by its small sample size (i.e., only ten controls and seven patients).

In a retrospective study, Derby et al. reported that a patient with a chemically sensitive disc, defined as one having a concordant pain response provoked with intradisc pressure of less than 15 psi as measured by a manometer, has a better outcome with interbody fusion versus intertransverse fusion surgery (197). This better surgical outcome presumably resulted from the removal of the mechanical load or stimulation to the chemically sensitive disc through removal of the painful intervertebral discs and stabilization with interbody fusion (197). Nevertheless, these investigators pointed out that discography should never stand alone as a diagnostic tool and sole factor for a clinical decision. The presence of a chemically sensitive disc does not rule out other coexisting sources of pain, nor does it exclude patients with excessive pain magnification. Discography should be used in conjunction with other diagnostic tests, such as MRI and CT scans, as well as the patient’s history, physical examination findings, response to a comprehensive therapeutic program, and psychometric profile information. Therefore, careful candidate selection is the key to maximizing clinically valuable data from discography. A recent study by Carragee et al. in 2000, although controversial, revealed a high false-positive rate with lumbar discography in a mixed population of 26 asymptomatic patients (182). A significant positive pain response and pain-related behavior with discography were found in 10% of the pain-free group and in 83% of the somatization disorder group. Discs with annular disruption were more likely to be painful on injection. The study concluded that if strict criteria are applied, the rate of false-positive discography may be low in subjects with normal psychometric profiles. Schwarzer et al. in 1995 (183) reported that a discogram is likely to provide highly specific information on the painful lumbar disc when the following characteristics are present: (a) unremitting low back pain persisting after 6 months of conservative care; (b) no prominent psychological dysfunction; (c) injection of all degenerated discs and one normal disc by MRI; or (d) combination of the results of appropriately and carefully performed provocative and imaging tests.

Complications of Discography

Potential complications of discography include discitis (0.05% to 4%), nerve root injury, subarachnoid puncture, chemical meningitis, bleeding, and allergic reaction (192). Use of sterile technique, a two-needle technique, as well as intradiscal antibiotics, can reduce the risk for infection (198).

Summary

In addition to providing imaging of disc morphology, discography is the only provocative physiologic test that can provide information on whether a degenerative disc is the source of pain. In appropriately selected patients, discography is a safe, reproducible, objective diagnostic tool when testing includes volume, pressure, fluoroscopic abnormalities, and pain provocation. Discography results help guide surgical management of chronic back pain. A negative discogram or a multilevel positive discogram without a painless control level can help to exclude a patient as a surgical candidate. Conversely, a singleor double-level positive discogram, along with other clinical data, can help to guide operative planning with respect to fusion or other surgical procedures. This potentially optimizes surgical outcomes. Whether diagnostic discography will actually change surgical outcome depends on many factors, such as a patient’s psychosocial factors, job situation, and the surgical technique employed. The true value of diagnostic discography will likely remain controversial until a prospective, randomized, double-blind, and controlled clinical trial on the outcomes of surgery based on discography is carried out.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Coccyx pain (coccydynia) apparently occurs far less commonly than lumbosacral pain. Coccydynia can be a severe and persistent pain, causing significant suffering, frustration, and functional limitations (199). These patients often have a history of coccyx trauma (e.g., from a fall or childbirth) resulting in contusions, fractures, dislocations, or other injuries. However, other cases are idiopathic. Typical symptoms include focal tailbone pain, particularly worse with sitting and sometimes immediately worse upon going from sit-to-stand (199). Careful screening should seek to exclude malignancies of the spine (e.g., chordoma) and intrapelvic structures (e.g., rectum) (199,200). Useful diagnostic studies may include x-rays, MRI, CT scans, and colonoscopy (199). Dynamic radiographs comparing coccygeal alignment and angulation while sitting (weight bearing on the coccyx) versus standing may reveal dynamic instability (dislocations) not visualized via non—weight-bearing studies (201,202).

Injections for coccyx pain may include focal corticosteroids placed at the posterior coccyx or into a sacrococcygeal or coccygeal joint, ideally performed under fluoroscopic guidance to maximize injection accuracy and minimize the risk for inadvertent puncture of the rectum or other nearby structures. Diagnostic nerve blocks can include local anesthetic blockade of the somatic posterior coccygeal nerve fibers as well as the sympathetic nerve fibers (ganglion Impar) anterior to the coccyx (203–207). For both diagnostic and therapeutic injections, it is frequently helpful to simultaneously block both the anterior (sympathetic) and posterior (somatic) nerves. This combination can more completely shut off all afferent inputs from the coccyx, with resultant relief implying that the coccyx is the source of pain. Also, effective local anesthetic blockade can provide therapeutic benefit, sometimes including complete and permanent relief (208). The mechanism is perhaps via disrupting hyperactive and/or hypersensitive afferent reflex arcs or sympathetically maintained pain. The various technical approaches to the ganglion Impar include injecting a spinal needle from inferior to the coccyx (above the anus), or passing the needle through the sacrococcygeal joint or through the intracoccygeal joints (203–207). Fluoroscopic guidance is crucial for safe and effective performance of sympathetic nerve blocks at the ganglion Impar, especially given the close proximity to the bacteria-laden rectum. Nerve ablation in the coccyx region may be beneficial for selected patients with coccydynia (207). Most patients with tailbone pain will obtain adequate relief via nonsurgical treatments such as injections, thus often avoiding the need for surgery and its potential complications (209).

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

The sacroiliac (SI) joint can be a significant source of low back pain (141–143). Etiologies of SI pain include spondylo arthropathy, crystal arthropathy, septic arthritis, trauma, and pregnancy diasthesis (144). In addition, SI joint dysfunction (pain from a biomechanical disorder without a demonstrable lesion) has been proposed as a possible etiology of SI pain (145). Among patients with chronic low back pain, a study using a single block technique of the SI joint with a local anesthetic, estimated the prevalence of SI joint pain as between 13% and 30% (141). A study on 54 patients with unilateral low back pain suspected from the SI joint, using a dual local anesthetic block technique, demonstrated an 18.5% prevalence of SI joint-based pain (142).

Anatomy and Pathophysiology

The SI joint is a true diarthrodial joint and is innervated by nerves from the L4 through S2 levels (146). Studies on human and animal SI joint capsules demonstrated the presence of mechanoreceptors and nociceptors (147,148). The SI joint has a close anatomic relationship to the lumbosacral plexus and the L5 and S2 nerve roots. Therefore, SI joint pathology such as inflammation or chronic synovial irritation from joint dysfunction can not only serve as a pain generator, but also can potentially involve the nearby neural tissues and induce pain. Injection of the joint with contrast material in healthy volunteers produced pain that extended approximately 10 cm caudally and 3 cm laterally from the posterior superior iliac spine in a linear strip (146). Patients with pain diagrams similar to the SI joint pain mapping were confirmed as having SI pain with SI joint provocation injection (149).

Diagnosis of the SI Joint Pain

The value of clinical data from history and physical examination in the diagnosis of SI joint pain remains controversial (141–143,150,151). Although SI joint pain frequently manifests as pain in the sacral sulcus areas, SI joint pain can refer to the buttock, lower lumbar region, groin, and lower limb (152). However, none of these symptoms, signs or various provocative tests are pathognomonic for SI joint pain. Other sources of low back pain, such as lower lumbar Z-joint arthropathy or degenerative disc disease, can present similarly. By using fluoroscopically guided SI joint blocks to confirm cases of SI joint pain (Fig. 68-17), several authors have shown that clinical medical history and pain provocation tests are not reliable in the diagnosis of SI joint pain (141–143,150,151).

FIGURE 68-17. AP view of right SI joint arthrogram demonstrating contrast in the posterior (medial) and anterior (lateral) joint space. This 23-year-old man complained of persistent right-sided low back pain after a front-impact motor vehicle collision. He was forcefully pressing his right foot on the brake during the collision, with resultant right SI pain. Injecting the right SI joint with 1 mL of 2% lidocaine relieved 90% of his low back pain, lasting several hours. SI joint injections can have both diagnostic and therapeutic benefits.

