ORIGINAL ARTICLE
Analysis of Inadvertent Intradiscal and Intravascular Injection During Lumbar Transforaminal Epidural Steroid Injections A Prospective Study Ji H. Hong, MD, PhD,* Sae Y. Kim, MD,* Billy Huh, MD, PhD,† and Hyun H. Shin, MD* Background and Objectives: Inadvertent intradiscal injection during a lumbar transforaminal epidural steroid injection (TFESI) can be critical given the possibility of discitis and disc degeneration. Intravascular steroid injection can result in devastating neurologic complications. We sought to identify the incidence of intradiscal and intravascular injection during lumbar TFESI and determine whether an aspiration test and static fluoroscopic image can be used to predict intravascular needle placement. Methods: We evaluated 251 TFESIs in 219 patients. All TFESIs were performed by one of the authors using classic TFESI technique. After final needle position was confirmed using biplanar fluoroscopy, 1 mL of contrast was injected after negative blood or cerebrospinal fluid aspiration. Using static and real-time fluoroscopy, we assessed the incidences of intradiscal injection, blood flashback, and the presence of intravascular contrast spread. Results: The incidence of intradiscal injections was 2.3% (6/251). Six intradiscal injections were observed, all among patients who had not previously undergone disc surgery. Five intradiscal injections occurred at the L4-5 level and 1 at the L5-S1 level. The incidence of overall intravascular injection was 15.5% (39/251), of which the incidence of simultaneous vascular and epidural injection was 12.7% (32/251), whereas intravascular injection only was 2.8% (7/251). The sensitivities for detecting intravascular access via aspiration or static fluoroscopic image with contrast were 20.5% and 51.2%, respectively. Conclusions: Inadvertent intradiscal injection during TFESI is not rare. Physicians who perform interventional pain procedures should increase their awareness of related potential complications. The aspiration test and static image of fluoroscope often fail to detect the intravascular injection during the TFESI. Real-time fluoroscopy should be the gold standard for confirming intravascular injection. (Reg Anesth Pain Med 2013;38: 520–525)
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umbar epidural steroid injection is one of the most frequently performed interventional pain management procedures for lumbar radiculopathy. The transforaminal, interlaminar, and caudal routes are 3 techniques available to access and deliver medication to the epidural space.1,2 Transforaminal epidural steroid injection (TFESI) can be carried out using either the classic or
From the *Department of Anesthesiology and Pain Medicine, Keimyung University Dong San Hospital, School of Medicine, Daegu, Korea; and †Department of Anesthesiology and Pain Medicine, Duke University Medical Center, Durham, NC. Accepted for publication July 31, 2013. Address correspondence to: Ji H. Hong, MD, PhD, Department of Anesthesiology and Pain Medicine, Keimyung University Dong San Hospital, 56 Dal-Sung Ro, Jung gu, Daegu 700-712, Korea (e‐mail: [email protected]). The authors declare no conflict of interest. This study was supported by BISA research funds from Keimyung University in 2010. This study was approved by the institutional review board of Keimyung University Dong San Hospital (IRB No 12-88). Copyright © 2013 by American Society of Regional Anesthesia and Pain Medicine ISSN: 1098-7339 DOI: 10.1097/AAP.0000000000000010
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retrodiscal approach. The classic technique targets the inferior aspect of the midsagittal bisector in the anteroposterior (AP) fluoroscopic view (6-o’clock position) of the pedicle, with the final needle position in the superior dorsal or ventral aspect of the intervertebral foramen on the lateral fluoroscopic view.3 The needle tip target for the retrodiscal technique is the inferior ventral region of intervertebral foramen on the lateral fluoroscopic view, just posterior to the annulus of the disc and posterior longitudinal ligament.4,5 According to the report by Murthy et al,5 the artery of Adamkiewicz was overwhelmingly located in the superior aspect of the neural foramen; therefore, they suggested that epidural needle placement at L3 and above needs to be directed to an inferior and slightly posterior position within the foramen. Due to the purported advantage of the delivery of high concentration of medication to the ventral epidural space,1,2 pain physicians commonly perform transforaminal injections of steroids, yet the procedure is not without risk.6 Recently, there have been several case reports6–9 and 2 retrospective studies10,11 regarding the incidence of intradiscal injection during TFESI. These reports10,11 suggest an incidence of intradiscal injection as low as 0.25% and 0.17%. In our clinical practices, however, we encounter inadvertent intradiscal injection not infrequently; therefore, we questioned the reported low incidence. The risk of discitis, with potentially significant morbidity, mandates a technique that limits this complication.12 We hypothesized that with a prospective study design we would encounter intradiscal injection during TFESI more commonly than previously reported. Several reports have documented serious complications associated with the lumbosacral epidural injection, including paraplegia and spinal cord infarction with irreversible neurologic outcomes.13–15 Many of these adverse outcomes are thought to be secondary to intravascular injection/embolization of corticosteroid particulates via the radicular arteries. It has been suggested that the confirmation of intravascular injection during TFESI should be assessed under the guidance of real-time fluoroscopy,16–18 and the use of digital subtraction angiography (DSA).19,20 The incidence of intravascular injection has been reported to be 8.5% to 13.1% of fluoroscopically guided lumbar TFESI depending on the level of injection.21–23 The commonly used method of contrast injection after an aspiration test has a low sensitivity for identifying intravascular injection (34.1%–45.9%),16,17,21 and epidural injections performed under static image guidance often fail to detect intravascular injection (57%–59.1%).16,18 The aim of the current study was to identify the incidence of both intradiscal and intravascular injection in TFESI, using static and real-time image guidance.
