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Pain Medicine: Brief Reports

Incidence of Intradiscal Injection During Lumbar Fluoroscopically Guided Transforaminal and Interlaminar Epidural Steroid Injections

Candido, Kenneth D. MD*; Katz, Jeffrey A. MD; Chinthagada, Mariadas MD; McCarthy, Robert A. Pharm D; Knezevic, Nebojsa Nick MD, PhD*

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doi: 10.1213/ANE.0b013e3181d6bd12


Lumbar injection of corticosteroids is one of the most frequently performed interventional pain management procedures in the United States, although evidence for long-term efficacy is limited.15 Complications from both interlaminar approaches, lumbar epidural steroid injections (LESIs), and transforaminal approaches, transforaminal epidural steroid injections (TFESIs), are increasingly being reported, although intradiscal injection using both the respective techniques has been rarely identified.69 Indeed, in our review of 5 contemporary standard reference books dedicated to image-guided epidural injections,1014 we could identify only 1 book that addressed the issue of disk entry using the respective approaches.14 Thus far, there are 5 cases of unintentional intradiscal injections reported without any data describing the frequency with which these injections occur.69 In that regard, this retrospective observational report is the first attempt to quantify the overall rate of intradiscal injection occurring during lumbar steroid injections in 2 large independent fellowship training institutions that use both LESI and TFESI as routine pain-relieving modalities using fluoroscopic guidance for both.


After obtaining IRB approval from both Loyola University Medical Center and Northwestern University/Feinberg School of Medicine, the billing records by Current Procedural Terminology code and pain clinic procedure log books were examined from 2 large fellowship training programs. The total number of LESIs and TFESIs was recorded from July 1, 2004, to June 30, 2007, representing 3 years of accrued data. Data collection was limited to lumbar techniques in which fluoroscopic guidance was used. A total of 4723 LESIs and 2412 TFESIs were performed in the interval. At Loyola University Medical Center, log books detailing every intervention performed, supervising physician, and type of side effect and/or complication were reviewed. At Northwestern University/Feinberg School of Medicine, each practicing pain physician was queried as to the occurrence of intradiscal contrast spread during LESI/TFESI over the interval specified. Written informed consents were obtained from all patients. All procedures were performed by fellows in training under attending supervision, each of whom is fellowship trained and certified by the American Board of Anesthesiology with Added Qualifications in Pain Medicine. Each TFESI was performed using the protocol derived from a standard reference book.10

For TFESI, an anteroposterior (AP) fluoroscopic view was obtained, identifying the target level. Next, the C-arm was rotated obliquely in the coronal plane until the facet joint was delineated. The camera was next obliqued approximately 15° in the caudocephalad direction to clearly identify the superior pars interarticularis. After performing a skin infiltration, the block needle (22-gauge, blunt and curved tipped) was inserted and was advanced toward the tip of the superior pars. After contacting the pars, the needle was “walked off” in a cephalad direction. If contact with the pars was not made, rotation of the needle hub was performed, producing translational rotation of the needletip to direct it toward the target. Lateral fluoroscopy was used to determine the relationship of the advancing needle tip to the neural foramen. Ideal placement occurred with the needle tip in the cephalodorsal quadrant of the intervertebral foramen. On AP view, ideal placement was considered once the needle tip approached the space just below the pedicle, touching an imaginary line drawn vertically through the center of each pedicle. One milliliter water-soluble, iodinated contrast media (Iohexol-Omnipaque®180; Nycomed, Princeton, NJ) was then injected using continual fluoroscopy.

For interlaminar LESI, the same preparations and patient positioning as described above were used. Using AP fluoroscopy, the interlaminar space was identified. Next, after raising a skin wheal, a 20-gauge, 3.5-in. Tuohy-type epidural needle was advanced using the loss of resistance to air technique. AP and lateral imaging were used during advancement. Once the loss of resistance test confirmed that the needle was within the confines of the epidural space, the same volume and type of contrast media as described above was incrementally injected in divided doses. All fluoroscopic images were saved and recorded in the cases in which intradiscal injection was observed.


We identified 7 intradiscal injections; 6 were associated with TFESI and 1 was associated with LESI. Four of 6 patients were men. Patient ages ranged from 38 to 86 years (mean 61.0 ± 16.8 years). Three of 6 patients had undergone previous lumbar spinal surgery. Four of 7 injections were done at the L4-5 level, 2 at the L2-3 level, and 1 at the L5-S1 level. Patients received prophylactic antibiotics after 5 of 7 intradiscal injections (Table 1, Fig. 1). None of the patients in this retrospective review sustained a disk space or epidural infection. The rate of TFESI-associated intradiscal injections was 1:402. The rate of LESI-associated intradiscal injections was 1:4723. We found that the relative rate of this complication is approximately 12 times higher after TFESI versus LESI, which quantifies what Renfrew stated in his reference textbook.14

Table 1:
Clinical Characteristics of Patients with Inadvertent Intradiscal Injections During Epidural Lumbar Steroid Injections
Figure 1:
Patient A. a, Sagittal magnetic resonance imaging (MRI) of the lumbar spine showing anterolisthesis of L5-S1 with disk bulges at L2-3, L4-5, and L3-4 where a subligamentous disk herniation was present, and facet hypertrophic changes at L2-3, L4-5, and L5-S1. b, Axial MRI of L4-5 level showing trefoil deformity caused by central posterior disk bulge, ligamentum flavum hypertrophy, and facet joint hypertrophy. c, Transforaminal epidural steroid injections (TFESIs) at the L4-5 level, right-sided. Extension of intradiscal contrast in an anteroposterior fluoroscopic image. d, TFESI at the L4-5 level, right-sided. Extension of contrast, lateral fluoroscopic image; needle remains in the dorsal portion of the intervertebral space.


Our data demonstrate that intradiscal injection is a rare complication during LESI, but occurs more frequently with TFESI than with LESI. This is the first attempt at quantification of intradiscal injections during lumbar spinal interventions. We relied on both the observed occurrence of intradiscal contrast spread using AP and lateral fluoroscopy and the total number of LESIs and TFESIs performed in 2 university pain fellowship training programs. However, we may have underestimated the rate of this complication because of some potential limitations to this report. The first limitation relates to the fact that intradiscal injection might go unnoticed or unrecognized by the interventionalists. In addition, we included only fluoroscopic techniques of lumbar injections, and it is probable that some nonfluoroscopic LESIs were done in the time interval studied, which could slightly alter the rate. We also did not attempt to identify a rate of intradiscal injection based on the number of individual patients who were treated with lumbar techniques of steroid administration. By including only the actual number of treated patients as the denominator, many of whom received multiple injections using multiple approaches to the lumbar spine, the denominator for both TFESI and LESI would have been smaller than that which we used. However, it is unlikely that the actual ratio of intradiscal injections, heavily represented by the TFESI technique, would have been altered substantially, because no individual received >3 procedures in any 1-year period.


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