What Is A Transforaminal Epidural Steroid Injection?Thoracolumbar transforaminal epidural steroid injections TFESIs are an effective short-term nonsurgical treatment option for managing chronic lumbar radicular spinal pain 1. The procedure is common, with over 1, injections performed on Medicare patients alone in 2. It is most commonly thought to be caused by accidental needle tip penetration of the artery of Transforaminal epidural steroid injection images within the targeted neural foramen and subsequent embolization of particulate steroid into the anterior spinal artery 4 - 6. There has been great interest in developing procedural techniques to reduce the risk of intra-arterial injection of steroid 7 - For cervical CT-fluoroscopic TFESIs, previous literature transforaminal epidural steroid injection images shown haldol meccanismo dazione the extraforaminal needle tip position epidutal to lower incidence of intravascular injection
Thoracolumbar transforaminal epidural steroid injections TFESIs are an effective short-term nonsurgical treatment option for managing chronic lumbar radicular spinal pain 1. The procedure is common, with over 1,, injections performed on Medicare patients alone in 2. It is most commonly thought to be caused by accidental needle tip penetration of the artery of Adamkiewicz within the targeted neural foramen and subsequent embolization of particulate steroid into the anterior spinal artery 4 - 6.
There has been great interest in developing procedural techniques to reduce the risk of intra-arterial injection of steroid 7 - For cervical CT-fluoroscopic TFESIs, previous literature has shown that the extraforaminal needle tip position correlates to lower incidence of intravascular injection The purpose of this study is to determine the safest needle tip position for CT-guided lumbar TFESIs as determined by incidence of intravascular injection.
We also characterize intravascular injections by: Local institutional review board approval was obtained for this retrospective review of clinical and imaging data. We retrospectively searched our radiology information system for all consecutive CT-fluoroscopic guided lumbar TFESIs performed by members of our neuroradiology section at our main academic campus, during a month period February 10, to June 30, Our goal of characterizing needle tip position relative to neural foraminal landmarks required relatively constant morphology among targeted neural foramina.
The injections were performed as previously described 12 with the following additional details: After acquisition of a short-length CT scan for planning purposes, intermittent intraprocedural CT-fluoroscopic imaging was acquired using SmartView GE Healthcare, Milwaukee, Wisconsin triggered by a foot pedal.
Each acquisition created 3 consecutive axial images with the following parameters: All planning and CT-fluoroscopic imaging from the procedure was automatically archived to our hospital PACS, so that we were able to evaluate all imaging acquired at the time of the procedure during our retrospective review. Using intermittent CT-fluoroscopic guidance, needles were positioned at or near the posterior aspect of the neural foramen.
With short-length flexible microbore attached to the needle hub, a trial dose was injected using 0. CT-fluoroscopic imaging was acquired immediately after trial dose injection and scrutinized for intravascular contrast. If intravascular contrast was identified, the needle was then withdrawn a few millimeters, a repeat trial dose injection of 0.
These steps were repeated until no additional intravascular contrast was identified. A cocktail of 80 mg methylprednisolone steroid and 2. Following the procedure, the patient was monitored for 15 minutes to evaluate for minor complications such as vasovagal response or increasing pain or major complications such as cardiovascular or neurologic compromise. Complications were appropriately treated and later reported in the formal procedural report by the attending physician.
All imaging was evaluated by two of the proceduralists GML and VA and a post-graduate-year 4 radiology resident RKU , all of whom were blinded to operator and patient identity.
The 3 reviewers evaluated and characterized all imaging separately. In the case of disagreement, the relevant imaging was re-evaluated in a group setting and a consensus achieved regarding findings and characterization. Our classification of needle tip position is shown in Figure 1. All injections were categorized by needle tip position relative to the targeted lumbar neural foramen at the time of injection using a three-part categorization similar to a scheme previously described for cervical TFESIs 11 , 13 , An intravascular injection were considered to be present if 1 of 2 contrast appearances was identified on CT-fluoroscopy, similar to previously-described criteria 11 , Intravascular injections were classified by likely vessel type into one of three categories Figure Intravascular injections were classified by volume into one of three categories Figure Intravascular injections were classified by procedural phase into one of three categories Figures 4 - Pearson chi-square testing was used to assess differences in vascular injections based on needle position.
Differences in vascular injections were assessed on the basis of age, sex, and prior surgical history by using logistic regression and Pearson chi-square testing as appropriate. If appropriate, post hoc multiple comparison testing was performed. A total of patients underwent lumbar TFESIs in the setting of procedural encounters, most of which were single-level injections. The mean patient average age was 57 years range, 14—88 years.
Characterization of the 52 intravascular injections is given in Table 1. The 2 likely arterial injections occurred with a foraminal needle tip position. Most large-volume injections occurred with the contrast trial dose only. All trace-volume injections were indeterminate in regards to vessel type injected.