METHODS This study was approved by the ethics committee of our institution, and written informed consent was obtained from all patients after explaining the risks, benefits, and goals of the study.
Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
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Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
Intradiscal Incidence During TFESI
FIGURE 1. Anteroposterior (A) and lateral (B) fluoroscopic image of the final needle position for TFESIs.
Data were collected on the patients’ age, sex, type of disease, intradiscal dye appearance, presence of vascular spread of contrast on static, real-time fluoroscopic images, blood flashback, and spinal level where TFESI were performed. We hypothesized that the probability of intradiscal and vascular injections of contrast was 2% and 15%, respectively, based on the review of related articles6–11,16,17,21–23 and the results of our preliminary study. On the basis of an α error level of 0.05, a β error level of 0.2, and a 2-sided test, 234 injections were required as a total sample size with an 80% power. All statistical analyses were performed using SPSS version 17 (IBM, Chicago, Illinois). A χ2 test was used to compare categorical variables. From September 2010 to July 2011, 219 consecutive patients were enrolled and received 251 fluoroscopically guided TFESI using the classic technique. Thirty-two patients received 2-level TFESI, and the remaining 187 patients received 1-level TFESI. Inclusion criteria were patients with radicular pain from spinal stenosis, herniated nucleus pulposus, internal disc disruption, or failed back surgery syndrome. Exclusion criteria were patients who had known allergies to contrast or local anesthetics or who had experienced coagulopathy. Patients who received either interlaminar or caudal epidural injections were excluded. All TFESI were performed by an interventional pain specialist (J.H.H.) with more than 7-year experience in image-guided injections. Using the classic approach for TFESI as described previously, the injection target was the midsagittal bisector (“6-o’clock
position”) of the pedicle in the AP projection. After marking the skin entry point under image guidance, the skin was prepared and draped in a sterile fashion. The C-arm was rotated obliquely to ensure injection at the neural foramen. The skin entry site was infiltrated with 1% lidocaine, and 23-gauge Quincke type spinal needle was advanced along the axis of the x-ray beam toward the 6-o’clock position of the pedicle, avoiding the segmental nerve and intervertebral disc. Lateral radiographic imaging was also used while advancing toward the intervertebral foramen and superolateral to the exiting spinal nerve with a special attention to minimize the risk of disc puncture. The final needle position was confirmed with AP and lateral fluoroscopic views, and the needle tip location was confirmed at the superior ventral aspect of the neural foramen on the lateral view (Fig. 1A, B). Up to 3 mL of contrast dye (Omnipaque 300; GE Healthcare, Little Chalfont, Buckinghamshire, UK) was used to confirm successful epidural spread. All unintended intradiscal contrast dye spread was confirmed in AP and lateral fluoroscopic views, and the affected intervertebral disc level was documented (Fig. 2A, B). To be accepted as a confirmed event, 2 reviewers (J.H.H. and S.Y.K.) examined all images for either vascular or intradiscal injection and both had to agree. With a successful epidural contrast spread without intradiscal or intravascular injection, a mixture of 40 mg of triamcinolone and 3 mL of 0.5% mepivacaine was injected. In cases of inadvertent intradiscal or intravascular injections, needle repositioning was done until successful epidural spread was obtained and the steroid was then injected. When an intravascular injection was unavoidable in
FIGURE 2. Anteroposterior (A) and lateral (B) fluoroscopic image showing intradiscal dye spread. © 2013 American Society of Regional Anesthesia and Pain Medicine
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Hong et al
spite of several attempts of needle repositioning, injecting any medication at that level was abandoned. To ensure the lack of intravascular injection, an aspiration test was performed using a 3-mL syringe. A “positive aspiration” was recorded when blood appeared in the hub spontaneously, without negative pressure, or when blood appeared after the plunger of the syringe was pulled back with negative pressure. Then, 1 mL of contrast dye was injected at each vertebral level and a static fluoroscopic image was taken. After observing the static image pattern, 1 mL of additional contrast was injected under real-time fluoroscopic guidance. The real-time images were classified as (1) epidural (Fig. 3A, B), (2) epidural and vascular (Fig. 3C), or (3) vascular (Fig. 3D). If the contrast showed a characteristic transient pattern and immediately disappeared without epidural spread, the injection was considered intravascular. If the contrast showed a transient pattern as well as epidural spread, the injection was documented as vascular and epidural. In both cases, vascular and vascular/epidural, the needle was repositioned to avoid the intravascular injection of the steroid.
RESULTS This study included 251 TFESIs performed on 219 patients (mean age, 60 years; range, 23–88 years). One hundred twenty patients were diagnosed with spinal stenosis, 95 patients with herniated nucleus pulposus, 2 patients with internal disc disruption, and 2 patients with failed back surgery syndrome.
The overall incidence of intradiscal injection was 2.3% (6/251). Six intradiscal injections occurred in 6 patients. Five intradiscal injections occurred at the L4-5 level and 1 at the L5-S1 level (Fig. 2A, B). The 6 patients who showed intradiscal dye appearance were given intravenous antibiotics (cefazolin, 1 g). None of these patients reported any intradiscal or epidural infection. The most common findings among patients with intradiscal injections were central and lateral canal narrowing combined with disc extrusion or protrusion (Table 1). The overall incidence of intravascular injection was 15.5% (39/251); vascular and epidural injections were 12.7% (32/251), whereas vascular injection alone was 2.8% (7/251). The sample size at each lumbar level was too small to make any statistically significant conclusion regarding the incidence of intravascular injection at each vertebral level (Table 2). One patient had an accidental dural puncture with postdural puncture headache, which spontaneously resolved after 1 week. Other observed complications included postinjection back soreness (8/251), dizziness (4/251), transient leg weakness (2/251), and paresthesia during the procedure (5/251). Among the 39 documented cases of intravascular injections, including simultaneous intravascular and epidural injections, positive blood aspiration was observed in 8 (sensitivity, 20.5%; Table 3), whereas positive intravascular injection confirmed with static fluoroscopic image occurred in 20 cases (sensitivity, 51.2%; Table 4). Among the 212 confirmed nonvascular injection cases based on real-time fluoroscopy and contrast dye, negative blood aspiration was observed in 202 cases (specificity, 95.2%; Table 3), whereas the absence of intravascular dye
FIGURE 3. Anteroposterior and lateral fluoroscopic images of contrast injection during the TFESI. A, Anteroposterior. B, Lateral fluoroscopic image of contrast dye spread along the epidural space. C, Lateral fluoroscopic image of the contrast dye spread in the epidural and intravascular space (black arrow). D, Lateral fluoroscopic image of the intravascular spread of contrast dye (black arrow).