In a clinical trial involving 84 patients with possible low back pain from the SI joint, Dreyfuss et al. studied clinical history and the 12 physical examination tests deemed most reliable by a panel of experts for isolating SI joint pain (143). Fluoroscopically guided intra-articular SI joint injections of local anesthetic and corticosteroid were performed to confirm the diagnosis. The criterion for a positive result was the achievement of at least 90% pain relief postinjection. The study demonstrated that neither the history nor the physical examination data was of significant value in diagnosing SI joint pain (141). Maigne et al. investigated 54 patients with clinical features of chronic low back pain compatible with the origin in the SI joint with the following features: unilateral buttock pain, tenderness over the SI joint, normal lumbar CT scan, failure of previous epidural, or facet injections (142). They applied seven “SI pain provocation tests” before and after the dual block of SI joint. To be considered diagnostic, patients had to report 100% pain relief after block with 1% lidocaine and at least 75% pain relief after block with 0.25% marcaine. There was an 18.5% rate of positive responders to this dual block. The result demonstrated that none of the SI joint pain provocation tests were able to isolate SI joint pain (142). Slipman et al. performed a diagnostic fluoroscopically guided SI joint injection in 50 consecutive patients with low back pain presumed to be from SI joint (162). A reduction of the VAS rating by at least 80% was considered a positive response to SI joint block. The authors concluded that the various SI joint provocative maneuvers were not useful in diagnosing SI joint pain (162). A diagnostic imaging study done with bone scan was found to have low sensitivity and high specificity for diagnosing the SI joint syndrome (149). This study excluded patients with SI joint pain from inflammation, such as in a seronegative spondyloarthropathy. However, another study using single photon emission CT (SPECT) was performed in 54 patients with symptoms of low back pain of at least 3 months duration, the presence of higher erythrocyte sedimentation rate, and higher C-reactive protein levels who had not received anti-inflammatory drugs. The results demonstrated high sensitivity (97%) and specificity (90%) in diagnosing inflammatory disease within SI joints (153).

Indications

Although exact guidelines for administering an SI joint injection are unclear, one set of guidelines is as follows: a diagnostic SI joint injection is indicated in patients with pain over the sacral sulcus who have failed to respond to 4 to 6 weeks of directed physical therapy and oral nonsteroidal anti-inflammatory agents (154,155).

Technique

The patient is placed in a prone position. The skin over the sacral area is prepped and draped in a sterile manner. By rotating the C-arm fluoroscope slightly contralaterally, but occasionally ipsilaterally, intermittent fluoroscopy is used to identify the medial joint line when it just separates from the lateral joint line of the SI joint. Some adjustment of the C-arm in the caudal or cephalad plane may then be used to best isolate and visualize the lower portion of the SI joint. The targeted area is the small lucent area just below the joint line. The skin entry site is selected slightly lower than the targeted area, and is infiltrated with a small amount of 1% lidocaine. A 22- or 25-gauge 2.5 to 3.5-in. spinal needle is inserted and directed down to contact the ilium. The needle is then withdrawn 2 to 3 mL and redirected toward the inferior-medial aspect of the joint into the lucent area (156). Typically, the needle tip will bend if it enters the SI joint, and a tactile sense of a sliding into the joint will be appreciated (157). Applying a slight curve at the tip of the needle prior to use may help assist this process (156). A small amount of contrast is then injected to outline the SI joint. If the needle fails to plunge and no contrast flow is seen on fluoroscopy, one technique advocates that the needle be slowly extracted a millimeter at a time, while continuing to maintain pressure on the plunger until there is a loss of resistance (157). Once an SI joint arthrogram without a vascular uptake pattern is demonstrated, anesthetic with or without steroid is injected (depending upon if the injection intent is for therapeutic or diagnostic use, respectively). One milliliter of 2% lidocaine or 0.5% bupivacaine mixed with 40 mg/mL of triamcinolone acetonide, or other equivalent corticosteroid, is injected into the SI joint (158–161). A total of no more than 2.0 mL of volume is generally injected due to the limited volume of the SI joint (160).

Efficacy

Diagnostic Injection of SI Joints

Because the gold standard for proof of SI joint pain is unclear, the sensitivity and specificity of diagnostic SI joint injections has not been clearly established.

Maigne et al. (142) have suggested that the SI joint block has diagnostic value only for pain from intra-articular sources, not for SI joint pain from extra-articular sources such as the periosteum, interosseous ligaments, erector spinae muscles, or fascial elements, all of which contain nociceptors and hence are possible pain generators (147,148). Therefore, an SI joint block procedure that involves injection of an agent into the extra-articular components rather than the joint cavity may show better correspondence to the clinical features. Future studies should address whether the combination of pericapsular and intra-articular SI joint injection with corticosteroid can improve outcomes.

Therapeutic Injection of the SI Joint

The efficacy of SI joint corticosteroid injections has been reported in prospective and retrospective studies of patients with spondyloarthropathy (163,164). In a retrospective study, Slipman et al. reported a significant benefit from SI joint steroid injection in patients with SI joint syndrome (165). Thirty-one patients with chronic SI joint syndrome received an average of 2.1 fluoroscopic-guided SI joint corticosteroid injections. The average follow-up was 94.4 weeks. Of the 29 patients who completed the study, there was a significant improvement in the Oswestry disability score, VAS, and work status (165). Although these retrospective results are encouraging, there are currently no prospective studies on the efficacy of fluoroscopically guided therapeutic SI joint corticosteroid injections.

Radiofrequency Ablation of the SI Joint

Radiofrequency ablation (RF-A) has recently been proposed as a potential long lasting treatment for SI joint pain, and has been gaining more popularity along with other nonsurgical spinal procedures. RF-A involves de-innervation of the SI joint nerves believed to be responsible for generating pain (166,167). It is indicated as a treatment for those patients who have failed more conservative measures, yet only received transient benefit from diagnostic and/or therapeutic injections of the SI joint (168). The true effectiveness of RF-A of the SI joint is unclear, as of yet (169). In contrast to RF-A in treating lumbar spine facet-mediated pain, which directly targets the medial branches of the dorsal rami, which innervate the facet joints (170), the SI joint has complex innervations (171). Therefore, no consistent procedural technique has been described in the literature. Multiple studies have, in fact, been done using various techniques for RF-A of the SI joint, which are summarized in Table 68-6. The table shows that there are variations among the techniques used in regard to structures, nerves, and patterns of ablation to the SI joint.

The table underscores the fact that there is no standard pattern of ablation and not enough available prospective data to determine which rami or branches should be ablated, or if a pattern technique (i.e., “leap frog” vs. “strip lesion”) is more efficacious. The studies do not show uniformity and additional studies to determine if RF-A is useful for treating chronic SI joint pain are warranted.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Radiofrequency neurotomy interrupts the nociceptive afferent from the Z-joint by thermally coagulating the two medial branches that innervate a given Z-joint. The exposed terminal portion of radiofrequency probe delivers heat at 80°C. For each Z-joint (except the C2-3 joint, which is innervated by the third occipital nerve), two medial branches need to be ablated.

Indications

Radiofrequency neurotomy can provide relative long-term benefit symptoms from persistent or recurrent Z-joint pain despite conservative care (that have had transient benefit from Z-joint injections), and for patients with substantial (e.g., at least 80%) pain relief after dual blocks of the medial branch with two local anesthetics of different duration on two occasions.

Technique

Lumbar Medial Branch Neurotomy

Since the “groove” at the junction of the superior articular process and the transverse process can be clearly viewed in a certain fluoroscopic position, this “groove view” has been proposed for the starting position of a lumbar medial branch neurotomy. Specifically, the C-arm intensifier is obliqued ipsilaterally approximately 10 to 15 degrees and tilted cephalad 20 degrees. A 22-gauge 100 mm radiofrequency probe with a 5-mm active tip is then introduced using the “tunnel view” until it contacts the bone and advanced along the “groove” where the medial branch resides. The radiofrequency probe creates an effective circumferential lesion around the probe but does so poorly distal to the tip. To avoid incomplete heating, the radiofrequency probe needs to be placed on and parallel to the path of the medial branches crossing the transverse processes. In AP imaging, the needle should be medial to the lateral silhouette of the superior articular process. A lateral view should be obtained to ensure that the needle is not positioned anterior to the posterior aspect of the neuroforamen. Motor stimulation using 2.0 Hz and less than 2.0 V should not induce any muscle twitching or movement in the lower extremity. A single lesion at 80 degrees celsius for 60 seconds is performed. A second and third lesion is performed after repositioning the needle 1.0 mL cephalad and caudad to ensure proper coagulation of the length of the medial branch.

Cervical Medial Branch Neurotomy

For cervical medial branch ablation, the patient is placed in a prone position and the C-arm is tilted in a cephalad direction to obtain a pillar view. The first radiofrequency lesioning probe is inserted parallel to the articular pillar, directed down the fluoroscopic beam and slightly medial until it touches the dorsal aspect of the pillar. The needle is then walked lateral until it slips off the bone. A second radiofrequency probe is inserted with approximately 30 degrees of ipsilateral obliquity and slightly caudad so that this needle can be positioned more anteriorly. The rest of the needle advancement is the same as for the first needle. This dual needle placement positions the two probes to allow subsequent adequate denervation along the entire length of the medial branch. Prior to lesioning, a lateral view is taken to ensure that the tips of the radiofrequency probes are not anterior to the anterior margin of the articular pillars. Motor stimulation is conducted at a frequency of 2.0 Hz and at less than 2.0 V intensity. If muscle twitching or upper extremity movement occurs, this indicates that the radiofrequency probe is too close to the anterior rami and needs to be repositioned. Next, 0.5 mL of 1% lidocaine is injected through the radiofrequency cannula. A lesion is then performed at this position at 80°C for 60 seconds. The probe is then repositioned 1 mm caudad and cephalad, respectively, and two additional lesions are made for a total of six lesions using the two radiofrequency probes. A similar technique is employed for the third occipital nerve.