The patient was monitored in a hospital outpatient recovery unit and was sent home after the symptoms had resolved. There were no complications attributable to accidental intravascular injection. We have shown that extraforaminal needle tip position correlates to a lower incidence of intravascular injection.
An extraforaminal needle tip may therefore reduce risk for spinal cord infarction and represent a relatively safe needle tip position for lumbar TFESIs.
To our knowledge, we are the first to observe, in the lumbar spine, the direct CT-fluoroscopic imaging evidence of intravascular injection of steroid. Accidental injection of particulate steroid into the artery of Adamkiewicz, with embolization to the anterior spinal artery, is the most commonly-cited cause of spinal cord injury following lumbar TFESI 4 - 6 , 16 , although direct needle injury of the artery of Adamkiewicz has also been suggested as a cause 4 , The specific neural foraminal level and laterality of the artery of Adamkiewicz is highly variable: In practice, the proceduralist must assume that the artery of Adamkiewicz could be present in any thoracic, lumbar, or upper sacral neural foramen.
There are 19 case reports of spinal cord injury following conventional fluoroscopic- or CT-guided thoracolumbar TFESI 3 , 4 , 6 , 8 , 16 , 23 - 29 [ although the complication is known to be underreported due to its medicolegal implications 8 ]. Review of the imaging and procedural descriptions for these 19 case reports shows a foraminal needle location, sometimes deep within the neural foramen, in 7 of these cases; in the remaining 12, insufficient information is provided to determine needle depth relative to the targeted neural foramen 3 , The preponderance of foraminal needle tip positions in these cases suggests a correlation between foraminal needle tip position and spinal cord injury, although alternatively this could represent the fact that foraminal needle tip position may be the most frequently-used technique for lumbar TFESI.
Great concern has been expressed in the literature regarding spinal cord injury as a devastating and unacceptable complication from lumbar TFESI 30 , with the proposal of many procedural techniques that might protect from spinal cord injury. The use of Whitacre needles 10 and non-particulate steroids 37 has also been promoted.
Over one-third of our intravascular injections were likely venous. At a minimum, a large-volume intravenous injection of steroid would be expected to diminish or completely remove the intended concentrated local anti-inflammatory effect of the steroid, and instead convert the injection into an unintended low-dose intravenous steroid injection. In addition, some authors have speculated that accidental intravenous injection of corticosteroid is the cause of Tachon syndrome: Incidence is estimated at 1 in 8, local steroid injections 38 - Given the possible risks of intravenous injection, we suggest the proceduralist make efforts to avoid venous as well as arterial steroid injections.
The limits of this study include those inherent in a retrospective, single-institution review. In addition, we do not have follow-up pain relief data for these injections, so the possibility that extraforaminal needle tip position decreases diagnostic and therapeutic efficacy of the procedure keeps us from suggesting that the extraforaminal zone is the preferred needle tip position for lumbar TFESIs.
A follow-up study correlating needle tip position and pain relief would be useful to address these questions. In conclusion, extraforaminal needle tip position correlates to lower incidence of intravascular injection and may represent a safer needle tip position for lumbar TFESIs. I Conception and design: None; III Provision of study materials or patients: None; IV Collection and assembly of data: A Ghodadra; VI Manuscript writing: All authors; VII Final approval of manuscript: Figure 1 Needle tip position characterized by depth relative to the targeted neural foramen.
Examples of extraforaminal B , junctional C , and foraminal D needle tip positions. Figure 2 Intravascular injections characterized by volume. In this case, a separate, trace-volume intravascular injection is also present small arrowhead ; C large-volume intravascular injection is defined by a perceptible decrease in volume of the dominant epidural contrast collection. In this example, there is no epidural contrast because all contrast has been injected into a vein arrowhead. Figure 3 Intravascular injections characterized by likely vessel type injected.
A,B A likely arterial injection appears as a tiny enhancing vessel in the anterior superior neural foramen A, arrowhead and slightly more superiorly in the adjacent anterolateral spinal canal B, arrowhead , the expected course of the radiculomedullary artery; C a likely venous injections appears as a curvilinear enhancing vessel arrowhead extending anteriorly from the needle tip toward a larger draining venous structure, in this case an iliac vein; D an injection indeterminate for vessel appears as a tiny volume of contrast arrowhead in a small paraspinal vessel which could represent either a small artery or vein.
Figure 4 Intravascular injection during trial dose contrast only. A Initial contrast trial dose injection shows two discrete separate paraspinal foci of intravascular contrast arrowheads ; B the needle is withdrawn several millimeters; C repeat contrast trial dose injection shows expected contrast accumulation and no additional intravascular contrast.
Table 1 Characterization of the 52 intravascular injections Full table. Cite this article as: Extraforaminal needle tip position reduces risk of intravascular injection in CT-fluoroscopic lumbar transforaminal epidural steroid injections. J Spine Surg ;2 4: