Incidence of intravascular penetration in transforaminal lumbosacral epidural steroid injections

Prospective evaluation of the safety of ultrasound-guided cervical medial branch blocks using the in-plane technique

BACKGROUND

While fluoroscopic guidance is currently the imaging standard for cervical medial branch blocks (CMBBs), ultrasound guidance (USG) offers several potential safety advantages such as real-time needle visualization and the ability to detect and avoid critical soft tissue vascular or neural structures. However, no large-scale trials have examined the safety of USG for CMBB.

METHODS

Five hundred patients undergoing 2308 individual block levels were recruited using a prospective cohort design, and blocks were performed in an outpatient office setting using an in-plane USG technique. Primary outcomes included immediate block-related complication, as well as delayed occurrences, in the following 2 weeks. Vascular structures adjacent to the target area, as well as the occurrence of vascular breach, were recorded.

RESULTS

Three minor immediate complications were noted (two subcutaneous hematomas, one vasovagal reaction) comprising 0.13% of blocks (0.03% to 0.38%; 95% two-sided CI), and no delayed events were recorded (0% to 0.16%; 97.5% one-sided CI). Blood vessels were detected and avoided in 8.2% of blocks, and vascular breach was noted in 0.52% of blocks (0.27% to 0.91%; 95% two-sided CI).

CONCLUSION

When performed using an in-plane technique by experienced operators, USG CMBB was found to be safe, with rare minor immediate complications and no further adverse event reported in the following 2 weeks.

TRIAL REGISTRATION NUMBER

NCT04852393.

A review of epidural and non-epidural contrast flow patterns during fluoroscopic and CT-guided epidural steroid injections

Epidural steroid injections are commonly performed using fluoroscopic or CT guidance. With both modalities, the injection of contrast material is necessary before steroid administration to ensure adequate epidural flow and exclude non-epidural flow. While fluoroscopic guidance is conventional, CT is utilized at some centers and can be particularly helpful in the setting of challenging or postoperative anatomy. It is important for proceduralists to be adept at evaluating contrast media flow patterns under both modalities. The goal of this review article is to describe and provide examples of epidural and non-epidural flow patterns on both conventional fluoroscopy and CT. Specific non-epidural patterns discussed include intrathecal flow, intradural/subdural flow, vascular uptake, flow into the retrodural space of Okada, inadvertent facet joint flow, and intradiscal flow.

The Kumar Technique: A Novel and Effective Approach to Transforaminal Epidural Steroid Injections

Background Transforaminal epidural steroid injections (TFESIs) are widely used as a minimally invasive treatment for lumbar radicular pain. This study presents an alternative approach for lumbar TFESI, the Kumar Technique, which utilizes a more lateral and inferior needle starting point to better align the trajectory of the needle with the neural foramen. We hypothesize the Kumar Technique will result in safer and more effective outcomes than the traditional approach to TFESI. This article was previously presented as a poster at the 2023 University of Florida College of Medicine Celebration of Research on February 27-28, 2023, and as an abstract and poster at the 2023 University of Florida Department of Anesthesiology Celebration of Research on March 29, 2023. Methods The charts for 1,424 patients who received lumbar TFESIs were retrospectively reviewed, and patients were stratified into groups receiving either the traditional approach or the Kumar Technique. Outcomes measures included numerical pain scores, measures of functional status and activity limitations, duration of pain relief, and procedural complications. Results Compared to the group undergoing the traditional approach, patients receiving the Kumar Technique reported a significantly greater decrease in average pain (-2.3 (95% CI: -3.0 to -1.6) vs -1.1 (95% CI: -1.4 to -0.7)) and maximum pain (-2.4 (95% CI: -3.2 to -1.6) vs -1.3 (95% CI: -1.8 to -0.9)). Patients receiving the Kumar Technique had a significantly greater likelihood of reporting any pain relief (OR: 2.10, 95% CI:1.59 to 2.79) compared to those undergoing the traditional approach. In addition, a greater percentage of patients receiving the Kumar Technique experienced at least one month of pain relief compared to the traditional approach (54% vs 40%; z = 3.85, p < 0.001). The occurrence of complications did not significantly vary between the modified (4.1%) and the traditional (3.0%) approaches. Conclusions The Kumar Technique is a modified TFESI approach that allows for improved access to the nerve roots through a more lateral and inferior needle entry point. The analysis supports the benefits of the Kumar Technique with patients experiencing a greater reduction in pain and longer durations of pain relief without increasing the risk of complications.

American Society of Regional Anesthesia and Pain Medicine contrast shortage position statement

The medical field has been experiencing numerous drug shortages in recent years. The most recent shortage to impact the field of interventional pain medicine is that of iodinated contrast medium. Pain physicians must adapt to these changes while maintaining quality of care. This position statement offers guidance on adapting to the shortage.

The Role of Power Doppler Ultrasonography in Caudal Epidural Injection

Background and Objectives: Although the ultrasound-guided technique is used in caudal epidural injections, severe complications can happen if ultrasound cannot identify the occurrence of intravascular injection. To determine intraepidural and intravascular injection during caudal epidural injections, we used power Doppler ultrasonography (PDU) when injecting medications into the epidural space. Materials and Methods: This is a retrospective study that enrolled a total of 277 patients with refractory low back pain or degenerative disc from January 2019 to December 2019. The injectate flow of caudal epidural injections was examined with the assistance of PDU and confirmed by fluoroscopy. Four flow patterns were identified by PDU in our study: the “Earthworm sign,” the “Patch sign,” the ”Tubular sign” and the “Absent flow sign.” The accuracy of PDU in identifying intraepidural and intravascular injections was determined by fluoroscopy images recorded during each injection. Results: We evaluated 277 patients (mean age, 68.6 ± 13.2 years; 106 men). The “Patch sign” showed a sensitivity of 88.76% and a specificity of 80% in predicting epidural injection without intravascular injection. The “Earthworm sign” demonstrated a sensitivity of 70% and a specificity of 100% in detecting intravascular injection. The “Tubular sign” showed a specificity of 100% and a sensitivity of 9.4% in predicting successful epidural injection. The absence of a flow signal showed a sensitivity of 1.87% and a specificity of 90% in predicting successful epidural injection. Conclusions: Ultrasound-guided caudal epidural injection can accurately determine intraepidural and intravascular injections with the assistance of PDU and is thus a good alternative technique to fluoroscopy-guided caudal epidural injection.

Ultrasound-guided cervical selective nerve root injections: a narrative review of literature

BACKGROUND/IMPORTANCE

Ultrasound (US)-guided cervical selective nerve root injections (CSNRI) have been proposed as an alternative to fluoroscopic (FL) -guided injections. When choosing US guidance, the proceduralist should be aware of potential issues confirming vertebral level, be clear regarding terminology, and up to date regarding the advantages and disadvantages of US-guided CSNRI.

OBJECTIVE

Review the accuracy and effectiveness of US guidance in avoiding vascular puncture (VP) and/or intravascular injection (IVI) during CSNRI.