Efficacy

Proper patient selection is the key for optimal outcome from radiofrequency neurotomy. One recent prospective study has demonstrated good efficacy from the procedures when patients with presumed Z-joint pain are selected using the double block paradigm with comparative local anesthetic (130). The patients were diagnosed with a lumbar Z-joint pain if they obtained at least 80% pain reduction after medial branch blocks with 0.5 mL of 2% lidocaine on one occasion and 0.5% bupivicaine on another. At 12 months following the radiofrequency medial branch neurotomy, 60% of patients achieved at least 90% pain reduction and 87% of patients had 60% pain relief. The success of denervation was seen in virtually all patients as demonstrated by post-radiofrequency needle EMG of the corresponding segmental multifidi (130). The initial population of 41 patients accepted into the study and clinically felt to have facet-mediated pain was reduced to only 15 candidates for actual RFA, which further emphasizes the importance of double-block screening for Z-joint pain diagnosis. A recent randomized study using single Z-joint blocks for selecting patients with subsequent radiofrequency neurotomy demonstrated modest success with an average VAS pain reduction of 2.0 points in 66.7% of the lesion group versus 35.7% of sham group patients at 8 weeks to 12 months follow-up (131). An obvious concern with this study is that the criteria for a positive block mandated a relatively low threshold of only 50% pain relief, and 40 of 92 patients subjected to the diagnostic block had a positive response in this regard. This would imply a prevalence of facet joint pain higher than what has been reported in most populations. Another study showed no treatment effect at 12 weeks, as assessed by the Roland-Morris scale (2.6% change) and Oswestry scale (1.9% change) and VAS (–7.6% change) (132). Again, the known 38% false-positive rate for a single-block makes the study results and conclusions less convincing (126,133).

Efficacy of radiofrequency neurotomy for cervical Z-joint pain (other than from the C2-3 joint that was excluded from this study), has also been demonstrated in a randomized, double-blinded, and placebo-controlled trial (134,135). The patients were selected by placebo-controlled medial branch blocks. The total duration of pain relief was defined as the period until the patient judged that pain had returned to 50% of the pre-procedural level. Twenty-four patients were randomized into radiofrequency neurotomy and sham radiofrequency neurotomy (radiofrequency probes placed but radiofrequency was not turned on) groups. Fifty percent pain relief lasted 263 days in the radiofrequency group and 8 days in a controlled group. A second study of 28 patients with long-term follow-up and repeat radiofrequency neurotomy demonstrated a median duration of pain relief of 422 days. In the 11 patients who underwent repeat radiofrequency neurotomy, the median duration of pain relief was 219 days. The authors concluded that radiofrequency neurotomy provides clinically significant pain relief, and can be repeated if pain recurs (136).

Recent review articles on randomized controlled trials of radiofrequency neurotomy for spinal pain concluded that RF neurotomy was efficacious for both chronic low back pain and neck pain after flexion-extension injuries (124), and that there is evidence of moderate strength for use of RFA in the cervical and lumbar spine (129).

Complications

Potential complications of fluoroscopic-guided, contrastenhanced lumbar Z-joint injections or medial branch blocks are rare. The most common post-procedural problem is transient pain at the injection site. However, there have been rare case reports of meningitis, inadvertent spinal anesthesia, and infection after Z-joint injections (137,138). Recurrent back and neck pain after radiofrequency neurotomy may be due to incomplete ablation or medial branch regeneration (139). Since the dorsal root ganglia are left intact, the ablated medial branches may regenerate. Because radio frequency neurotomy does not permanently denervate the Z-joints or cause inherent instability in the spine, the concern of Charcot facet joint development has little ground and no such cases have been published (140). Also, because the DRG remains intact, deafferentation pain should not occur. Side effects from radiofrequency neurotomy are rare when the procedure is performed correctly but include local pain and infection.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Introduction

The prevalence of lumbar zygapophyseal joint (Z-joint) pain has been reported to be approximately 6% in a primary care setting (94). However, in a tertiary spine center, lumbar Z-joint pain has been reported to range from 15% in younger individuals (96) to 40% in older populations (98) with chronic low back pain. In individuals with chronic neck pain after a whiplash injury, Z-joint pain occurred in approximately 50% of patients (99,100). More recent literature examining 500 patients has reported a prevalence of 55% cervical facet joint pain, 42% thoracic facet joint pain, and 31% lumbar Z-joint pain in patients with chronic spine pain identified with a double block model as described later (95). Lumbar facet joint pain has been reported in 16% of patients with chronic postsurgical lumbar spine pain (97). Studies of a larger population using a dual anesthetic block paradigm may be helpful in further identifying the prevalence in the general population for both acute and chronic low back pain.

Anatomy

Z-joints are pairs of small synovial joints in the posterior aspect of the spine, formed when the inferior articular process of one vertebra articulates with the superior articular process of the subjacent vertebra. Each lumbar Z-joint has a 1 to 2 mL capacity (101). Cervical and thoracic Z-joints can hold volumes of less than 1 mL (103) and 0.5 to 0.6 mL (104,105), respectively.

The Z-joint at C2-3 is innervated by the third occipital nerve from the superficial medial branch of the C3 dorsal ramus. Below the C2-3 Z-joint, each cervical Z-joint is innervated by the medial branches from the level above and below. The medial branches wrap around the articular pillar transverse processes. The C7 medial branch is located higher, as it is pushed up by the base of the transverse process. The joints between C0-1 (atlanto-occipital) and C1-2 (atlantoaxial) joints are technically not Z-joints, due to their anterior location. They are innervated by the anterior rami of C1 and C2, respectively. Significant variability in the location of the medial branches has been reported, particularly with regard to the anatomy in the cervical spine (102).

The medial branches innervating the thoracic Z-joints have a different course in relation to the transverse processes (105). The thoracic medial branches instead wrap around the junction between the transverse process and the superior articular process. As in the lumbar spine, they often exit in the middle portion of the intertransverse space, and they typically cross the superolateral corners of the transverse processes and then pass medially and inferiorly across the posterior surfaces of the transverse processes. Furthermore, at mid-thoracic levels (T5-8), the inflection occurs at a point superior to the superolateral corner of the transverse process. Therefore, the superolateral corners of the transverse processes are generally the more accurate target points for diagnostic blockade or radiofrequency denervation of the thoracic medial branches.

In the lumbar spine, each Z-joint is innervated by two medial branches of dorsal rami; one from the same level and the other from the level above (106). For example, the Z-joint at L4-5 is innervated by the medial braches of the L4 and L3 dorsal rami. The medial branches travel along the junction of transverse process and superior articular process. After exiting the mamilloaccessory notch covered by the mamilloaccessory ligament, the medial branches send branches to innervate the same level of the Z-joint and the Z-joint below. However, the L5 dorsal ramus crosses the groove between the sacral ala and the superior articular process of the sacrum. The L5 medial branch to the L5-S1 Z-joint is very short because it does not branch out until it comes just under the L5-S1 Z-joint. It is important to remember that the lumbar medial branch rests on the subjacent level rather than the same level of the transverse process. For example, the L3 medial branch rests on the L4 transverse process rather than on the L3 transverse process (Figs. 68-12 and 68-13). Therefore, to denervate the L4-5 Z-joint, it is necessary to target the L3 and L4 medial branches, which rest on the junction of L4 and L5 transverse processes and superior articular processes, respectively. One exception is the blockade or denervation of the L5 medial branch. Due to the short branch below the Z-joint, denervation of the L5 medial branch can only be performed by destruction of the L5 dorsal ramus proper at the groove between the sacral ala and the superior articular process.

FIGURE 68-12. AP view of left L5-S1 Z-joint (facet) arthrogram. Notice the contrast pooling in the superior and inferior articular recesses. This 33-year-old man injured his low back lifting a 70-lb piece of metal overhead. Unable to sustain the weight, he extended his low back obliquely to the right side to drop the metal. He felt a “pop” in his left low back and sustained persistent significant left low back pain. Several minutes after this left L5-S1 intra-articular Z-joint injection with 0.5 mL of 1% lidocaine, his low back pain was completely abolished.

FIGURE 68-13. AP lumbar MBB at the right L2, L3 and L4 vertebral levels, demonstrating needle tips and contrast injected at the base of SAPs and the transverse processes.