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Intradiscal Incidence During TFESI
TABLE 1. Clinical Characteristics of Patients With Inadvertent Intradiscal Injections During Lumbar TFESIs Patient
Symptoms
Previous Surgery
Age, y
Sex
A
73
M
Left leg pain on walking
None
B
59
F
None
C
64
F
LBP and left leg pain for 3 mo LBP and right buttock pain
D
60
F
Left leg pain on walking
None
E
65
F
None
F
58
M
Left side buttock, thigh, calf painful tingling sensation Right buttock pain on walking
None
None
Magnetic Resonance Imaging
Side/Level
Result
Spondylolisthesis of L4 on L5, and narrowing of central and lateral canal at L4-5 due to spondylolisthesis Disc bulging and central protrusion at L4-5 Central and lateral canal narrowing at L5-S1 due to right subarticular disc extrusion Central and lateral canal narrowing at L4-5 due to disc bulging and hypertrophic change of facet joint Central and lateral canal narrowing at L4-5 due to disc bulging and hypertrophy of facet joint Narrowing of central and lateral canal at L4-5 due to spondylolisthesis and disc bulging
Left/L4-5
Partial pain relief and reduction of symptoms, but recur of symptoms
Left/L4-5
Complete pain relief
injection, using static radiography, was confirmed in all 212 injections (specificity, 100%; Table 4).
DISCUSSION In this study, the overall incidence of intradiscal injection was 2.3%; Candido et al10 and Plastaras et al11 reported incidences of 0.25% and 0.17%, respectively. The large discrepancy between the literature and our study may be attributed to other studies’ underestimation of the complication rate and the limitations of retrospective studies to probe complications uniformly. Candido et al10 also pointed out that intradiscal injections may often go unrecognized by the interventionalist. Further, Candido et al10 acknowledged that the denominator for the calculation of incidence of intradiscal injection might be inflated, because patients receiving multiple injections with multiple approaches to the lumbar spine were included. Our results suggest that inadvertent intradiscal injection during TFESI is not rare; pain physicians performing TFESI should be aware of this potential complication and take steps to prevent and minimize the complication. Carragee et al24 demonstrated that significant disc degenerations and herniations occurred in his patients who received discography compared with control group. The most serious complication after inadvertent disc penetration is discitis due
TABLE 2. Incidence of Vascular Injection of Contrast During Lumbar Transforaminal Epidural Injections
8 8 0 0 0
68 55 9 4 13
158 132 23 3 26
17 17 0 0 0
251 (100) 212 (84.4) 32 (12.7) 7 (2.8) 39 (15.5)
Data are numbers of injections (P = 0.219).
© 2013 American Society of Regional Anesthesia and Pain Medicine
Pain relief and reduction of symptoms for 2 wk
Left/L4-5
Pain relief and reduction of symptoms, but recur of symptoms 3 mo later Complete relief of pain and reduction of symptoms
Left/L4-5 Right/L4-5
Slightly improved leg pain but no improvement of leg weakness
to its refractoriness to treatment and potential for permanent neurological complications.12 No previous studies have examined the incidence of discitis after inadvertent disc entry during TFESI. In our study, none of the 6 inadvertent intradiscal injections resulted in infection. The prophylactic use of antibiotics in discography has been supported.12 Plastaras et al11 suggested that ipsilateral foraminal stenosis is a risk factor for intradiscal injection, which was also found in our study. Five of 6 intradiscal injection patients had a lateral canal narrowing confirmed by magnetic resonance imaging. Cohen et al6 suggested that inadvertent intradiscal injection is most likely attributed to a far lateral disc herniation. Although none of our study patients had this type of herniation, it is possible that the degenerative process of the annular fiber may generate an adjacent pathway to the epidural space, allowing the contrast dye or medication to spread intradiscally. As a probable explanation, Plastaras et al11 suggested that the negative pressure of intradiscal space was related with a severely degenerated vacuum disc with disrupted annulus, which may pull the contrast dye from the epidural space into the disc due to the pressure gradient. In our study, the overall incidence of intravascular uptake is 15.5%, which is similar to the results reported by Smuck
TABLE 3. Sensitivity, Specificity, and Predictive Values of the Aspiration Test Intravascular Uptake During Real-Time Fluoroscopy
L2-L3 L3-L4 L4-L5 L5-S1 Total (%) No. injections Epidural only Epidural + vascular Vascular only Total vascular (%)
Right/L5-S1
Aspiration Test Positive Negative Total
Positive
Negative
Total
8 31 39
10 202 212
18 233 251
Data are numbers of injections. Sensitivity, 20.5%; specificity, 95.2%.