EVIDENCE REVIEW

Queries included PubMed, CINAHL and Embase databases from 2005 to 2019. Three authors reviewed references for eligibility, abstracted data, and appraised quality.

FINDINGS

The literature demonstrates distinct safety considerations and limited evidence of the effectiveness of US guidance in detecting VP and/or IVI. As vascular flow and desired injectate spread cannot be visualized with US, the use of real-time fluoroscopy, and if needed digitial subraction imaging, is indicated in cervical transforaminal epidural injections (CTFEIs). Given the risk of VP and/or IVI, the ability to perform and to retain FL images to document that the procedure was safely conducted is valuable in CTFEIs.

CONCLUSION

US guidance remains to be proven as a non-inferior alternative to FL guidance or other imaging modalities in the prevention of VP and/or IVI with CTFEIs or cervical selective nerve root blocks. There is a paucity of adequately powered clinical studies evaluating the accuracy and effectiveness of US guidance in avoiding VP and/or IVI. US-guided procedures to treat cervical radicular pain has limitations in visualization of anatomy, and currently with the evidence available is best used in a combined approach with FL guidance.

Fluoroscopically guided lumbar spine interlaminar and transforaminal epidural injections: inadvertent intravascular injection

BACKGROUND

Inadvertent intravascular injection is a rare but catastrophic complication of lumbar epidural injections.

PURPOSE

To determine risk factors for inadvertent intravascular injection in fluoroscopically guided lumbar spine epidural injections.

MATERIAL AND METHODS

A total of 212 patients who presented for lumbar interlaminar or transforaminal injection were prospectively enrolled. Patient demographics, history of surgery, injection side, site and approach, and volume of contrast injected were recorded.

RESULTS

There were 89 (42%) interlaminar and 123 (58%) transforaminal injections. For 36 (17%) patients, there had been surgery at the injected or adjacent lumbar level. There were 25 (12%) inadvertent intravascular injections, with an incidence of 2/93 (2%) for interlaminar and 23/119 (19%) for transforaminal injections. The patients with inadvertent intravascular injection were older (P = 0.017) and had prior surgery at or adjacent to the level of injection (P < 0.0001). Transforaminal approach had a higher intravasation rate than interlaminar injections, both when comparing the entire cohort (P = 0.0001) and only patients without prior surgery (P = 0.01). In multivariable logistic regression analysis, transforaminal injections (odds ratio [OR] 9.77, 95% confidence interval [CI] 2.14-44.6, P = 0.003) and prior surgery at or adjacent to the level of injection (OR 5.71, 95% CI 2.15-15.15, P < 0.001) were independently associated with increased risk of inadvertent intravascular injections.

CONCLUSION

Inadvertent intravascular injection occurred in 12% of our lumbar injection cohort and is more common with transforaminal injections, in older patients, and with prior lumbar surgery at or adjacent to the level of injection.

Comparison between anteroposterior and oblique "Scotty dog" approach during S1 transforaminal epidural steroid injection: A randomized controlled trial

BACKGROUND

Traditionally, S1 transforaminal epidural steroid injection (TFESI) has been performed using an anteroposterior (AP) fluoroscopic view. In 2007, the oblique "Scotty dog" (OS) approach was introduced as an alternative technique. We compared passage time of the needle into S1 foramen (Tf) between the anteroposterior (AP) and oblique "Scotty dog" (OS) approach during S1 TFESI.

METHODS

In this prospective randomized controlled trial, seventy patients scheduled S1 TFESI were randomly allocated into AP or OS groups. In the AP group, a slight cephalad-caudad tilt was used. In the OS group, the C-arm was rotated ipsilateral oblique degrees to view the S1 Scotty dog. Both groups received injection of steroid mixed with local anesthetics. We measured the passage time of the needle into S1 foramen (Tf), primary outcome, and total procedure time (Tt) between the groups. We also recorded presence of intravascular injection, patients-assessed pain relief for one month and complications.

RESULTS

The Tf and Tt were shorter in the OS than in the AP group (24.4 ± 24.0 s vs 47. 8 ± 53.2seconds; 93.3 ± 35.0 seconds vs 160.0 ± 98.7 seconds, P < .001, both). Incidence of intravascular injection (AP, 8 [22.8%]; OS, 4 [11.4%], P = .205), pain score, and complication rates were not statistically different between the two groups. In logistic regression analysis, the body mass index (BMI) was a risk factor for longer Tt (odds ratio [OR] = 1.27, 95% CI: 1.02-1.58, P = .030).

CONCLUSION

The passage time of the needle into S1 foramen was shorter in OS approach and the OS approach reduced the procedure time compared with the AP approach during S1 TFESI. The practitioners should note that procedure time can be prolonged in obese patients.

Technical challenges of performing S1 root block: role for double needle and multilevel needle technique

Introduction

S1 root block is performed for pain in the lower limbs due to S1 nerve root inflammation at the L5/S1 disc level or compression in the lateral recess. We often note anterior or posterior spread of contrast away from the L5/S1 disc through an anatomically appropriate needle tip placement. We frequently encounter vascular spread when performing S1 root blocks, and the reported incidence varies between 10.4% and 27.8%. There is no clear strategy published to manage these challenges. In such clinical scenarios, we propose a double needle and/or a multilevel needle technique.

Case

A 39-year-old male presented with radicular pain in the left S1 distribution which matched the magnetic resonance imaging (MRI) scan findings and thus he was listed for a left S1 root block. A 22G needle was placed at the S1 level and upon injecting the contrast, vascular spread and anterior and distal spread along the nerve root were noted and the contrast did not reach the site of the pathology, the L5/S1 disc. The contrast continued to spread anteriorly despite withdrawing the needle. A second needle was placed medial and inferior to the first needle and the contrast spread now was adequate, that is, towards the L5/S1 disc and thus the injection was accomplished in a safe and satisfactory manner without needing to reschedule the procedure.

Conclusion

Double needle technique can assist in overcoming problems encountered when performing an S1 root block. The alternatives could be the multilevel technique or to reschedule the procedure or consider a less optimal technique such as a caudal or a lumbar interlaminar epidural. In this technical report, we have highlighted various intervention options to mitigate such challenges and included a flow diagram to assist in decision-making. We have also discussed the possibility of altering the consent to accommodate the changes to the planned procedure.

Differential rates of intravascular uptake and pain perception during lumbosacral epidural injection among adults using a 22-gauge needle versus 25-gauge needle: a randomized clinical trial

Background

Inadvertent intravascular injection has been suggested as the most probable mechanism behind serious neurological complications during transforaminal epidural steroid injections. Authors believe a smaller gauge needle may lead to less intravascular uptake and less pain. Theoretically, there is less chance for a smaller gauge needle to encounter a blood vessel during an injection compared to a larger gauge needle. Studies have also shown smaller gauge needle to cause less pain. The aim of the study was to quantify the difference between a 22-gauge needle and 25-gauge needle during lumbosacral transforaminal epidural steroid injection in regards to intravascular uptake and pain perception.