Pathophysiology of Z-joint Pain

The Z-joint is a well-innervated structure. The Z-joint capsule contains both nociceptive and mechanosensitive receptors (101,106–108). Immunocytochemical studies have demonstrated that the Z-joint capsule or synovial folds contain substance P, calcitonin gene-related product, vasoactive intestinal polypeptide (VIP) and neuropeptide, and tyrosine hydroxylase (101,107,108). Ostensibly, the Z-joint capsule is a potential pain generator if it is injured. In addition, like any synovial joints, Z-joints can develop synovitis under certain circumstances.

Typical Z-joint pathology often derives from pathologic mechanical stress or inflammation. In the lumbar spine, the sagittal orientation of upper lumbar Z-joints and the relative lateral oblique orientation of lower lumbar Z-joints make them vulnerable to injury from extension and torsion forces. In the cervical spine, both human and animal studies of whiplash injuries have demonstrated evidence of multiple pathologic findings, including Z-joint capsule tearing, intraarticular hemorrhage, articular cartilage, muscle injury, and subchondral bone fracture (110). These pathologic changes can serve as a basis of pathologic nociception and neck pain. However, none of these pathologies can be detected with conventional imaging studies (110).

Patients with lumbar Z-joint pain often have more pain in the lateral aspect of the low back unilaterally or bilaterally but not centrally (111). Pain can often be made worse with oblique extension of the lumbar spine (111,112). Pain is often worse after overnight rest or inactivity. Local tenderness and “muscle spasm” over the involved Z-joint are frequently noted. Although Z-joint pain can present with referred pain, groin pain or thigh pain, neural tension signs are negative and there are generally no neurological deficits, though recently a study where a rat model was used to induce Z-joint inflammation has documented associated radiculopathy as a possible sequela (109). Patients with cervical Z-joint pain experience pain located in the axial cervical areas. However, several studies have failed to demonstrate any pathognomonic physical exam findings of Z-joint pain (111,112). Imaging studies are also unable to confirm or refute the diagnosis of Z-joint pain (110,113,114).

Indications

Given the lack of a clinical diagnostic gold standard, clinicians have used regional anesthesia to identify Z-joint pain. Abolishment of low back pain after anesthetic Z-joint injection or medial branch block confirms the Z-joint as the pain generator (Figs. 68-14 and 68-15). Z-joint injection is indicated in patients with acute back and neck pain of suspected Z-joint origin, with no evidence of neurologic deficits, and whose pain pattern resembles that evoked in normal volunteers upon stimulation of their Z-joints. However, since the majority of acute back and neck pain, including Z-joint pain, will resolve in several weeks, the injection is often reserved for individuals with severe pain that has failed to respond to 4 to 6 weeks of conservative therapy including oral analgesics, directed physical therapy, and relative rest. Fortunately, injection can be performed earlier if pain is inhibiting therapy progress.

FIGURE 68-14. Oblique view of left L4-5 Z-joint injection showing the needle tip inside the Z-joint space.

FIGURE 68-15. Oblique view demonstrating blocks of right L1, L2 and L3 medial branches at the right L2, L3 and L4 pedicles, viewed as the “eyes of the Scotties dogs”, at the base of the SAPs and transverse process where the medial branches are located.

Contraindications

As is true of all spinal injection procedures, Z-joint injections are contraindicated in individuals with the following conditions: infection, bleeding diathesis, pregnancy (for use of fluoroscopy), allergy to the medications to be injected (contrast medium, local anesthetics, corticosteroid), and unstable medical conditions such as unstable angina or poorly controlled hypertension or diabetes mellitus. Injections are elective procedures, so an effort should be made to properly select patients so as to ensure safety and optimize outcome.

Techniques

For lumbar Z-joint injection, the patient is placed in a prone position with a pillow under the abdomen to distract the Z-joint. After sterile preparation and skin draping, intermittent fluoroscopic views are used to identify the level of the Z-joint. For the L5-S1 level, the fluoroscope is tilted in a caudad direction to accommodate the lumbar lordosis, and rotated ipsilaterally until the joint space first comes into view, which is the posterior opening of the Z-joint, that is, the needle entry point. Although further rotating the image intensifier will more clearly visualize the Z-joint space, the visualized joint space at this angle is actually the middle or anterior Z-joint opening, not the posterior opening which is the injectionist’s target. For upper lumbar Z-joint injections, it may require less oblique rotation to better visualize the Z-joint space. The needle entry site is marked with a metal instrument. The skin and the underlying tissues are infiltrated with 1% lidocaine. For diagnostic Z-joint injections, the underlying tissues should not be infiltrated with anesthetic in order to maximize injection specificity. A 22- or 25-gauge 3.5 in. spinal needle is then inserted at the anesthetized site and directed toward either the superior or inferior articular processes of the targeted facet joint using a “tunnel view” technique by which the entire needle shaft is paralleled to the fluoroscopy beam in such a way that the needle hub appears as a dot. Once the needle contacts the bone, the tip of the needle is then “walked” off into the Z-joint space. Occasionally, due to the osteoarthritic changes, the needle cannot gain entry. The needle can then be directed into the inferior articular recess just off the lower margin of the articular processes. Once the needle is felt to be in the articular space or to have penetrated the Z-joint capsule, 0.2 to 0.3 mL of the water soluble and nonionic contrast is injected to outline the Z-joint and to confirm that the needle tip is not located inside the vascular or epidural space. For therapeutic benefit, 1.0 mL of a mixed solution containing 20 mg of methylprednisolone acetate and 1% lidocaine is slowly injected into the Z-joint.

Medial Branch Block

For lumbar medial branch blocks, skin preparation and C-arm fluoroscope positioning are essentially the same as for Z-joint injections. The difference is the target, which is the “Scottie dog’s eye” rather than “ear,” because the former represents the anatomical site where the medial branch is situated whereas the latter represents the articular processes forming the Z-joint. After local skin is infiltrated with 1% lidocaine, a 22- or 25-gauge 3.5 in. needle is inserted and directed until the needle touches the middle portion of the “Scottie dog’s eye.” The fluoroscope is then turned to the cross table or lateral view; the needle should be located at the site posterior to the spinal lamina. At the anterioposterior (AP) view, the needle tip should be at or slightly medial to the lateral margin of the superior articular process. At this point, the needle bevel should be turned to face medially, and 0.2 to 0.3 mL of the contrast is injected under real-time fluoroscopy to ensure that a vascular pattern or neuroforamial spread upon the dye injection has occurred. To ensure block specificity, less than 0.5 mL of either 2% lidocaine or 0.5% bupivacaine is used to block each medial branch.

For block of the L5 dorsal ramus, the fluoroscope should be rotated ipsilaterally oblique about 10 to 15 degrees. The needle is then directed in “tunnel view” down to the junction at the superior articular process of the S1 vertebra and the ala of the sacrum. In the AP view, the needle tip should be at the lateral margin of the S1 superior articular process.

Efficacy

Diagnostic Z-joint Injection or Medial Branch Block

The literature has demonstrated that Z-joint injections and medial branch blocks can be used for the diagnosis of Z-joint pain with comparable sensitivity and specificity (Fig. 68-16) (115–118). A medial branch block may be relatively easier to perform with less trauma to the Z-joint. In the cervical spine, medial branch blockade has been shown to be a valid technique for the diagnosis of Z-joint mediated pain (119). Overall, medial branch blockade has a reported 89% specificity and 11% false-negative rate (118).

FIGURE 68-16. Lateral view of cervical Z-joint injection, with the arthrogram demonstrating the typical dumbbell shape.

Since the degree of pain relief is a patient’s subjective response, Z-joint injection or medial branch blockade is susceptible to a placebo effect. Other possible causes of falsepositive studies include inadvertent anesthetic spread to pain generators outside of the Z-joint. Research has shown falsepositive rates of 27% to 38% for lumbar blocks, 27% to 63% for cervical blocks, 55% for thoracic blocks, and a 32% placebo effect (95,112,120,121). To minimize false-positive rates, various clinicians have advocated evaluating the response to injecting anesthetics of varying anesthetic durations as well as possibly performing a control injection with saline placebo. A true-positive response is considered to be pain relief lasting for 1 to 2 hours with 2% lidocaine, and 3 to 4 hours with 0.5% bupivacaine, but no effect with saline. However, such a triple block scheme requires three separate procedures and is thus time consuming and costly. Ethical issues arise if a patient accepts the procedural risks and financial costs expecting a therapeutic injection, only to receive a placebo injection. A compromise is to perform a “double block paradigm” using two local anesthetics with different durations of action, one on each of two separate occasions. If each of the two injections relieves pain for the duration expected for the anesthetic used, Z-joint pain can be reliably diagnosed. Published studies have validated this dual blockade paradigm, using comparative local anesthetics for medial branch blocks to anesthetize Z-joints, which constitutes a viable alternative to normal saline controls (100,122).