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TABLE 4. Sensitivity, Specificity, and Predictive Values of the Static Image With Contrast Enhancement
Static Image With Contrast Enhancement Positive Negative Total
Intravascular Uptake During Real-Time Fluoroscopy Positive
Negative
Total
20 19 39
0 212 212
20 231 251
Data are numbers of injections. Sensitivity, 51.2%; specificity, 100%.
et al,18 who found a 13.1% incidence of intravascular uptake in transforaminal epidural injections and a 13.3% incidence of caudal epidural block. If the needle tip is only partially placed in a blood vessel, the contrast dye spread may be observed in both the intravascular and epidural space. Among all TFESI cases, simultaneous intravascular and epidural injection accounted for 12.7%, whereas intravascular accounted for only 2.8% of the cases. Smuck et al18 reported that more than half (8.9%) of all accidental intravascular injections (13.1%) during TFESI showed the simultaneous spread of contrast in the blood vessel and epidural space. Our data suggest that an aspiration test should not be used as a credible indicator of confirming extravascular needle placement. This finding is in accordance with those of previous studies.16,21,22 The epidural veins are a relatively thin-walled, low-pressure system and consequently collapse rapidly upon aspiration. In addition, we identified several cases in which blood appeared in the hub of the needle although contrast dye revealed no intravascular uptake. Therefore, the appearance of blood in the needle hub may not anticipate intravascular needle placement. Such cases can possibly happen if the needle has partially damaged the vascular structure during its way to the target location, thereby letting a small amount of blood return through the needle. Conversely, the specificity of the aspiration test was 95.2% in our study, which is similar to that reported for lumbar TFESI (97.9%).21 Intermittent fluoroscopy fails to detect nearly half of the vascular injections compared with live fluoroscopy. This finding also agrees with previous studies.16,18 The number of missed intravascular injections increased when epidural and vascular contrast flow appeared simultaneously. Among 19 missed intravascular injections in the static image, 18 cases were from simultaneous epidural and intravascular injections and only 1 was documented during an intravascular injection. Smuck et al18 reported that failure to detect intravascular injection on static image increased with simultaneous epidural and intravascular injections. The simultaneous uptake of contrast is better visualized in real-time fluoroscopy16–18 or DSA19,20 than the static image. According to the report by McLean et al,20 the addition of DSA technology to the real-time fluoroscopic image procedure nearly doubled the detection of intravascular incidence in cervical transforaminal epidural injection. Better visualization of contrast material at lower volumes than with the conventional fluoroscopy is the advantage of real-time DSA.19,20 Disadvantages of real-time DSA include additional radiation exposure to the patient and medical personnel, and the high cost of new and upgraded fluoroscopic equipment.20 In conclusion, intradiscal injection during TFESI is not uncommon. Special attention should be added to minimize the risk of inadvertent disk penetration. Both the aspiration test and
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static radiography frequently missed the vascular injection of contrast during TFESI. We suggest that contrast dye injection during TFESI be performed under real-time fluoroscopy or DSA to enhance diagnostic and therapeutic responses while minimizing the risk of complications.
REFERENCES 1. Ackerman WE 3rd, Ahmad M. The efficacy of lumbar epidural steroid injections in patients with lumbar disc herniations. Anesth Analg. 2007;104:1217–1222. 2. Lee JH, An JH, Lee SH. Comparison of the effectiveness of interlaminar and bilateral transforaminal epidural steroid injections in treatment of patients with lumbosacral disc herniation and spinal stenosis. Clin J Pain. 2009;25:206–210. 3. Sitzman B. Epidural injections. In: Fenton DS, Czervionke LF, eds. Image-guided Spine Intervention. Philadelphia, PA: WB Saunders; 2003. 4. Lee JW, Kim SH, Choi JY, et al. Transforaminal epidural steroid injection for lumbosacral radiculopathy: preganglionic versus conventional approach. Korean J Radiol. 2006;7:139–144. 5. Murthy NS, Maus TP, Behrns CL. Intraforaminal location of the great anterior radiculomedullary artery (artery of Adamkiewicz): a retrospective review. Pain Med. 2010;11:1756–1764. 6. Cohen SP, Maine DN, Shockey SM, Kudchadkar S, Griffith S. Inadvertent disk injection during transforaminal epidural steroid injection: steps for prevention and management. Pain Med. 2008;9:688–694. 7. Haspeslagh S, Van Zundert J, Puylaert M, Heylen R, van Kleef M, Vissers K. Unilateral diagnostic infiltration of lumbar L3 nerve root resulting in an inadvertent discogram: the importance of fluoroscopic guidance in interventional pain therapy. Anesthesiology. 2004;100:1019–1021. 8. Huang J, Kwa A. Lumbar discogram resulting from lumbar interlaminar epidural injection. J Clin Anesth. 2004;16:296–298. 9. Finn KP, Case JL. Disk entry: a complication of transforaminal epidural injection—a case report. Arch Phys Med Rehabil. 2005;86:1489–1491. 10. Candido KD, Katz JA, Chinthagada M, McCarthy RA, Knezevic NN. Incidence of intradiscal injection during lumbar fluoroscopically guided transforaminal and interlaminar epidural steroid injections. Anesth Analg. 2010;110:1464–1467. 11. Plastaras CT, Casey E, Goodman BS, Chou L, Roth D, Rittenberg J. Inadvertent intradiscal contrast flow during lumbar transforaminal epidural steroid injections: a case series examining the prevalence of intradiscal injection as well as potential associated factors and adverse events. Pain Med. 2010;11:1765–1773. 12. Cohen SP, Larkin TM, Barna SA, Palmer WE, Hecht AC, Stojanovic MP. Lumbar discography: a comprehensive review of outcome studies, diagnostic accuracy, and principles. Reg Anesth Pain Med. 2005;30:163–183. 13. Kennedy DJ, Dreyfuss P, Aprill CN, Bogduk N. Paraplegia following image-guided transforaminal lumbar spine epidural steroid injection: two case reports. Pain Med. 2009;10:1389–1394. 14. Lyders EM, Morris PP. A case of spinal cord infarction following lumbar transforaminal epidural steroid injection: MR imaging and angiographic findings. Am J Neuroradiol. 2009;30:1691–1693. 15. Thefenne L, Dubecq C, Zing E, et al. A rare case of paraplegia complicating a lumbar epidural infiltration. Ann Phys Rehabil Med. 2010;53:575–583. 16. Lee CJ, Kim YC, Shin JH, et al. Intravascular injection in lumbar medial branch block: a prospective evaluation of 1433 injections. Anesth Analg. 2008;106:1274–1278.