Methods

This was a prospective single blind randomized clinical trial performed at outpatient spine practice locations of two academic institutions. One hundred sixty-two consecutive patients undergoing lumbosacral transforaminal epidural injections from February 2018 to June 2019 were recruited and randomized to each arm of the study – 84 patients were randomized to the 22-gauge needle arm and 78 patients to 25-gauge arm. Each transforaminal injection level was considered a separate incidence, hence total number of incidence was 249 (136 in 22-gauge arm and 113 in 25-gauge arm). The primary outcome measure was intravascular uptake during live fluoroscopy and/or blood aspiration. The secondary outcome measure was patient reported pain during the procedure on the numerical rating scale.

Results

Fisher exact test was used to detect differences between 2 groups in regards to intravascular uptake and paired t-tests were used to detect differences in pain scores. The incidence of intravascular uptake for a 22-gauge needle was 5.9% (95% confidence interval: 1.9 to 9.8%) and for a 25-gauge needle, 7.1% (95% confidence interval: 2.4 to 11.8%) [p = 0.701]. Average numerical rating scale scores during the initial needle entry for 22-gauge and 25-gauge needle was 3.46 (95% confidence interval: 2.94 to 3.98) and 3.13 (95% confidence interval: 2.57 to 3.69) respectively [p = 0.375].

Conclusions

The study showed no statistically significant difference in intravascular uptake or pain perception between a 22-gauge needle and 25-gauge needle during lumbosacral transforaminal epidural steroid injections.

Trial registration

ClinicalTrials.gov NCT04350307. Registered 4/17/2020. (Retrospectively registered).

The Effectiveness of Lumbar Transforaminal Injection of Steroid for the Treatment of Radicular Pain: A Comprehensive Review of the Published Data

Objective

To determine the effectiveness of lumbar transforaminal injection of steroid for the treatment of radicular pain.

Design

Comprehensive systematic review.

Outcome Measures

The primary outcome of interest was the proportion of individuals with reduction of pain by ≥50%. Additional outcomes of interest were a more-than-two-point reduction in pain score, patient satisfaction, functional improvement, decreased use of pain medication, and avoidance of spinal surgery.

Results

For patients with disc herniations, using the criterion of ≥50% reduction in pain, success rates across included studies (range) were 63% (58–68%) at one month, 74% (68–80%) at three months, 64% (59–69%) at six months, and 64% (57–71%) at one year. For patients with lumbar spinal stenosis, success rates across included studies (range) were 49% (43–55%) at one month, 48% (35–61%) at three months, 43% (33–53%) at six months, and 59% (45–73%) at one year, but there was a lack of corroboration from appropriately controlled studies.

Conclusions

There is strong evidence that lumbar transforaminal injection of steroids is an effective treatment for radicular pain due to disc herniation. There is a lack of high-quality evidence demonstrating their effectiveness for the treatment of radicular pain due to spinal stenosis, though small studies suggest a possible benefit. Lumbar transforaminal injection of nonparticulate steroids is as effective as injections with particulate steroids.

Effect of needle type on intravascular injection in transforaminal epidural injection: a meta-analysis

Background

Lumbosacral transforaminal epidural injection (TFEI) is an effective treatment for spinal disease. However, TFEI may have several types of complications, some of which can be attributed to intravascular injection. We reviewed studies to compare the intravascular injection rate among different needle types.

Methods

We searched the literature for articles on the intravascular injection rate among different needle types used in TFEI. The search was performed using PubMed, MEDLINE, the Cochrane Library, EMBASE, and Web of Science.

Results

A total of six studies comprising 2359 patients were identified. Compared with the Quincke needle, the Whitacre needle reduced the intravascular injection rate (OR = 0.57, 95% CI = [0.44-0.73], P < 0.001). However, compared with the Quincke needle, the Chiba needle did not reduce the intravascular injection rate (OR = 0.80, 95% CI = [0.44-1.45], P = 0.46). In one study, the intravascular injection rate using a blunt-tip needle was lower than that using a sharp needle. In another study, the Whitacre and the blunt-tip needle have similar intravascular injection rates, while, the catheter-extension needle showed a reduced intravascular injection rate.

Conclusions

This meta-analysis showed that the Whitacre needle reduced the intravascular injection rate as compared with the Quincke needle, but failed to establish that the Chiba needle can decrease the intravascular injection rate in TFEI. Moreover, the blunt-tip needle can reduce the intravascular injection rate compared with the Quincke needle, and the catheter-extension needle can reduce the intravascular injection rate compared with the Whitacre and the blunt-tip needle.

Spontaneous Intracranial Hypotension: Imaging in Diagnosis and Treatment

This article reviews the role of imaging in the diagnosis, management, and treatment of spontaneous intracranial hypotension (SIH). SIH is a debilitating and often misdiagnosed condition caused by either a spinal cerebrospinal fluid (CSF) leak or a CSF to venous fistula. This pathologic condition is identified and localized via spinal imaging, including computed tomographic (CT) myelography, dynamic myelography, dynamic (ultrafast) CT myelography, MR imaging, or MR myelography with intrathecal gadolinium. Treatment of SIH involves conservative measures, surgery, or imaging-guided epidural blood patching.

Transforaminal epidural steroid injection can result in further neurological injury in a patient with severe foraminal stenosis and nerve impingement

Background:

Chronic low back pain (LBP) is highly prevalent and costly in our society. The use of epidural steroid injections (ESIs) for the treatment of radicular LBP is very widespread and continues to rise. The most popular injection is the lumbar/sacral transforaminal epidural steroid injection (TFESI). Here, we present a serious neurological complication resulting from such a TFESI that was only reversed by timely neurosurgical intervention.

Case Description:

A 49-year-old male presented with a 5-year history of progressive neurogenic claudication and right lower extremity pain/radiculopathy. He had previously received multiple lumbar ESIs and other conservative therapy. Due to a recent exacerbation of his radiculopathy associated with MRI-documented lumbosacral spondylosis, he underwent a right L5/S1 TFESI under fluoroscopic guidance. This resulted in acute right lower extremity weakness accompanied by a right-sided foot drop and sphincter dysfunction. Although the follow-up MRI was noncontributory, the EMG showed L5/S1 denervation, and the patient underwent an L4–5, L5–S1 laminectomy with discectomies at the L4–5 and L5–S1 levels. Immediately after the surgery, the patient's weakness and sensory deficits improved. Two years later, the patient continued to do well without evidence of recurrence of signs or symptoms of lumbosacral radiculopathy.

Conclusion:

Patients should be counseled about the risk and benefits of TFESI. Surgical treatment may be warranted in patients who develop acutely progressive worsening following these non-FDA (Food/Drug Administration) approved injections.