Potential causes of false-negative responses include venous uptake of the injected anesthetic, aberrant innervation of the target Z-joint, and other technical issues. Since both intravascular injection and epidural spread of injectate can reduce the injection specificity, fluoroscopy plays an important role in maximizing outcomes.

If injection is being performed solely for diagnostic, not therapeutic, purposes, then only local anesthetic should be injected, without corticosteroid. Regarding the placebocontrolled blocks, a positive diagnosis was recorded only if the patient’s pain was completely and reproducibly relieved by each of the local anesthetic but not via the normal saline.

As stated above, double block with local anesthetics of different durations on two separate occasions can reduce (although not eliminate) the false-positive response and placebo effect (122). What constitutes a positive diagnostic response remains the physician’s subjective judgment. For a true concordant response with comparative blocks (100), the patient should obtain complete pain relief with a duration that is consistent with each particular anesthetic solution, though recent published placebo-controlled studies have used a criterion of at least 80% pain relief. This concordant response criterion for identifying Z-joint pain yields a good specificity of 88%, but only marginal sensitivity of 54%, thus suggesting significant false-negatives (100). Expanding the comparative blocks diagnostic criteria to include all patients with reproducible relief, irrespective of duration, increases sensitivity to 100% but lowers specificity to 65% (100). Whether the criterion should be structured to more aggressively prevent false-positive responses versus to prevent false-negative responses may depend on what subsequent treatment will be based on the determination. For additional treatments that can irreversibly alter the patient’s anatomy (e.g., via surgery or radiofrequency ablation [RFA]), preventing false-positive responses becomes increasingly important (100).

Using the dual block technique in patients with chronic low back pain, lumbar Z-joint pain was demonstrated in 15% of younger patients and 40% of older patients (96,98). In chronic neck pain after whiplash injury from motor vehicle injury, Z-joint pain occurred in 54% of patients (99). Another study of patients with chronic neck pain for more than 6 months demonstrated that the prevalence of Z-joint pain was 36% (123). The C2-3 and C5-6 Z-joints were found to be the most common symptomatic joints (99,123). The C2-3 joint was found to be a pain generator in 50% of patients with chronic cervicogenic headache after a whiplash injury (99). It is interesting that using the intra-articular and/or medial branch block, studies have demonstrated that the coexistence of Z-joint pain and discogenic pain in lumbar region is only 4%, while in the cervical spine it is 40% (124,125).

Caution should be exercised using provocation of pain as a sole diagnostic criterion for patient undergoing a diagnostic lumbar Z-joint injection. One study has demonstrated no significant correlation between pain provocation during Z-joint injection and the analgesic response (126).

Therapeutic Effect

The therapeutic benefit of Z-joint injection with corticosteroids remains controversial (127). A past study has suggested positive efficacy of C2-3 Z-joint corticosteroid injections for cervicogenic headache after a whiplash injury (128). Controlled studies have failed to demonstrate such efficacy although the studies had various design flaws (Table 68-5), including the use of saline as a placebo, patient selection bias without using a double block technique, and injection in isolation of other treatments. Selection of patients without using the double block paradigm may potentially include those patients with false-positive results. Finally, injection is not recommended to be used in isolation of other treatments. Rather, when tolerable, patients should be involved in a directed therapy program if they experience significant pain reduction (therapeutic window) after the injection.

A recently published systematic review of the literature from 2004 to 2006 has demonstrated strong evidence for diagnostic injections in the cervical and lumbar spine and moderate evidence for diagnostic injections in the thoracic spine (115). Another published review from 2007 has noted “limited” evidence for intra-articular cervical facet joint injections and “moderate” evidence for intra-articular lumbar Z-joint injections for pain relief (129). It is interesting to note, however, that this study did conclude that there actually was moderate evidence for short-and long-term pain relief from medial branch blocks.

Complications

Potential complications of fluoroscopic-guided, contrastenhanced lumbar Z-joint injections or medial branch blocks are rare. The most common post-procedural problem is transient pain at the injection site. However, there have been rare case reports of meningitis, inadvertent spinal anesthesia, and infection after Z-joint injections (137,138). Recurrent back and neck pain after radiofrequency neurotomy may be due to incomplete ablation or medial branch regeneration (139). Since the dorsal root ganglia are left intact, the ablated medial branches may regenerate. Because radio frequency neurotomy does not permanently denervate the Z-joints or cause inherent instability in the spine, the concern of Charcot facet joint development has little ground and no such cases have been published (140). Also, because the DRG remains intact, deafferentation pain should not occur. Side effects from radiofrequency neurotomy are rare when the procedure is performed correctly but include local pain and infection.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Diagnostic Nerve Root Block

Because of the overlap pattern of dermatomal innervation and the anatomic variants of spinal nerves, clinical history and physical examination alone are often not sufficient to accurately diagnose the segmental level of a spinal nerve lesion. In addition, current imaging studies and electrodiagnostic tests have limited sensitivity and specificity in reaching a conclusive diagnosis of radicular pain at a specific spinal level. Therefore, a diagnostic SNRB can be an important test with respect to providing a physiologic diagnosis of the level of radicular pain. By selectively depositing a limited volume of local anesthetic directly around the spinal nerve rather than in the epidural space, pain relief after the SNRB identifies the spinal nerve blocked as the involved level. A diagnostic SNRB is indicated when imaging and/or electrodiagnostic testing studies are not corroborative with the clinical findings, or these tests demonstrate multilevel pathology and the exact pain generators are unclear. Studies reveal that a diagnostic SNRB is 87% to 100% accurate when intraoperative findings are used as the gold standard (77–79). Surgery performed at the positive SNRB level had higher success rate than surgery done at a level with a negative SNRB in the lumbar spine (80). In the cervical spine, SNRB also helped guide with a high level of success the evaluation of radicular pain in the multilevel degenerative cervical spine and subsequent surgery (91).

A diagnostic SNRB is performed with the needle tip directed to the posterior lateral portion of the neuroforamen, as for a transforaminal ESI. However, for a selective spinal nerve block, the needle tip should remain outside the neuroforamen pointing at the 5 o’clock position of the pedicle above for a left-sided SNRB or at 7 o’clock for a right-sided SNRB. The needle tip should also be localized immediately lateral to the superior articular process. Special care should, therefore, be exercised not to impale or transfix the exiting spinal nerve and it is contraindicated to inject steroid or local anesthetics directly into a spinal nerve due to their neurotoxic effects. The patients should be examined before the injection to document the maneuvers and activities that produce radicular pain. The same provocative maneuvers or activities should be repeated for comparison after the diagnostic injection. Selective spinal nerve block as a diagnostic procedure is considered positive when the patient’s radicular symptoms are reproduced upon gentle needle contact with the nerve sheath, followed by relief of the radicular pain after diagnostic blockade with local anesthetic.

Despite the apparent advantages of diagnostic selective spinal nerve block, the test has several limitations. Because of the overlap of the dermatomal distribution, blockade of one segment will not necessary produce clear-cut sensory changes. Second, because the anesthetic blockade is placed at the spinal nerve, a successful block can impede pain transmission not only from the spinal nerve but also from sites distal to the spinal nerve. Furthermore, the specificity of the blockade also depends on the spread of the injectate and the exact location of the needle tip. One study demonstrated that 1 mL of injected contrast in an L4 SNRB spread onto the L5 nerve root in 46.1%, and 1 mL of injected contrast in an L5 SNRB spread onto an S1 nerve root in 57.7% of subjects (92). If the needle tip is placed too close to the neuroforamen, even 0.5 mL of injectate can spread to the adjacent nerve root level through the neuroforamen, thus compromising the specificity of the segmental test (Fig. 68-11). However, the efficacy of blockade with anesthetic less than 0.5 mL is questionable. A study that utilized multi-slice computed tomography (CT) revealed that only 0.6 mL of injectate with contrast during cervical TEIs could be accepted as being selective enough for diagnostic investigations (93). It appears that a volume somewhere between 0.5 and 1 mL of local anesthetic should be used in performing an SNRB. More randomized, controlled studies are needed to determine the optimal volume of injectate for a diagnostic selective spinal nerve block and to ascertain the true value of a diagnostic SNRB in aiding with the selection of appropriate patients for spinal decompression surgery.

FIGURE 68-11. Right L5 TEI. Injecting 0.5 mL of contrast outlined the right L5 spinal nerve. However, contrast also spread through the epidural space and outlined the right S1 nerve root as well.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Fluoroscopic guidance and contrast enhancement are essential for accuracy when performing epidural injections (43). Published data show that even in experienced hands, epidural injections without fluoroscopic and contrast-enhanced guidance (i.e., “blind injections”) often result in inaccurate placement (Table 68-3) (43). These misplacements include the needle being inadvertently positioned into the subarachnoid, intravascular (Table 68-4), or subcutaneous regions (caudal approach) or fascial plane superficial to the ligamentum flavum for interlaminar ESI. Misplacement into the subarachnoid or intravascular regions has major potential safety implications, particularly for those injections that include local anesthetics as part of the injectate. Use of detection of flash back of blood in the needle hub to gauge the intravascular placement of needle is not a reliable substitute for looking for a vascular pattern after contrast injection (44). Although injection accuracy should also logically affect efficacy, there is very limited data on the efficacy of fluoroscopic-guided ESIs compared with blind ones. One such study demonstrated that fluoroscopic- guided transforaminal ESIs provided better pain relief than blind interlaminar ESIs (45). ESIs using fluoroscopic guidance have also been shown to reduce procedure-related complications compared to non–image-guided injections (46–48).