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17. Furman MB, Giovanniello MT, O’Brien EM. Incidence of intravascular penetration in transforaminal cervical epidural steroid injections. Spine (Phila Pa 1976). 2003;28:21–25.
21. Furman MB, O’Brien EM, Zgleszewski TM. Incidence of intravascular penetration in transforaminal lumbosacral epidural steroid injections. Spine (Phila Pa 1976). 2000;25:2628–2632.
18. Smuck M, Fuller BJ, Chiodo A, et al. Accuracy of intermittent fluoroscopy to detect intravascular injection during transforaminal epidural injections. Spine (Phila Pa 1976). 2008;33:E205–E210.
22. Sullivan WJ, Willick SE, Chira-Adisai W, et al. Incidence of intravascular uptake in lumbar spinal injection procedures. Spine (Phila Pa 1976). 2000;25:481–486.
19. Lee MH, Yang KS, Kim YH, et al. Accuracy of live fluoroscopy to detect intravascular injection during lumbar transforaminal epidural injections. Korean J Pain. 2010;23:19–23.
23. Smuck M, Fuller BJ, Yoder B, Huerta J. Incidence of simultaneous epidural and vascular injection during lumbosacral transforaminal epidural injections. Spine J. 2007;7:79–82.
20. McLean JP, Sigler JD, Plastara CT, Garvan CW, Rittenberg JD. The rate of detection of intravascular injection in cervical transforaminal epidural steroid injections with and without digital subtraction angiography. PM R. 2009;1:636–642.
24. Carragee EJ, Don AS, Hurwitz EL, Cuellar JM, Carrino JA, Herzog R. 2009 ISSLS Prize Winner: Does discography cause accelerated progression of degeneration changes in the lumbar disc: a ten-year matched cohort study. Spine (Phila Pa 1976). 2009;34:2338–2345.
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Analysis of Inadvertent Intradiscal and Intravascular Injection During Lumbar Transforaminal Epidural Steroid Injections A Prospective Study Ji H. Hong, MD, PhD,* Sae Y. Kim, MD,* Billy Huh, MD, PhD,† and Hyun H. Shin, MD* Background and Objectives: Inadvertent intradiscal injection during a lumbar transforaminal epidural steroid injection (TFESI) can be critical given the possibility of discitis and disc degeneration. Intravascular steroid injection can result in devastating neurologic complications. We sought to identify the incidence of intradiscal and intravascular injection during lumbar TFESI and determine whether an aspiration test and static fluoroscopic image can be used to predict intravascular needle placement. Methods: We evaluated 251 TFESIs in 219 patients. All TFESIs were performed by one of the authors using classic TFESI technique. After final needle position was confirmed using biplanar fluoroscopy, 1 mL of contrast was injected after negative blood or cerebrospinal fluid aspiration. Using static and real-time fluoroscopy, we assessed the incidences of intradiscal injection, blood flashback, and the presence of intravascular contrast spread. Results: The incidence of intradiscal injections was 2.3% (6/251). Six intradiscal injections were observed, all among patients who had not previously undergone disc surgery. Five intradiscal injections occurred at the L4-5 level and 1 at the L5-S1 level. The incidence of overall intravascular injection was 15.5% (39/251), of which the incidence of simultaneous vascular and epidural injection was 12.7% (32/251), whereas intravascular injection only was 2.8% (7/251). The sensitivities for detecting intravascular access via aspiration or static fluoroscopic image with contrast were 20.5% and 51.2%, respectively. Conclusions: Inadvertent intradiscal injection during TFESI is not rare. Physicians who perform interventional pain procedures should increase their awareness of related potential complications. The aspiration test and static image of fluoroscope often fail to detect the intravascular injection during the TFESI. Real-time fluoroscopy should be the gold standard for confirming intravascular injection. (Reg Anesth Pain Med 2013;38: 520–525)
L
umbar epidural steroid injection is one of the most frequently performed interventional pain management procedures for lumbar radiculopathy. The transforaminal, interlaminar, and caudal routes are 3 techniques available to access and deliver medication to the epidural space.1,2 Transforaminal epidural steroid injection (TFESI) can be carried out using either the classic or
From the *Department of Anesthesiology and Pain Medicine, Keimyung University Dong San Hospital, School of Medicine, Daegu, Korea; and †Department of Anesthesiology and Pain Medicine, Duke University Medical Center, Durham, NC. Accepted for publication July 31, 2013. Address correspondence to: Ji H. Hong, MD, PhD, Department of Anesthesiology and Pain Medicine, Keimyung University Dong San Hospital, 56 Dal-Sung Ro, Jung gu, Daegu 700-712, Korea (e‐mail: [email protected]). The authors declare no conflict of interest. This study was supported by BISA research funds from Keimyung University in 2010. This study was approved by the institutional review board of Keimyung University Dong San Hospital (IRB No 12-88). Copyright © 2013 by American Society of Regional Anesthesia and Pain Medicine ISSN: 1098-7339 DOI: 10.1097/AAP.0000000000000010
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retrodiscal approach. The classic technique targets the inferior aspect of the midsagittal bisector in the anteroposterior (AP) fluoroscopic view (6-o’clock position) of the pedicle, with the final needle position in the superior dorsal or ventral aspect of the intervertebral foramen on the lateral fluoroscopic view.3 The needle tip target for the retrodiscal technique is the inferior ventral region of intervertebral foramen on the lateral fluoroscopic view, just posterior to the annulus of the disc and posterior longitudinal ligament.4,5 According to the report by Murthy et al,5 the artery of Adamkiewicz was overwhelmingly located in the superior aspect of the neural foramen; therefore, they suggested that epidural needle placement at L3 and above needs to be directed to an inferior and slightly posterior position within the foramen. Due to the purported advantage of the delivery of high concentration of medication to the ventral epidural space,1,2 pain physicians commonly perform transforaminal injections of steroids, yet the procedure is not without risk.6 Recently, there have been several case reports6–9 and 2 retrospective studies10,11 regarding the incidence of intradiscal injection during TFESI. These reports10,11 suggest an incidence of intradiscal injection as low as 0.25% and 0.17%. In our clinical practices, however, we encounter inadvertent intradiscal injection not infrequently; therefore, we questioned the reported low incidence. The risk of discitis, with potentially significant morbidity, mandates a technique that limits this complication.12 We hypothesized that with a prospective study design we would encounter intradiscal injection during TFESI more commonly than previously reported. Several reports have documented serious complications associated with the lumbosacral epidural injection, including paraplegia and spinal cord infarction with irreversible neurologic outcomes.13–15 Many of these adverse outcomes are thought to be secondary to intravascular injection/embolization of corticosteroid particulates via the radicular arteries. It has been suggested that the confirmation of intravascular injection during TFESI should be assessed under the guidance of real-time fluoroscopy,16–18 and the use of digital subtraction angiography (DSA).19,20 The incidence of intravascular injection has been reported to be 8.5% to 13.1% of fluoroscopically guided lumbar TFESI depending on the level of injection.21–23 The commonly used method of contrast injection after an aspiration test has a low sensitivity for identifying intravascular injection (34.1%–45.9%),16,17,21 and epidural injections performed under static image guidance often fail to detect intravascular injection (57%–59.1%).16,18 The aim of the current study was to identify the incidence of both intradiscal and intravascular injection in TFESI, using static and real-time image guidance.
METHODS This study was approved by the ethics committee of our institution, and written informed consent was obtained from all patients after explaining the risks, benefits, and goals of the study.
Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
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Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
Intradiscal Incidence During TFESI
FIGURE 1. Anteroposterior (A) and lateral (B) fluoroscopic image of the final needle position for TFESIs.
Data were collected on the patients’ age, sex, type of disease, intradiscal dye appearance, presence of vascular spread of contrast on static, real-time fluoroscopic images, blood flashback, and spinal level where TFESI were performed. We hypothesized that the probability of intradiscal and vascular injections of contrast was 2% and 15%, respectively, based on the review of related articles6–11,16,17,21–23 and the results of our preliminary study. On the basis of an α error level of 0.05, a β error level of 0.2, and a 2-sided test, 234 injections were required as a total sample size with an 80% power. All statistical analyses were performed using SPSS version 17 (IBM, Chicago, Illinois). A χ2 test was used to compare categorical variables. From September 2010 to July 2011, 219 consecutive patients were enrolled and received 251 fluoroscopically guided TFESI using the classic technique. Thirty-two patients received 2-level TFESI, and the remaining 187 patients received 1-level TFESI. Inclusion criteria were patients with radicular pain from spinal stenosis, herniated nucleus pulposus, internal disc disruption, or failed back surgery syndrome. Exclusion criteria were patients who had known allergies to contrast or local anesthetics or who had experienced coagulopathy. Patients who received either interlaminar or caudal epidural injections were excluded. All TFESI were performed by an interventional pain specialist (J.H.H.) with more than 7-year experience in image-guided injections. Using the classic approach for TFESI as described previously, the injection target was the midsagittal bisector (“6-o’clock
position”) of the pedicle in the AP projection. After marking the skin entry point under image guidance, the skin was prepared and draped in a sterile fashion. The C-arm was rotated obliquely to ensure injection at the neural foramen. The skin entry site was infiltrated with 1% lidocaine, and 23-gauge Quincke type spinal needle was advanced along the axis of the x-ray beam toward the 6-o’clock position of the pedicle, avoiding the segmental nerve and intervertebral disc. Lateral radiographic imaging was also used while advancing toward the intervertebral foramen and superolateral to the exiting spinal nerve with a special attention to minimize the risk of disc puncture. The final needle position was confirmed with AP and lateral fluoroscopic views, and the needle tip location was confirmed at the superior ventral aspect of the neural foramen on the lateral view (Fig. 1A, B). Up to 3 mL of contrast dye (Omnipaque 300; GE Healthcare, Little Chalfont, Buckinghamshire, UK) was used to confirm successful epidural spread. All unintended intradiscal contrast dye spread was confirmed in AP and lateral fluoroscopic views, and the affected intervertebral disc level was documented (Fig. 2A, B). To be accepted as a confirmed event, 2 reviewers (J.H.H. and S.Y.K.) examined all images for either vascular or intradiscal injection and both had to agree. With a successful epidural contrast spread without intradiscal or intravascular injection, a mixture of 40 mg of triamcinolone and 3 mL of 0.5% mepivacaine was injected. In cases of inadvertent intradiscal or intravascular injections, needle repositioning was done until successful epidural spread was obtained and the steroid was then injected. When an intravascular injection was unavoidable in
FIGURE 2. Anteroposterior (A) and lateral (B) fluoroscopic image showing intradiscal dye spread. © 2013 American Society of Regional Anesthesia and Pain Medicine
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Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
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spite of several attempts of needle repositioning, injecting any medication at that level was abandoned. To ensure the lack of intravascular injection, an aspiration test was performed using a 3-mL syringe. A “positive aspiration” was recorded when blood appeared in the hub spontaneously, without negative pressure, or when blood appeared after the plunger of the syringe was pulled back with negative pressure. Then, 1 mL of contrast dye was injected at each vertebral level and a static fluoroscopic image was taken. After observing the static image pattern, 1 mL of additional contrast was injected under real-time fluoroscopic guidance. The real-time images were classified as (1) epidural (Fig. 3A, B), (2) epidural and vascular (Fig. 3C), or (3) vascular (Fig. 3D). If the contrast showed a characteristic transient pattern and immediately disappeared without epidural spread, the injection was considered intravascular. If the contrast showed a transient pattern as well as epidural spread, the injection was documented as vascular and epidural. In both cases, vascular and vascular/epidural, the needle was repositioned to avoid the intravascular injection of the steroid.