Safe Use of Epidural Corticosteroid Injections: Recommendations of the WIP Benelux Work Group

BACKGROUND

Epidural corticosteroid injections are used frequently worldwide in the treatment of radicular pain. Concerns have arisen involving rare major neurologic injuries after this treatment. Recommendations to prevent these complications have been published, but local implementation is not always feasible due to local circumstances, necessitating local recommendations based on literature review.

METHODS

A work group of 4 stakeholder pain societies in Belgium, The Netherlands, and Luxembourg (Benelux) has reviewed the literature involving neurological complications after epidural corticosteroid injections and possible safety measures to prevent these major neurologic injuries.

RESULTS

Twenty-six considerations and recommendations were selected by the work group. These involve the use of imaging, injection equipment particulate and nonparticulate corticosteroids, epidural approach, and maximal volume to be injected.

CONCLUSION

Raising awareness about possible neurological complications and adoption of safety measures recommended by the work group aim at reducing the risks for these devastating events.

The influence of epidural catheter on the incidence of intravascular injection during caudal block

OBJECTIVE

The aim of this study was to analyze the influence of epidural catheters on the incidence of intravascular injection and to identify possible predictors of intravascular injection in patients undergoing a caudal block using fluoroscopy.

METHODS

A total of 154 patients scheduled to receive a caudal block were randomized into group N (those without epidural catheter) or group C (those with epidural catheter). Demographic and clinical data were recorded and analyzed.

RESULTS

The incidence of intravascular injection was 15.6% in group N, 6.5% in group C, and 11.0% overall, without statistical differences between the two groups (P = 0.105). Univariate analysis revealed that blood at hub (P = 0.047) and positive aspiration test (P = 0.045) were more frequently observed in group N than in group C. Quality of analgesia was significantly higher in group C than in group N (P = 0.029). Multivariate analysis identified older age (P = 0.024), blood at hub (P = 0.003), and positive aspiration test (P = 0.001) as predictors of intravascular injection.

CONCLUSIONS

In this study, while the incidence of intravascular injection during caudal blocks was less frequent with epidural catheter use, it was not statistically significant. However, a caudal block using an epidural catheter provided a lower incidence of blood at hub, fewer positive aspiration tests, and superiority in pain improvement.

Image and Contrast Flow Pattern Interpretation for Attempted Epidural Steroid Injections

Fluoroscopically guided, contrast-enhanced epidural steroid injections (ESIs) are frequently performed for radicular symptoms. Interventionalists performing these procedures should have a thorough and detailed understanding of spinal anatomy to safely and effectively deliver the desired injectate to the targeted site. Being able to differentiate epidural from nonepidural contrast flow is vital as is recognizing flow to undesired locations. This article summarizes the characteristics that distinguish between ideal epidural flow patterns and nonideal subarachnoid, intradural, and other suboptimal contrast flow patterns. Recognizing these patterns is essential for safe and successful ESIs and to prevent avoidable complications.

Descriptive Cadaveric Study Comparing the Accuracy of Ultrasound Versus Fluoroscopic Guidance for First Sacral Transforaminal Injections: A Comparison Study

BACKGROUND

Ultrasound is rarely used for guiding lumbosacral epidural steroid injections due to its technical limitations. For example, sonographic imaging lacks the ability to confirm epidural spread and identify vascular uptake. The perceived risk that these limitations pose to human subjects has precluded any large scale clinical trials to date.

OBJECTIVE

To compare the accuracy of ultrasound versus fluoroscopic guidance for first sacral transforaminal epidural injections.

DESIGN

Cadaveric comparative study using dichotomous outcomes.

SETTING

A fluoroscopy suite and anatomic laboratory at an academic medical center.

SUBJECTS

Four unembalmed adult human cadavers with no history of spinal surgery.

METHODS

Eight sites were injected twice by one interventionalist, using fluoroscopic and ultrasound guidance. In the fluoroscopy arm, contrast spread was assessed using computed tomography. In the ultrasound arm, latex spread was assessed using gross anatomic dissection. Any visible evidence of epidural spread constituted a positive result.

MAIN OUTCOME MEASUREMENTS

Comparison of the success of obtaining epidural contrast flow was the primary outcome measure. Secondary outcome measures included average duration, rate of intravascular uptake, and quantity of intravascular uptake.

RESULTS

All injections performed in both the ultrasound arm and the fluoroscopy arm had positive epidural spread. The average duration was 3.03 minutes with fluoroscopy and 4.76 minutes with ultrasound. The rate of intravascular uptake was 37.5% with fluoroscopy and 50% with ultrasound. Within the ultrasound arm, greater intravascular spread and duration variability were recorded.

CONCLUSION

Although ultrasonography can provide reliable image guidance for cannulating the first sacral foramen in cadavers, it would have limited clinical utility due to its inability to visualize relevant neurovascular structures deep to the osseus roof and exclude intravascular uptake.

LEVEL OF EVIDENCE

IV.

Spinal Injections for Pain Management

Image-guided spinal injection is commonly performed in symptomatic patients to decrease pain severity, confirm the pain generator, and delay or avoid surgery. This article focuses on the radiologist as spine interventionist and addresses the following four topics relevant to the radiologist who performs corticosteroid injections for pain management: (a) the rationale behind corticosteroid injection, (b) the interaction with patients, (c) the role of imaging in procedural selection and planning, and (d) the pearls and pitfalls of fluoroscopically guided injections. Factors that contribute to the success of a pain management service include communication skills and risk mitigation. A critical factor is the correlation of clinical symptoms with magnetic resonance (MR) imaging findings. Radiologists can leverage their training in MR image interpretation to distinguish active pain generators in the spine from incidental abnormalities. Knowledge of fluoroscopic anatomy and patterns of contrast material flow guide the planning and execution of safe and effective needle placement. ^© RSNA, 2016 Online supplemental material is available for this article.

Intraforaminal Location of Thoracolumbar Radicular Arteries Providing an Anterior Radiculomedullary Artery Using Flat Panel Catheter Angiotomography

BACKGROUND AND PURPOSE

Flat panel catheter angiotomography performed during the selective injection of intersegmental arteries offers a multiplanar assessment of the intraforaminal course of the radicular arteries providing an anterior radiculomedullary artery. Injury of anterior radiculomedullary arteries during transforaminal epidural steroid injections can result in spinal cord damage. Evaluations of the intraforaminal location of these arteries have so far been limited to anteroposterior views or the examination of cadaveric material. This study documents the in vivo intraforaminal location of thoracolumbar arteries providing an anterior radiculomedullary artery with flat panel catheter angiotomography.

MATERIALS AND METHODS

Ninety-four flat panel catheter angiotomography acquisitions obtained during the selective injection of intersegmental arteries providing an anterior radiculomedullary artery were reviewed. Measurements obtained from sagittal reconstructions were converted into a scatterplot visualization. Patients' age, sex, and side and level of the injection were recorded.