As a result of these factors, it is recommended that ESIs be performed under fluoroscopic guidance and with radiographic contrast, documenting appropriate needle placement in order to improve their accuracy, and by extension their safety and efficacy (49).

Efficacy of Epidural Injections

Recent studies have demonstrated good efficacy of lumbar ESIs when proper needle placement is confirmed by using fluoroscopic guidance and radiographic contrast (50,51). A meta-analysis of 12 published randomized controlled trials concluded that ESIs are effective (52). In a systematic review of randomized trials on lumbar epidural injections, Abdi et al. concluded that there was moderate evidence that caudal and TEIs are effective in providing long-term (>6 weeks) pain relief and limited evidence for the effectiveness of lumbar interlaminar ESIs (30). Other studies have suggested that 60% to 75% of patients receive some relief after ESIs (53,54). Benefits include relief of radicular pain and low back pain (generally relieving leg pain more than back pain), improved quality of life, reduction of analgesic consumption, improved maintenance of work status, and a decreased need for hospitalization and surgery in many patients (27,50–56). One study showed no difference in analgesic use in patients with sciatica who had received three ESIs (58). Another study reported that patients were more likely to start taking opioids and more likely to receive surgery after receiving multiple (>3) injections than patients receiving fewer injections (59). However, the population of patients receiving multiple steroid injections was more likely to have had more advanced disease such as spinal stenosis. A prospective cohort study was conducted on cervical TEIs for both neck pain and radicular pain from herniated discs or spondylosis. Twenty-one such patients awaiting surgery received cervical TESIs 2 times, at 2-week interval with 12 months follow-up. All patients had reduction in neck and radicular pain, and five of these patients cancelled the surgery (59). In contrast, a prospective randomized study involving 20 patients with cervical radicular pain confirmed by selective nerve root block (SNRB) and with magnetic resonance imaging (MRI) evidence of corresponding segmental pathology demonstrated that there was no difference in radicular pain reduction between steroid/local anesthetic and saline/local anesthetic groups at 3-week follow-up (60). A limitation of this study, however, was that it only involved small numbers of patients and that it is unknown whether saline/local anesthetic is a true control.

There are more studies in support of ESIs for low back pain (7,8,42,53–55) than there are negative studies (56). Problems with some of these supportive studies, however, include the fact that most of these studies did not use fluoroscopy and radiographic contrast to document accurate placement of the injected substance into the epidural space. Furthermore, many of these injections were not performed at the presumed level of pathology, even though this has been demonstrated to be critical to the success of ESIs (61). These methodologic problems are likely contributing factors to the mixed assessment that ESIs have received. A review of six prospective randomized clinical trials of fluoroscopic-guided transforaminal ESIs, selective nerve blocks, or periradicular nerve injections concluded that there is moderate (level III) evidence that TESIs are safe and effective in reducing radicular pain. However, more prospective, randomized, placebo-controlled studies using sham procedures are needed to provide more conclusive evidence for the efficacy of TESIs in treating lumbar radicular symptoms (62). A recent review article concluded that with proper patient selection, ESIs are a reasonable alternative to surgery for short-term pain relief, reduced medication use, and increased patient activities while awaiting natural recovery (63).

Aside from technical considerations, response to ESIs has been shown to be related to several other factors such as the type and quantity of steroid preparation used, volume of injectate, underlying pathophysiology, and the duration of symptoms (23,26,28). In general, radicular pain or radiculopathy induced by herniated nucleus pulposus appears to respond better to corticosteroid injection than that induced by spinal stenosis. There is essentially no literature that correlates the type of disc herniation with the response of ESIs. It is the authors’ collective experience and observations that patients with large lumbar disc herniations obliterating the neuroforamen or extraforaminal herniations often have less benefit from ESIs. One study demonstrated that radiculopathy induced by the combination of spinal stenosis and disc herniation has less favorable outcome with ESI. In lumbar spinal stenosis, the efficacy of ESI correlated with the degrees and the levels of stenosis categorized by MRI (64). Patients with single-level lumbar spinal stenosis generally respond better than those with multilevel lumbar spinal stenosis. ESIs provide better efficacy in reducing pain and opioid consumption for patients with mild to moderate rather than severe stenosis. But a prospective cohort study with 12-month follow-up in patients with severe degenerative lumbar spinal stenosis found that fluoroscopicguided and contrast-enhanced caudal ESIs reduced bilateral radicular pain and improved standing and walking tolerance (65). In contrast to radiculopathy due to herniated discs and/ or spinal stenosis, radiculopathy caused by epidural scar tissues or trauma such as nerve root stretch injury often responds poorly to ESI.

A recent prospective, randomized study on lumbar TESIs demonstrated positive efficacy in treating radicular low back pain. The success rate for TESI is 84%, compared to 48% with trigger point injection, at 1.4 years of follow-up (66). Another prospective, randomized controlled clinical trial compared perineural (transforaminal) epidural injection with conventional posterior (interlaminar) epidural injection with steroid, and perivertebral injection with local anesthetic as a control group (27). The result demonstrated that perineural injection was the most effective approach. Both perineural and conventional epidural injection with steroid were better than that with saline alone (27).

Uncontrolled studies have generally reported favorable outcome of cervical epidural injections for cervical radiculopathy with structural abnormalities such as cervical disc herniation (66,67) and spondylosis (68). However, the prospective, randomized, blinded and controlled clinical trials on the outcome of cervical and thoracic epidural injections have not been reported yet in the peer-reviewed literature. At the time of this writing, there have been no prospective randomized trials on thoracic ESIs that have been published in the peer-reviewed literature.

Patients should be educated that ESI alone may not be the only solution to give them long-term benefits. ESI is just one of many nonoperative treatments used to treat low back pain or radicular symptoms. Other treatments may include shortterm bed rest; medications (e.g., analgesics, muscle relaxants); a properly designed program of physical therapy; and management of any psychological, financial, marital, and work-related problems. A comprehensive treatment approach is likely to produce better outcomes for patients with low back pain than any single modality used in isolation (23,26,51). Recently published research on the outcome of ESIs has supported this notion of multifaceted treatment (50,69).

Recent Advances and Investigations on the Management of Radicular Pain

A study was performed on lumbar TEIs for radiculopathy using autologous conditioned serum (ACS) containing enriched IL-1 antagonist. The ACS group showed statistical superiority over both triamcinolone groups (5 and 10 mg) with regard to the VAS score for pain from week 12 to the final evaluation at week 22, statistical superiority at week 22 compared to the triamcinolone 5 mg group, and no significant difference compared to the 10 mg triamcinolone group. This is an exciting finding, as autologous blood is not associated with the same side effect concerns associated with corticosteroids, and theoretically can be used more frequently than corticosteroids. Additional studies are needed to confirm this finding (70).

An animal study examined the potential benefits from anti-TNF-[α] therapy in reducing neurotoxic effects induced by the nucleus pulposus on neuronal tissues (71). Two openlabel human clinical trials, one using intravenous infliximab (a monoclonal antibody against TNF-[α]) and the other using (etanercept) a soluble TNF-[α] receptor antagonist, in patients with sciatica from disc herniation demonstrated significant efficacy in pain reduction (72,73). Although these basic science and human studies initially implied potential clinical use of anti-TNF-α medication as a treatment for patients with radiculopathy due to disc herniation, there were disappointing long-term findings related to the evaluation of the efficacy of an anti-TNF-[α] treatment versus a placebo injection in disc herniation-induced sciatica in a randomized controlled setting. Specifically, 3-month results showed no difference in the patient-reported symptoms or in the more objective outcomes (SLR, days on sick leave, discectomies) between intravenous infliximab 5 mg/kg and placebo (74). The 1-year results also confirmed the earlier findings (75). Clearly, further studies using multiple intravenous infusion of the anti-TNF-α agents or epidural injection of the similar substances are necessary to clarify any efficacy of anti-TNF-α treatment in radicular pain.