RESULTS This study included 251 TFESIs performed on 219 patients (mean age, 60 years; range, 23–88 years). One hundred twenty patients were diagnosed with spinal stenosis, 95 patients with herniated nucleus pulposus, 2 patients with internal disc disruption, and 2 patients with failed back surgery syndrome.
The overall incidence of intradiscal injection was 2.3% (6/251). Six intradiscal injections occurred in 6 patients. Five intradiscal injections occurred at the L4-5 level and 1 at the L5-S1 level (Fig. 2A, B). The 6 patients who showed intradiscal dye appearance were given intravenous antibiotics (cefazolin, 1 g). None of these patients reported any intradiscal or epidural infection. The most common findings among patients with intradiscal injections were central and lateral canal narrowing combined with disc extrusion or protrusion (Table 1). The overall incidence of intravascular injection was 15.5% (39/251); vascular and epidural injections were 12.7% (32/251), whereas vascular injection alone was 2.8% (7/251). The sample size at each lumbar level was too small to make any statistically significant conclusion regarding the incidence of intravascular injection at each vertebral level (Table 2). One patient had an accidental dural puncture with postdural puncture headache, which spontaneously resolved after 1 week. Other observed complications included postinjection back soreness (8/251), dizziness (4/251), transient leg weakness (2/251), and paresthesia during the procedure (5/251). Among the 39 documented cases of intravascular injections, including simultaneous intravascular and epidural injections, positive blood aspiration was observed in 8 (sensitivity, 20.5%; Table 3), whereas positive intravascular injection confirmed with static fluoroscopic image occurred in 20 cases (sensitivity, 51.2%; Table 4). Among the 212 confirmed nonvascular injection cases based on real-time fluoroscopy and contrast dye, negative blood aspiration was observed in 202 cases (specificity, 95.2%; Table 3), whereas the absence of intravascular dye
FIGURE 3. Anteroposterior and lateral fluoroscopic images of contrast injection during the TFESI. A, Anteroposterior. B, Lateral fluoroscopic image of contrast dye spread along the epidural space. C, Lateral fluoroscopic image of the contrast dye spread in the epidural and intravascular space (black arrow). D, Lateral fluoroscopic image of the intravascular spread of contrast dye (black arrow).
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Regional Anesthesia and Pain Medicine • Volume 38, Number 6, November-December 2013
Intradiscal Incidence During TFESI
TABLE 1. Clinical Characteristics of Patients With Inadvertent Intradiscal Injections During Lumbar TFESIs Patient
Symptoms
Previous Surgery
Age, y
Sex
A
73
M
Left leg pain on walking
None
B
59
F
None
C
64
F
LBP and left leg pain for 3 mo LBP and right buttock pain
D
60
F
Left leg pain on walking
None
E
65
F
None
F
58
M
Left side buttock, thigh, calf painful tingling sensation Right buttock pain on walking
None
None
Magnetic Resonance Imaging
Side/Level
Result
Spondylolisthesis of L4 on L5, and narrowing of central and lateral canal at L4-5 due to spondylolisthesis Disc bulging and central protrusion at L4-5 Central and lateral canal narrowing at L5-S1 due to right subarticular disc extrusion Central and lateral canal narrowing at L4-5 due to disc bulging and hypertrophic change of facet joint Central and lateral canal narrowing at L4-5 due to disc bulging and hypertrophy of facet joint Narrowing of central and lateral canal at L4-5 due to spondylolisthesis and disc bulging
Left/L4-5
Partial pain relief and reduction of symptoms, but recur of symptoms
Left/L4-5
Complete pain relief
injection, using static radiography, was confirmed in all 212 injections (specificity, 100%; Table 4).
DISCUSSION In this study, the overall incidence of intradiscal injection was 2.3%; Candido et al10 and Plastaras et al11 reported incidences of 0.25% and 0.17%, respectively. The large discrepancy between the literature and our study may be attributed to other studies’ underestimation of the complication rate and the limitations of retrospective studies to probe complications uniformly. Candido et al10 also pointed out that intradiscal injections may often go unrecognized by the interventionalist. Further, Candido et al10 acknowledged that the denominator for the calculation of incidence of intradiscal injection might be inflated, because patients receiving multiple injections with multiple approaches to the lumbar spine were included. Our results suggest that inadvertent intradiscal injection during TFESI is not rare; pain physicians performing TFESI should be aware of this potential complication and take steps to prevent and minimize the complication. Carragee et al24 demonstrated that significant disc degenerations and herniations occurred in his patients who received discography compared with control group. The most serious complication after inadvertent disc penetration is discitis due
TABLE 2. Incidence of Vascular Injection of Contrast During Lumbar Transforaminal Epidural Injections
8 8 0 0 0
68 55 9 4 13
158 132 23 3 26
17 17 0 0 0
251 (100) 212 (84.4) 32 (12.7) 7 (2.8) 39 (15.5)
Data are numbers of injections (P = 0.219).
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Pain relief and reduction of symptoms for 2 wk
Left/L4-5
Pain relief and reduction of symptoms, but recur of symptoms 3 mo later Complete relief of pain and reduction of symptoms
Left/L4-5 Right/L4-5
Slightly improved leg pain but no improvement of leg weakness
to its refractoriness to treatment and potential for permanent neurological complications.12 No previous studies have examined the incidence of discitis after inadvertent disc entry during TFESI. In our study, none of the 6 inadvertent intradiscal injections resulted in infection. The prophylactic use of antibiotics in discography has been supported.12 Plastaras et al11 suggested that ipsilateral foraminal stenosis is a risk factor for intradiscal injection, which was also found in our study. Five of 6 intradiscal injection patients had a lateral canal narrowing confirmed by magnetic resonance imaging. Cohen et al6 suggested that inadvertent intradiscal injection is most likely attributed to a far lateral disc herniation. Although none of our study patients had this type of herniation, it is possible that the degenerative process of the annular fiber may generate an adjacent pathway to the epidural space, allowing the contrast dye or medication to spread intradiscally. As a probable explanation, Plastaras et al11 suggested that the negative pressure of intradiscal space was related with a severely degenerated vacuum disc with disrupted annulus, which may pull the contrast dye from the epidural space into the disc due to the pressure gradient. In our study, the overall incidence of intravascular uptake is 15.5%, which is similar to the results reported by Smuck
TABLE 3. Sensitivity, Specificity, and Predictive Values of the Aspiration Test Intravascular Uptake During Real-Time Fluoroscopy
L2-L3 L3-L4 L4-L5 L5-S1 Total (%) No. injections Epidural only Epidural + vascular Vascular only Total vascular (%)
Right/L5-S1
Aspiration Test Positive Negative Total
Positive
Negative
Total
8 31 39
10 202 212
18 233 251
Data are numbers of injections. Sensitivity, 20.5%; specificity, 95.2%.
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Hong et al
TABLE 4. Sensitivity, Specificity, and Predictive Values of the Static Image With Contrast Enhancement
Static Image With Contrast Enhancement Positive Negative Total
Intravascular Uptake During Real-Time Fluoroscopy Positive
Negative
Total
20 19 39
0 212 212
20 231 251
Data are numbers of injections. Sensitivity, 51.2%; specificity, 100%.
et al,18 who found a 13.1% incidence of intravascular uptake in transforaminal epidural injections and a 13.3% incidence of caudal epidural block. If the needle tip is only partially placed in a blood vessel, the contrast dye spread may be observed in both the intravascular and epidural space. Among all TFESI cases, simultaneous intravascular and epidural injection accounted for 12.7%, whereas intravascular accounted for only 2.8% of the cases. Smuck et al18 reported that more than half (8.9%) of all accidental intravascular injections (13.1%) during TFESI showed the simultaneous spread of contrast in the blood vessel and epidural space. Our data suggest that an aspiration test should not be used as a credible indicator of confirming extravascular needle placement. This finding is in accordance with those of previous studies.16,21,22 The epidural veins are a relatively thin-walled, low-pressure system and consequently collapse rapidly upon aspiration. In addition, we identified several cases in which blood appeared in the hub of the needle although contrast dye revealed no intravascular uptake. Therefore, the appearance of blood in the needle hub may not anticipate intravascular needle placement. Such cases can possibly happen if the needle has partially damaged the vascular structure during its way to the target location, thereby letting a small amount of blood return through the needle. Conversely, the specificity of the aspiration test was 95.2% in our study, which is similar to that reported for lumbar TFESI (97.9%).21 Intermittent fluoroscopy fails to detect nearly half of the vascular injections compared with live fluoroscopy. This finding also agrees with previous studies.16,18 The number of missed intravascular injections increased when epidural and vascular contrast flow appeared simultaneously. Among 19 missed intravascular injections in the static image, 18 cases were from simultaneous epidural and intravascular injections and only 1 was documented during an intravascular injection. Smuck et al18 reported that failure to detect intravascular injection on static image increased with simultaneous epidural and intravascular injections. The simultaneous uptake of contrast is better visualized in real-time fluoroscopy16–18 or DSA19,20 than the static image. According to the report by McLean et al,20 the addition of DSA technology to the real-time fluoroscopic image procedure nearly doubled the detection of intravascular incidence in cervical transforaminal epidural injection. Better visualization of contrast material at lower volumes than with the conventional fluoroscopy is the advantage of real-time DSA.19,20 Disadvantages of real-time DSA include additional radiation exposure to the patient and medical personnel, and the high cost of new and upgraded fluoroscopic equipment.20 In conclusion, intradiscal injection during TFESI is not uncommon. Special attention should be added to minimize the risk of inadvertent disk penetration. Both the aspiration test and
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static radiography frequently missed the vascular injection of contrast during TFESI. We suggest that contrast dye injection during TFESI be performed under real-time fluoroscopy or DSA to enhance diagnostic and therapeutic responses while minimizing the risk of complications.
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