RESULTS

The location of radicular arteries could be ascertained in 78 of 94 flat panel catheter angiotomography acquisitions (33 women and 45 men, 22-82 years of age). Fifty-three acquisitions (67.9%) were on the left side, and 25 (32.1%), on the right, between T2 and L3. The arteries were found in the anterosuperior quadrant of the neural foramen in 75 cases (96.2%), in the posterosuperior quadrant in 2 cases (2.6%), and in the anteroinferior quadrant in 1 case (1.3%). None were located in the posteroinferior quadrant. No differences in location were observed with age, sex, side of injection, or vertebral level.

CONCLUSIONS

Avoiding needle placement in the superior half of the neural foramen, specifically the anterosuperior quadrant, can reduce the risk of spinal cord injury during transforaminal epidural steroid injection.

Comparison of Incidences of Intravascular Injection between Medial and Lateral Side Approaches during Traditional S1 Transforaminal Epidural Steroid Injection

Purpose. Intravascular injection rates are higher during traditional S1 transforaminal epidural steroid injection (TFESI) compared with lumbar transforaminal injection. We compared the incidences of intravascular injection between the medial and lateral approaches to the S1 foramen during S1 TFESI. Materials and Methods. A total of 139 patients underwent one or more TFESIs (170 total injections). The patients received S1 TFESI by either medial or lateral side of S1 foramen under fluoroscopic anteroposterior view using digital subtraction method. The intravascular injection rates, epidural spread patterns, and contrast volumes required to reach the superior aspect of the L5-S1 intervertebral disc (SIVD) were compared between groups. Results. Intravascular injection rates during S1 TFESI were significantly lower in the medial approach compared with the lateral approach patients (4.9% versus 38.6%, resp., P < 0.001). The medial approach group had more epidural spread to the L5-S1 SIVD than the lateral group (82.1% versus 58.8%, resp.); lower contrast volume amounts were required to extend the L5-S1 SIVD (1.46 ± 0.48 versus 1.90 ± 0.62, resp.). Conclusion. During S1 TFESI, approaching the needle towards the medial part of the S1 foramen may reduce intravascular injection risk.

Safety of Epidural Corticosteroid Injections

BACKGROUND AND OBJECTIVE

Epidural corticosteroid injections (ESIs) have been used for several decades and now represent the most common intervention performed for the management of back pain with a radicular component. However, several reports have presented devastating complications and adverse effects, which fuelled concerns over the risk versus clinical effectiveness. The authors offer a comprehensive review of the available literature and analyse the data derived from studies and case reports.

METHODS

Studies were identified by searching PubMed MEDLINE, Ovid MEDLINE, EMBASE, Scopus, Google Scholar and the Cochrane Library to retrieve all available relevant articles. Publications from the last 20 years (September 1994 to September 2014) were considered for further analysis. Studies selected were English-language original articles publishing results on complications related to the technique used for cervical and lumbar ESIs. The studies had to specify the approach used for injection. All studies that did not fulfil these eligibility criteria were excluded from further analysis.

RESULTS

Overall, the available literature supports the view that serious complications following injections of corticosteroid suspensions into the cervical and lumbar epidural space are uncommon, but if they occur they can be devastating.

CONCLUSIONS

The true incidence of such complications remains unclear. Direct vascular injury and/or administration of injectates intra-arterially represent a major concern and could account for the vast majority of the adverse events reported. Accurate placement of the needle, use of a non-particulate corticosteroid, live fluoroscopy, digital subtraction angiography, and familiarisation of the operator with contrast patterns on fluoroscopy should minimise these risks. The available literature has several limitations including incomplete documentation, unreported data and inherent bias. Large registries and well-structured observational studies are needed to determine the true incidence of adverse events and address the safety concerns.

Extraforaminal needle tip position reduces risk of intravascular injection in CT-fluoroscopic lumbar transforaminal epidural steroid injections

BACKGROUND

Lumbar transforaminal epidural steroid injection is a common and effective tool for managing lumbar radicular pain, although accidental intravascular injection can rarely result in paralysis. The purpose of this study is to determine the safest needle tip position for computed tomography (CT)-guided lumbar transforaminal epidural steroid injections as determined by incidence of intravascular injection.

METHODS

Three radiologists, in consensus, reviewed procedural imaging for consecutive CT-fluoroscopic lumbar transforaminal epidural steroid injections performed during a 16-month period. Intravascular injections were identified and categorized by needle tip position, vessel type injected, intravascular injection volume and procedural phase containing the intravascular injection. Pearson chi-square and logistic regression testing were used to assess differences between groups, as appropriate.

RESULTS

Intravascular injections occurred in 9% (52/606) of injections. The intravascular injection rate was significantly lower (P<0.001) for extraforaminal needle position (0%, 0/109) compared to junctional (8%, 27/319) and foraminal (14%, 25/178) needle tip positions. Of the intravascular injections, 4% (2/52) were likely arterial, 35% (18/52) were likely venous, and 62% (32/52) were indeterminate for vessel type injected. 46% (24/52) of intravascular injections were large volume, 33% (17/52) were small volume, and 21% (11/52) were trace volume. 56% (29/52) of intravascular injections occurred with the contrast trial dose, 29% (15/52) with the steroid/analgesic cocktail, and 15% (8/52) with both.

CONCLUSIONS

An extraforaminal needle position for CT-fluoroscopic lumbar transforaminal epidural steroid injections decreases the risk of intravascular injection and therefore may be safer than other needle tip positions.

Detection of Intravascular Injection During Lumbar Medial Branch Blocks: A Comparison of Aspiration, Live Fluoroscopy, and Digital Subtraction Technology

BACKGROUND CONTEXT

Medial branch blocks may have unrecognized vascular uptake potentially resulting in false- negative results.

PURPOSE

To determine the rate of unintended vascular injection of contrast medium during medial branch blocks (MBB) with digital subtraction (DS) technology in the context of negative vascular uptake as determined by live fluoroscopy.

STUDY DESIGN/SETTING

Prospective Study in an academic medical center.

PATIENT SAMPLE

344 consecutive MBBs in 80 subjects.

OUTCOME MEASURES

The presence of vascular flow as determined by live fluoroscopy and DS technology.

METHODS

Unintended vascular injection of contrast medium was determined on 344 consecutive MBBs in 84 subjects, first using live fluoroscopy followed by DS. If live fluoroscopy initially detected vascular uptake, the needle was repositioned until no vascular flow was detected. Once no vascular uptake was confirmed by live fluoroscopy, a contrast medium was then injected while being visualized with DS to again assess the presence or absence of vascular flow undetected by live fluoroscopy.

RESULTS

Live fluoroscopy revealed inadvertent vascular uptake in 38 of the 344 blocks [11% (95% CI 8.0-15%)]. DS uncovered an additional 27 of the 344 blocks [7.8% (95% CI 5.3-11.4%)] with evidence of vascular uptake that were not detected with conventional live fluoroscopy.