Safety and Complications of Epidural Injections

A retrospective cohort study reviewing the immediate complications of 2,217 patients who received selective lumbar nerve root blocks under fluoroscope, reported a 5.5% minor complication rate (76). When performed by a skilled, experienced clinician within an appropriate setting and on carefully selected patients, the chance of a significant complication from an ESI is remote (23,25,26,77–83). Like any procedure that punctures the skin, bleeding and soft tissue infection are potential but rare risks. More common risks of epidural injection are acute back pain, postural puncture headache (0.5% to 1% for lumbar interlaminar and 0.6% for caudal epidural injections), nausea, vomiting, dizziness, vasovagal reactions, and epidural hematoma (0.001%) (23,25,26,29). Nerve root injury, arachnoiditis, and meningitis also have been reported but are very rare. Lumbar transforaminal and caudal epidural injections were associated with 9.6% and 15.6% of minor complications, respectively (82,83). Anterior spinal cord syndrome has been reported after lumbar transforaminal ESIs, presumably due to inadvertent needle contact with, or local anesthetics induced spasm of, the artery of Adamkiewvicz. Although the artery of Adamkiewvicz is usually located on the left side from T9 to the L3 segments, anterior cord syndrome has been reported in transforaminal ESI as low as the S1 level. Other possible mechanism of spinal cord injury related to ESIs include embolism of the injected corticosteroid particles causing spinal cord ischemia. Although rare, spinal cord injuries have been reported due to cervical and thoracic epidural injections from direct needle trauma, presumed radicular artery spasm, or steroid particle embolization (84–87). Therefore, transforaminal ESIs, especially cervical TEIs, should be performed by the most skilled and highly experienced injectionists. Real-time fluoroscopic imaging during contrast injection should be employed. Digital subtraction angiography may provide an additional safety margin for the prevention of inadvertent intra-arterial injection. Dexamethasone should be chosen as the steroid for transforaminal ESIs due to its small particle size among the various corticosteroid preparations. A recent study has demonstrated that dexamethasone and the larger particulate-sized methylprednisolone (88) have essentially the same efficacy in cervical epidural injections (89).

Corticosteroid-induced adrenal insufficiency has been reported. For example, mild hypothalamic-pituitary-adrenal (HPA) axis suppression has been reported from 1 to 3 months after receiving a total of three ESIs (once weekly) with 80 mg of triamcinolone (Aristocort) in 7 mL of 1% lidocaine (90).

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Caudal lumbar epidural injections are performed by inserting a needle through the sacral hiatus into the epidural space at the sacral canal (Figs. 68-9 and 68-10). The patient is placed in a prone position. The legs are slightly abducted and feet turned inward to separate the gluteal fold to facilitate palpation of the sacral cornu. The sacral skin is prepped and draped in a sterile manner. AP imaging can be used to visualize the location of the sacral hiatus. Alternatively, lateral imaging is used to view the bone defect, consistent with the opening of the sacral hiatus. The skin and the tissues overlying the sacral hiatus are anesthetized with 1% lidocaine. A 22- or 25-gauge spinal needle of appropriate length or a Tuohy epidural needle is inserted into the sacral hiatus. Loss of resistance can sometimes be felt upon needle penetration through the sacral ligament. Several milliliters of the contrast are injected in order to produce a sacral epidurogram to note the level that the contrast reaches. In the lateral view, a typical epidural contrast spread within the sacral canal resembles “smoke up a chimney” (Fig. 68-9), and in the AP view, it often looks like a “Christmas Tree” (Fig. 68-11). If a vascular pattern is observed, the needle should be withdrawn and redirected. Upon proper positioning, a mixture of 10 to 20 mL of solution containing 80 to 125 mg of preservative-free methylprednisolone or other equivalent doses of corticosteroid, preservative-free normal saline, and preservative-free 1% lidocaine is slowly injected into the epidural space through the spinal or epidural needle.

FIGURE 68-9. Caudal epidural injection. Needle tip in the sacral canal. Note the “smoke up the chimney” pattern of contrast in the epidural space of the sacral canal.

FIGURE 68-10. Caudal epidural injection. AP view demonstrating contrast in a “Christmas tree” pattern within the epidural space.

FIGURE 68-11. Right L5 TEI. Injecting 0.5 mL of contrast outlined the right L5 spinal nerve. However, contrast also spread through the epidural space and outlined the right S1 nerve root as well.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Comment

In one systematic review comparing transforaminal, interlaminar, and caudal ESIs, the authors concluded that there was moderate evidence for long-term (>6 weeks) relief of lumbar radicular pain using the transforaminal and caudal approaches, but limited evidence using the interlaminar approach (30). The authors also concluded that there was moderate evidence for relief of cervical nerve root pain using both the transforaminal and interlaminar approaches (30). Another study concluded that the transforaminal approach was more effective than the interlaminar or caudal approaches in treating lumbar pain (31). A review showed transforaminal lumbar ESIs under fluoroscopic guidance to be more cost effective than blind interlaminar and caudal ESIs (32).

As of this writing, no peer-reviewed, randomized controlled studies have compared transforaminal and interlaminar ESIs in the thoracic region.

Technique

For lumbar transforaminal epidural injection (TEI), the patient is placed in a prone position with a pillow or abdominal roll under the abdomen to at least reduce and ideally reverse the lumbar lordosis in order to open up the foramen. Using an ipsilateral oblique fluoroscopic view, the x-ray tube (source) of the C-arm fluoroscope is generally angulated in either a caudal direction (for L5-S1 and L4-5 TEI) or cephalic direction (for L3-4 and above TEI) to square the inferior endplate of the vertebral body, and to place the superior articular process of the subjacent segment pointing at 6 o’clock of the pedicle of the above level that appears as a Scottie dog eye. Local skin is then prepped and draped in a sterile manner. A local skin wheel is raised with 1% lidocaine at the needle entry site and the subcutaneous tissue in the needle trajectory path is infiltrated with 1% lidocaine. A 22- or 25-gauge spinal needle of appropriate length is inserted and directed down and parallel to the fluoroscopic beam toward the “safe triangle.” The safe triangle is formed by the lower border of the pedicle, the lateral margin of the vertebral body, and the traversing nerve root. To avoid deep needle placement and potential injury to the vasculature or nerve root or DRG in the neuroforamen, the novice injectionist should advance the needle until the needle tip touches the lower edge of the Scottie dog eye, the junction of the transverse process and the superior articular process. The needle is then slightly withdrawn for 2 to 3 mm and redirected inferiorly just under the lower edge of the transverse process for about 0.5 mm. Further advancement of the needle should be under AP and cross table (lateral) views. The final needle tip position should be at the posterior half of the neuroforamen just under the pedicle in the lateral view to minimize the potential injury to the vasculature, nerve root, or DRG. In the AP view, the needle tip should not be medial to the medial edge of the pedicle to avoid penetrating the dura mater. For S1 transforaminal injections, the eye of the Scottie dog can also be used as an injection landmark. Using a slightly caudad and ipsilateral fluoroscopic view, the S1 Scottie dog image is outlined. The needle should be directed to the outer upper quadrant of the neuroforamen. In the lateral view, the needle tip should not pass the anterior margin of the sacral canal that appears as a radiological lucent strip. A neurogram pattern should then be visualized under an AP view (Fig. 68-4).

FIGURE 68-4. Left L5-S1 TEI. AP view showing a neurogram pattern of left S1 and L5 nerve roots.

For the L5-S1 foramen, the C-arm source often needs to be tilted in a caudad direction to accommodate any remaining lumbar lordosis. An ipsilateral oblique projection is then used to visualize the Scottie dog and the target is identified as the region immediately under the pedicle, slightly lateral to the 6 o’clock position (Fig. 68-5). This position leads to needle placement in the neuroforamen, ventral to the nerve root. Lateral imaging is used to demonstrate the needle depth, which should be located at the superior portion of the intervertebral foramen, just under the pedicle (Fig. 68-6). An AP view is then obtained to ensure that the needle tip is located at the “safe triangle,” slightly lateral to the 6 o’clock position of the pedicle. The safe triangle is formed by the lower border of the pedicle, the lateral margin of the vertebral body, and the traversing nerve root. A needle position located within the safe triangle and lateral to the 6 o’clock position is deemed safe because it will not penetrate the nerve, blood vessels, or dura mater. Nevertheless, because of the precarious location of the nerve root and the DRG, caution should be exercised by advancing the needle slowly upon entering the neuroforamen, to avoid needle penetration of these neurologic structures. If the patient complains of radicular pain or paresthesias, the needle should be withdrawn and redirected superiorly. Once the needle is deemed at the proper position, approximately 1.0 mL of the contrast is injected under live fluoroscopic view. The needle should be redirected if there is vascular uptake of the contrast. The injected contrast should ideally outline the nerve root and also show epidural spread. Three milliliters of a mixture of solution containing 40 to 125 mg of preservative-free methylprednisolone, 6 to 9 mg of preservative-free betamethasone sodium phosphate, 40 to 50 preservative-free triamcinolone (33,34), or other equivalent dose of preservative-free corticosteroid and preservative-free 1% lidocaine can be slowly injected into the neuroforamen through the spinal needle (25,26).