CONCLUSION

DS enhances the ability to detect inadvertent vascular flow during medial branch blocks. This study demonstrates that standard live fluoroscopy can miss a small percentage of cases with unintentional vascular uptake during MBB when compared with DS and may contribute to occasional false-negative responses.

The Incidence of Intradiscal, Intrathecal, and Intravascular Flow During the Performance of Retrodiscal (Infraneural) Approach for Lumbar Transforaminal Epidural Steroid Injections

BACKGROUND

Lumbar transforaminal epidural steroid injections (TFESIs) are often used in the treatment of radicular pain. In light of safety concerns, many practitioners have proposed adopting the retrodiscal (infraneural) approach with the needle tip positioned into Kambin's triangle. With this technique, the needle may inadvertently be directed too far ventrally and enter the intervertebral disc. In addition, the risk of subarachnoid or subdural extra-arachnoid injection may be higher with this technique as well.

OBJECTIVE

To determine the incidence of inadvertent intradiscal, intrathecal, and vascular injections during the performance of retrodiscal TFESI.

STUDY DESIGN

Retrospective review

METHODS

Retrospective review of all retrodiscal approach TFESIs performed from July 2012 to August 2014 by two of the authors (DL and SH).

RESULTS

A total of 257 retrodiscal transforaminal injections were performed. There were no neurologic complications. There were no cases of discitis. Inadvertent intradiscal injections occurred in 12/257 injections, 4.7% (95% CI 2.1-7.3%). Intrathecal injections occurred in 8/257 injections, 3.1% (95% CI 0.99- 5.23%). Three were subarachnoid (SA), four were subdural extra-arachnoid (SDXA), and one was both SA and SDXA. Vascular injections occurred in 17/257, 6.6% (95% CI 3.6-9.6%).

CONCLUSION

This retrospective review demonstrates that a relatively high rate of inadvertent intradiscal injections occurs in the performance of the retrodiscal approach for TFESI. This has significant implications in terms of the potential risk of disc injury induced by the needle puncture. The high incidence of intrathecal injections may also be of great concern depending upon the injectate delivered.

Comparison of Transforaminal and Parasagittal Epidural Steroid Injections in Patients With Radicular Low Back Pain

BACKGROUND

Epidural steroid injection (ESI), including transforaminal (TF) epidural injections and interlaminar (IL) epidural steroid injections are commonly performed procedures for the management of lumbosacral radicular pain. Parasagittal interlaminar (PIL) approach could enable higher ventral epidural spread, with fewer complications than TF.

OBJECTIVES

This study aims to compare the effectiveness of PIL and TF ESI in relieving the pain and disability of patients with lumbosacral pain.

PATIENTS AND METHODS

This prospective study enrolled 64 patients, aged between 18 to 75 years, with a diagnosis of low back pain and unilateral lumbosacral radicular pain. The patients were randomized to receive fluoroscopically guided epidural injection, through either the PIL or TF approach. Patients were evaluated for effective pain relief [numerical rating scale (NRS) < 3] by 0 - 10 numeric rating scale (NRS) and functional improvement by the Oswestry Disability Index (ODI).

RESULTS

Effective pain relief [numeric rating scale (NRS) < 3] was observed in 77.3% (95% CI: 67‒90.5%) of patients in PIL group and 74.2% (95% CI: 62.4 - 89.4%) of patients in the TF group (P = 0.34), at 4 weeks. Mean NRS score was not significantly different between the PIL group compared to the TF group, at 4 weeks (P = 0.19). Number of patients with improved disability (measured by ODI < 20%) was not significantly different in PIL group (78% of cases) compared to the TF group (76% of cases), at 4 weeks (P = 0.21). There were no adverse effects observed in any of our patients.

CONCLUSIONS

The PIL epidural injection is as effective as TF epidural injection in improving pain and functional status, in patients with chronic lumbosacral low back pain, due to disc degeneration.

Location of Radicular Spinal Arteries in the Lumbar Spine from Analysis of CT Angiograms of the Abdomen and Pelvis

OBJECTIVE

Reports of catastrophic neurologic injuries following lumbar transforaminal epidural steroid injections are rare but serious potential complications. The traditional method of performing lumbar transforaminal epidural steroid injections is in the "safe triangle" to avoid contact to the spinal nerve. Some authors advocate an alternative approach by placing the needle inferiorly in a region referred to as "Kambin's triangle" to avoid incurring arteries. This study aimed to determine the location of arteries within the L1-L4 intervertebral foramen in vivo, specifically if they lie within or in close proximity to the "safe triangle" or Kambin's triangle using CT angiograms of the abdomen and pelvis.

STUDY DESIGN

The authors retrospectively evaluated the location in vivo of arterial vessels in the intervertebral foramen from L1 to L4 in patients who underwent abdominopelvic CT angiograms for aortic vascular disease. The data were reanalyzed to confirm inter-rater reliability.

RESULTS

Arteries were found in both the safe triangle and Kambin's triangle at a statistically significant rate (P < 0.05).

CONCLUSIONS

In this group of patients, an artery was found in either the safe triangle or in Kambin's triangle frequently, suggesting the location of these arteries can be quite variable. Physicians performing these procedures should use universal precautions to avoid inadvertent injection into the lumbar spinal arteries and minimize potential complications regardless of the approach.

Ventral epidural filling technique in interlaminar epidural steroid injection

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

To evaluate the safety and efficacy of the ventral epidural filling technique in lumbar interlaminar epidural steroid injection (ESI).

SUMMARY OF BACKGROUND DATA

The ventral epidural space can be a preferred target in ESI because it contains many spinal pain generators. However, there have been few studies regarding the ventral epidural space filling technique in interlaminar ESI.

METHODS

This study involved a retrospective analysis of 150 consecutive patients treated with the ventral epidural filling technique in interlaminar ESI (ventral ESI) and a control cohort of 150 consecutive patients treated with the dorsal epidural filling technique in interlaminar ESI (conventional ESI). The visual analogue scale for leg pain, the visual analogue scale for back pain, and the Oswestry Disability Index were compared at preinjection and 2 weeks, 6 weeks, 6 months, and 1 year postinjection. The groups were compared with regard to repeated injection or surgery within 1 year after the initial procedure. The fluoroscopic time and the procedure-related complications including severe pain (visual analogue scale score>7) during injection, dural puncture (subdural contrast spread), headache, neurological symptoms, and infection were also compared.

RESULTS

There were no significant differences in leg pain, back pain, or Oswestry Disability Index improvement at each visit between the ventral ESI group and the conventional ESI group (all P>0.05). The numbers of repeat injections and surgical procedures were not significantly different between 2 groups (P=0.262 and 0.385, respectively). There were no significant differences in severe pain at injection (P=0.326), dural puncture (P=0.428), headache (P=0.393), neurological symptom (P=0.419), or infection (P=0.500) between the 2 groups. The fluoroscopic time was significantly shorter in ventral than in conventional ESI (P<0.000).

CONCLUSION

The ventral epidural filling technique can be performed safely and more easily during lumbar interlaminar ESI. The clinical results and procedure-related complications with this technique were comparable with those seen with conventional interlaminar ESI.

LEVEL OF EVIDENCE

3.

Incidence of Inadvertent Intravascular Injection during CT Fluoroscopy-Guided Epidural Steroid Injections

BACKGROUND AND PURPOSE

Inadvertent intravascular injection during epidural steroid injection can result in complications and has been investigated previously with conventional fluoroscopy, but not CT fluoroscopy. The purpose of this study was to determine the incidence of intravascular injections recognized during CT fluoroscopy-guided epidural steroid injection.

MATERIALS AND METHODS

We retrospectively reviewed 575 consecutive CT fluoroscopy-guided epidural steroid injections. Procedures were assessed to determine the incidence of intravascular injection. Cases positive for intravascular injection were classified on the basis of anatomic location, distance from the needle tip, washout pattern, and presence of combined epidural and vascular injection. Cases were also graded as either venous or arterial by using a 5-point scale.

RESULTS

Intravascular injection was observed in 26% of cervical transforaminal epidural steroid injections (7/27), 9% of cervical interlaminar epidural steroid injections (4/47), 8% of lumbar transforaminal epidural steroid injections (22/275), and 2% of lumbar interlaminar epidural steroid injections (4/222). Vessels were most commonly identified close to the needle, but in 30% of cases, they were visualized in the anterior paraspinal soft tissues remote from the needle. Washout was most commonly delayed (86%), though rapid washout occurred in 14% of cases. Simultaneous epidural and vascular injections occurred in 32% of cases. Most visualized vessels were venous, but 2 cases were classified as probably arterial.

CONCLUSIONS

Intravascular injections can be detected with CT fluoroscopy. The incidence in our study was similar to that in previous reports using conventional fluoroscopy. Technical factors such as the "double-tap" on CT fluoroscopy following contrast injection, assessment for discordance between injected and visualized contrast volume, and maintenance of an appropriate FOV facilitate the detection of such events.

Incidence of intravascular injection and the spread of contrast media during S1 transforaminal epidural steroid injection by two approaches: anteroposterior vs oblique

The aim of this randomised study was to compare the incidence of intravascular injections during S1 transforaminal epidural steroid injection performed in the anteroposterior and oblique views. We also compared epidural spread patterns of contrast media, which included 201 injections at the S1 level. The overall incidence of intravascular injection during S1 transforaminal epidural steroid injection in the anteroposterior view was 29% (29/99), significantly higher than in the oblique view (11%, 11/102, p = 0.001). There were no significant differences between the two groups for epidural spread of contrast media in cases where intravascular injections did not occur (p = 0.77). Performing S1 transforaminal epidural steroid injection in the oblique view rather than the anteroposterior view reduces the risk of intravascular injections.

Comparison of incidence of intravascular injections during transforaminal epidural steroid injection using different needle types

BACKGROUND

Infrequent but serious complications of transforaminal epidural steroid injection (TFESI) occur due to inadvertent intravascular injections. A few studies reported that the different needle types can influence on the occurrences of intravascular incidence in TFESI. This study prospectively evaluated whether short-bevel needle can reduce the incidences of intravascular injection of TFESI compared to long-bevel needles.

METHODS

From March 2013 to December 2013, 239 consecutive patients were enrolled and received 249 fluoroscopically guided TFESI using the classic technique. Confirmation of intravascular spread was done initially with real time fluoroscopy and then with digital subtraction angiography method in a same patient. Injection technique for TFESI was the same for both short-bevel and long-bevel needle types.

RESULTS

The incidences of intravascular injections with the long-bevel and short-bevel needles were 15.0% (21/140) and 9.2% (4/140), respectively. More than half of intravascular injections occurred simultaneously with epidural injections (8.0%, 20/249). There were no statistically significant differences between the long-bevel and the short-bevel needles in the rates of intravascular injections (P = 0.17).

CONCLUSIONS

Short-bevel needles did not demonstrate any benefits in reducing the incidence of intravascular injection.

Aspiration in injections: should we continue or abandon the practice?

Aspiration during any kind of injection is meant to ensure that the needle tip is at the desired location during this blind procedure. While aspiration appears to be a simple procedure, it has generated a lot of controversy concerning the perceived benefits and indications. Advocates and opponents of aspiration both make logically sound claims. However, due to scarcity of available data, there is no evidence that this procedure is truly beneficial or unwarranted. Keeping in view the huge number of injections given worldwide, it is important that we draw attention to key questions regarding aspiration that, up till now, remain unanswered. In this review, we have attempted to gather and present literature on aspiration both from published and non-published sources in order to provide not only an exhaustive review of the subject, but also a starting point for further studies on more specific areas requiring clarification. A literature review was conducted using the US National Institute of Health’s PubMed service (including Medline), Google Scholar and Scopus. Guidelines provided by the World Health Organization, Safe Injection Global Network, International Council of Nursing, Center for Disease Control, US Federal Drug Agency, UK National Health Services, British Medical Association, Europe Nursing and Midwifery Council, Public Health Agency Canada, Pakistan Medical Association and International Organization of Standardization recommendations 7886 parts 1-4 for sterile hypodermics were reviewed for relevant information. In addition, curricula of several medical/nursing schools from India, Nigeria and Pakistan, the US pharmacopeia Data from the WHO Program for International Drug Monitoring network in regard to adverse events as a result of not aspirating prior to injection delivery were reviewed. Curricula of selected major medical/nursing schools in India, Nigeria and Pakistan, national therapeutic formularies, product inserts of most commonly used drugs and other possible sources of information regarding aspiration and injections were consulted as well.

A comparison of the analgesic efficacy of transforaminal methylprednisolone alone and with low doses of clonidine in lumbo-sacral radiculopathy

Background:

Although transforaminal epidural steroid injections under fluoroscopic guidance have become a common mode of treatment of lumbosacral radiculopathy due to herniated disc, the efficacy of steroid with low doses of clonidine has not been compared yet.

Objectives:

Comparison of the analgesic efficacy of methylprednisolone alone and with low doses of clonidine for transforaminal injection in lumbosacral radiculopathy.

Study Design:

A randomized, double-blind trial.

Setting:

This study was performed at the Pain Clinic under the Department of Anaesthesiology, Jawaharlal Nehru Medical College Hospital, Aligarh Muslim University, Aligarh, India.

Methods:

One hundred and eighty ASA grade I and II patients aged between 18 and 55 years were allocated into groups I, II and III to receive methylprednisolone 60 mg alone or methylprednisolone 60 mg with or without low doses of clonidine (0.5 mcg/kg or 1 mcg/kg) as transforaminal epidural injection. Pain relief and patient's satisfaction were evaluated with the global pain scale. Follow-up visits were advised at 1, 2, 4, 6 and 12 weeks and then at 6 months after injection. Associated complications were recorded.

Results:

Maximum pain relief was observed at 2 weeks after injection in all the three groups, with no difference in complication rate among the three groups. The most common complication observed was paresthesia in the nerve distribution. Greater than 60% improvement in pain scores was seen in 40% of the patients in group I, 50% of the patients in group II and 75% of the patients in group III.

Limitations:

This study is limited by the lack of a placebo group.

Conclusion:

Adding 1 mcg/kg clonidine to 60 mg methylprednisolone in transforaminal epidural injections provided better pain relief than 60 mg methylprednisolone with 0.5 mcg/kg clonidine or 60 mg methylprednisolone alone in patients suffering from lumbosacral radiculopathy, with practically no significant side-effects.

Perineural hematoma following lumbar transforaminal steroid injection causing acute-on-chronic lumbar radiculopathy: a case report

INTRODUCTION

Transforaminal epidural steroid injections (TFESI) are commonly performed for the treatment of lumbar herniated nucleus pulposus and lumbosacral radiculopathy. Although rare, documented complications including spinal cord infarction, paraparesis, epidural abscess, paraplegia, and epidural hematoma have been reported. Here, we present a case of perineural hematoma affecting the L4 nerve root resulting in progressive acute-on-chronic lumbar radiculopathy following TFESI.

CASE REPORT

A 72-year-old female presented with 3 months of low back and right anterior thigh pain. She subsequently underwent right L3 and L4 TFESI for physical examination findings concordant with radiographic right foraminal stenosis at L3-4 and L4-5 with L3-4 spondylolisthesis. Over the following week, the patient reported progressive right lower extremity weakness, worsening sensory loss, and ambulatory dysfunction. Examination revealed mild L3/4 myotomal weakness, sensory changes, and areflexia at the right patella. A gadolinium-enhanced MRI was ordered, which showed focal abnormal signal with involvement of the right L4-L5 neuroforamina and extending slightly far laterally, consistent with a small hematoma, affecting the L4 nerve root. Within 2 months, her strength and reflexes normalized and sensory loss diminished following medical management.

DISCUSSION

Although extremely rare, perineural or foraminal hematomas may occur as a serious complication of TFESI, even in the setting of a standardized procedure. Hematoma may cause worsening of symptoms in the acute and subacute phase following TFESI. Further investigation into the etiologies of such injuries is warranted and must be added to the considerations of pain physicians performing these procedures.

20 MHz forward-imaging single-element beam steering with an internal rotating variable-angle reflecting surface: Wire phantom and ex vivo pilot study

Feasibility is demonstrated for a forward-imaging beam steering system involving a single-element 20MHz angled-face acoustic transducer combined with an internal rotating variable-angle reflecting surface (VARS). Rotation of the VARS structure, for a fixed position of the transducer, generates a 2-D angular sector scan. If these VARS revolutions were to be accompanied by successive rotations of the single-element transducer, 3-D imaging would be achieved. In the design of this device, a single-element 20MHz PMN-PT press-focused angled-face transducer is focused on the circle of midpoints of a micro-machined VARS within the distal end of an endoscope. The 2-D imaging system was tested in water bath experiments with phantom wire structures at a depth of 10mm, and exhibited an axial resolution of 66μm and a lateral resolution of 520μm. Chirp coded excitation was used to enhance the signal-to-noise ratio, and to increase the depth of penetration. Images of an ex vivo cow eye were obtained. This VARS-based approach offers a novel forward-looking beam-steering method, which could be useful in intra-cavity imaging.

Ultrasound-guided selective nerve root block versus fluoroscopy-guided transforaminal block for the treatment of radicular pain in the lower cervical spine: a randomized, blinded, controlled study

OBJECTIVES

To compare the short-term effects and advantages of ultrasound-guided selective nerve root block with fluoroscopy-guided transforaminal epidural block for radicular pain in the lower cervical spine through assessment of pain relief, functional improvement, and safety.

METHODS

A total of 120 patients with radicular pain from cervical spinal stenosis or cervical herniated disc were enrolled. All procedures were performed using a fluoroscopy or ultrasound apparatus. The subjects were randomly assigned to either the fluoroscopy (FL) or ultrasound (US) group. The complication frequencies during the procedures, treatment effects, and functional improvement of the nerve root block were compared at 2 and 12 weeks after the procedures.

RESULTS

Verbal Numeric Pain Scale (VNS) improved 2 weeks and 12 weeks after the injections in both groups. Statistical differences were not observed in VNS, Neck Disability Index (NDI), and effectiveness between the groups. In 21 patients at US, vessels were identified at the anterior aspect of the foramen. Eleven patients had a critical vessel at the posterior aspect of the foramen and five patients had on artery continue medially into the foramen, forming, or joining a segmental feeder artery. In both cases, the vessels might well have been in the pathway of the needle correctly positioned under fluoroscopic guidance. Five cases of intravascular injections were observed only in FL without significant difference between the groups.

CONCLUSIONS

The US-guided method may facilitate identifying critical vessels at unexpected locations relative to the intervertebral foramen and avoiding injury to such vessels, which is the leading cause of the reported complications from cervical transforaminal injections. On treatment effect, using either method of epidural injections to deliver steroids for cervical radicular pain, secondary to herniated intervertebral disc or foraminal stenosis, significant improvements in function and pain relief were observed in both groups after the intervention. However, significant difference was not observed between the groups. Therefore, the ultrasound-guided method was shown to be as effective as the fluoroscopy-guided method in pain relief and functional improvement, in addition to the absence of radiation and avoiding vessel injury at real-time imaging.

Conus medullaris syndrome after epidural steroid injection: Case report

Background

Given the risk of paralysis associated with cervical transforaminal injection, is it time to reconsider transforaminal injections of the lumbar spine? Arguments for discontinuing lumbar injections have been discussed in the anesthesia literature, raising concern about the risks of epidural steroid injections (ESIs).

Methods

In a 47-year-old man, paraplegia of the lower extremities developed, specifically conus medullaris syndrome, after he underwent an ESI for recurrent pain. Correct needle placement was verified with epidurography. Immediately after the injection, the patient felt his legs “going dead”; paraplegia of the lower extremities was noted.

Results

An initial magnetic resonance imaging study performed after the patient was transferred to the emergency department was unremarkable. However, a later neurosurgical evaluation showed conus medullaris syndrome, and a second magnetic resonance imaging study showed the conus infarct. We conducted a search of the PubMed database of articles from 2002 to 2011 containing the following keywords: complications, lumbar epidural steroid injection(s), cauda equina syndrome, conus medullaris infarction, spinal cord infarction, spinal cord injury, paralysis, paresis, plegia, paresthesia, and anesthesia.

Conclusions

Summarizing this case and 5 similar cases, we weigh the potential benefits and risks of ESI. Although one can safely assume that this severe, devastating complication is rare, we speculate that its true incidence remains unknown, possibly because of medicolegal implications. We believe that the rarity of this complication should not preclude the continued use of transforaminal ESI; rather, it should be emphasized for discussion with patients during the consent process.