FIGURE 68-5. L5-S1 and S1 TEI. Oblique view showing needle just under the 6 o’clock position of the L5 pedicle and outer lateral quadrant of S1 for L5 and S1 TEIs respectively.

FIGURE 68-6. Lumbar L5-S1 and S1 TEIs. Lateral view demonstrating contrast in the ventral epidural space. Theoretically, the transforaminal approach should achieve more anterior flow of the injectate than would be typical for an interlaminar approach.

A thoracic TEI is performed with the patient in a prone position. The fluoroscope should be directed in a similar fashion as for lumbar TEI. A critical part of the injection is the correct identification of a clear rectangular-shaped clear space window under the fluoroscope. The upper and lower borders of the rectangle are the lower edge of the lamina of the same vertebral segment and the upper edge of the inferior vertebral endplate of the same segment. The lateral and medial borders of the rectangle are the medial edge of the rib head and the pars interarticularis of the same segment, respectively. After proper skin preparation and local anesthesia, the spinal needle is inserted and directed toward the lower edge of the Scottie dog eye using the same technique as in the lumbar TEI. Caution should be exercised not to direct the needle outside the clear rectangle window. If the needle strays too far laterally outside the rectangular window, it can penetrate the pleura, resulting in a pneumothorax. Needle placement too medially outside the rectangular window can result in spinal cord injury. The final needle position should be in the posterior half of the neuroforamen in the lateral view and the 6 o’clock position of the pedicle in an AP view. The contrast and corticosteroid are injected in a similar fashion as when performing a lumbar TEI.

A cervical TEI is performed, with the patient in a supine position and the head turned to the contralateral side. A peripheral intravenous line should be placed, and vital signs, as well as oxygen saturation, should be monitored. The C-arm fluoroscope is rotated ipsilaterally and angulated either cephalically or caudally to maximally visualize the targeted neuroforamen (Fig. 68-7). After aseptic skin preparation and draping, the skin entry site is anesthetized with 1% lidocaine. A 22- or 25-gauge, 3.5-in. spinal needle is then inserted at the injection site and directed down and parallel to the fluoroscopy beam until the needle contacts the superior articular process forming the posterior wall of the neuroforamen. At this point, the needle tip is withdrawn and directed slightly anteriorly to “walk off ” the superior articular process and slip into the neuroforamen. The C-arm is turned to the AP view to assess the needle depth. The needle should be advanced in millimeter-by-millimeter increments in the AP view to ensure that the needle is not advanced past the center of the lateral mass (Fig. 68-8). Overzealous advancement of the needle into the inner half of the lateral mass can potentially lead to penetration of the dura into the subarachnoid space or into the spinal cord. The desired final needle location is the posterior wall of the targeted neuroforamen in the oblique view and the lateral half of the lateral mass in the AP view. After negative aspiration of the cerebrospinal fluid (CSF) or blood, 0.5 to 1 mL of contrast is injected under real-time imaging to exclude a vascular pattern. The needle should be repositioned if there is either blood flashback in the needle hub or a vascular pattern upon contrast injection. If the patient complains of paresthesias or radicular pain, the needle also needs to be repositioned. With satisfactory needle position, the injected nonionic water soluble contrast often outlines the exiting spinal nerve and fills the neuroforamen with epidural spreading or an epidurogram. After the satisfactory position, 1.0 mL of a test dose of 1% lidocaine is injected, and the patient is monitored for 2 minutes for any changes in vital signs or consciousness or neurological deficits in the extremities that would indicate an intravascular injection. For patients without abnormal signs, 40 mg of methylprednisolone, 6 mg of betamethasone sodium phosphate, or 10.25 mg of nonparticulate dexamethasone in a total volume of less than 2 mL per neuroforamen may then be injected (25,26,35). To prevent inadvertent arterial embolism into the spinal cord and brain stem, a nonparticulate soluble corticosteroid such as dexamethasone is recommended for cervical transforaminal ESI.

FIGURE 68-7. Oblique view of transforaminal cervical epidural injections showing needles in the posterior walls of the C4/5 and C5/6 neuroforamina.

FIGURE 68-8. AP view of transforaminal cervical epidural injection demonstrating left C6 neurogram.

Refferences

Source:  Physical Medicine and Rehabilitation - Principles and Practice

Technique

The patient is placed in a prone position, ideally with a pillow or abdominal roll under the abdomen to help open up the lumbar interlaminar space by reversing the lumbar lordosis. The skin is then prepped and draped in a sterile manner. The targeted interlaminar space is identified using an anteroposterior (AP) fluoroscopic view, the vertebral body endplates at the targeted level are “squared off ” by adjusting the relative cephalad-caudad orientation of the fluoroscope, and the fluoroscope position is further adjusted so that the proposed needle entry site into the epidural space is centered with respect to the fluoroscopic view in order to reduce parallax error. After the local skin and underlying tissues are anesthetized with 1% lidocaine, a 17- or 20-gauge epidural needle (e.g., Tuohy or Crawford) of appropriate length, depending upon body habitus, is inserted at the injection site. The epidural needle then penetrates the skin, subcutaneous tissue, paraspinal muscles (paramedian approach) or the interspinous ligament (midline approach), and ligamentum flavum, where increased resistance is usually felt. At this point, the needle stylet is removed and the epidural needle is connected, ideally via extension tubing, to a Luer-Lok low friction glass or plastic syringe filled with about 2 mL of preservative-free saline. (Although the syringe can alternatively be filled with air, this can theoretically lead to an air embolus with inadvertent intrathecal injection and is believed to cause a higher incidence of postepidural headaches.) As the operator’s one hand advances the needle slowly into the ligamentum flavum, the other hand exerts steady gentle pressure on the plunger of the syringe. Depending upon the experience of the injectionist and the patient’s body habitus, the entire procedure can either be done using an AP view, or additional lateral views can also be obtained to help judge the depth of penetration. Once the needle penetrates the ligamentum flavum, loss of resistance should be detected by the hand holding the Luer- Lok syringe because saline will be suddenly injected owing to the negative pressure within the epidural space. Aspiration is then performed to ensure no CSF or blood return. (If blood is present, the needle position should be readjusted until no blood return is found. If CSF return is present, the needle is either withdrawn and the procedure attempted at an adjacent level or a caudal or transforaminal approach considered for the epidural.) A small amount of contrast (usually in the range of up to several milliliters) is then injected to visualize an epidurogram pattern that can be described as a Christmas tree, a bunch of grapes, or a vacuolated pattern (Fig. 68-1). Two other contrast patterns are possible if there has been false loss of resistance (in which the needle has not yet penetrated into the epidural space) or accidental needle penetration through the subarachnoid membrane. In these cases, contrast pattern recognition is essential. For example, in situations of false loss of resistance, the injected contrast typically appears as a local accumulation of contrast, whereas a typical myelogram revealing a relatively tubular (column-shaped) contrast pattern is generated when there has been subarachnoid membrane penetration. In the latter situation, the needle should be withdrawn, and the injection can be reattempted at an adjacent interlaminar space or by switching to a caudal or transforaminal approach. Once the needle is confirmed in the epidural space and no vascular pattern is observed upon contrast injection, a mixture of 4 to 10 mL of solution containing 80 to 125 mg of preservative-free methylprednisolone or 12 mg of preservative-free betamethasone sodium phosphate (Celestone Soluspan) and preservative-free 1% lidocaine with or without saline is injected into the epidural space through the epidural needle.

FIGURE 68-1. Lumbar interlaminar epidural injection. AP view showing a typical vacuolated epidurogram.

Several procedural modifications are recommended for cervical or thoracic interlaminar epidural injections due to the presence of the underlying spinal cord. For example, the cervical or thoracic interlaminar epidural injections should not be performed at the level of herniated nucleus pulposus or spinal stenosis, to avoid further potential spinal canal compromise and spinal cord compression. Furthermore, consideration should be given to directing the needle so that it contacts the inferior aspect of the lamina, to provide a clearly felt sense of depth prior to engaging the ligamentum flavum. The needle is then withdrawn slightly and directed into the ligamentum flavum. Further needle advancement should be performed using a lateral view and in addition to using the loss-of-resistance technique, the needle tip should not be advanced further than the laminar line to avoid the potential penetration of the dura mater or spinal cord injury. Epidural dye pattern recognition should be performed after a minimal amount of contrast has been injected since a total volume of less than 4 mL is recommended in these body regions (Figs. 68-2 and 68-3).

FIGURE 68-2. AP view of cervical interlaminar epidural injection demonstrating typical “honeycomb” pattern of epidurogram.

FIGURE 68-3. AP view of thoracic interlaminar epidural injection at the T10-11 level. Note the angle of the needle relative to the axis of the spine.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
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