Accuracy of live fluoroscopy to detect intravascular injection during lumbar transforaminal epidural injections

Autonomous Spinal Robotic System for Transforaminal Lumbar Epidural Injections: A Proof of Concept of Study

STUDY DESIGN

Phantom study.

OBJECTIVE

The aim of our study is to demonstrate in a proof-of-concept model whether the use of a marker less autonomous robotic controlled injection delivery system will increase accuracy in the lumbar spine.

METHODS

Ideal transforaminal epidural injection trajectories (bilateral L2/3, L3/4, L4/5, L5/S1 and S1) were planned out on a virtual pre-operative planning software by 1 experienced provider. Twenty transforaminal epidural injections were administered in a lumbar spine phantom model, 10 using a freehand procedure, and 10 using a marker less autonomous spinal robotic system. Procedural accuracy, defined as the difference between pre-operative planning and actual post-operative needle tip distance (mm) and angular orientation (degrees), were assessed between the freehand and robotic procedures.

RESULTS

Procedural accuracy for robotically placed transforaminal epidural injections was significantly higher with the difference in pre- and post-operative needle tip distance being 20.1 (±5.0) mm in the freehand procedure and 11.4 (±3.9) mm in the robotically placed procedure (P < .001). Needle tip precision for the freehand technique was 15.6 mm (26.3 - 10.7) compared to 10.1 mm (16.3 - 6.1) for the robotic technique. Differences in needle angular orientation deviation were 5.6 (±3.3) degrees in the robotically placed procedure and 12.0 (±4.8) degrees in the freehand procedure (P = .003).

CONCLUSION

The robotic system allowed for comparable placement of transforaminal epidural injections as a freehand technique by an experienced provider, with additional benefits of improved accuracy and precision.

Safety of local anesthetics in cervical nerve root injections: a narrative review

Severe neurological adverse events have been reported after fluoroscopically guided cervical nerve root injections. Particulate corticosteroids inadvertently injected intraarterially and iatrogenic vertebral artery trauma have been implicated in these outcomes. This has raised concern for the potential consequences of including local anesthetic with these injections. As a result, some providers have now discontinued the routine administration of local anesthetic with corticosteroid when performing cervical nerve root injections. At present, there is no consensus regarding whether the use of local anesthetic in this context is safe. Here, the current literature is synthesized into a narrative review aiming to clarify current perspectives of the safety of local anesthetics in cervical nerve root injections.

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.

Comparison of Whitacre needle and Chiba needle on the incidence of intravascular injection during caudal epidural injections: A single-blind, randomized clinical consort study

Caudal epidural injection (CEI) is effective for lumbar spinal pain. However, accidental intravascular injection reduces therapeutic efficacy of CEI and leads to fatal complications such as hematoma, and neurologic deficit. Whitacre needle has been reported to be effective for reducing intravascular injection during transforaminal epidural injection, compared with Quincke needle. The bevel of Chiba needle is shorter than that of Quincke needle. In this study we compared Whitacre needle and Chiba needle on incidence of intravascular injection during CEI.This was a single-blind, randomized clinical consort study. After institutional Review Board approval, a total of 164 patients underwent CEI were randomly allocated to one of 2 group (Whitacre needle or Chiba needle group). Intravascular injection was assessed with real-time fluoroscopy. In addition, total procedure time was measured. Data were compared between groups, and P < .05 was consideredstatistically significant.There were no differences between groups in terms of patient demographic and clinical characteristics. There was no significant difference on incidence of intravascular injection between Whitacre and Chiba needle group (11% vs 19.5%, P = .192). However, the procedure time is significantly longer in the Whitacre than Chiba needle group (172.8 ± 53.8 sec vs 147.1 ± 61.1 sec, P = .005).Based on current study, our results indicated that Whitacre needle was not effective to decrease the incidence of intravascular injection during CEI, compared to Chiba needle.

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.

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).

Digital subtraction angiography vs. real-time fluoroscopy for detection of intravascular injection during transforaminal epidural block

Background

Transforaminal epidural block (TFEB) is an effective treatment option for radicular pain. To reduce complications from intravascular injection during TFEB, use of imaging modalities such as real-time fluoroscopy (RTF) or digital subtraction angiography (DSA) has been recommended. In this study, we investigated whether DSA improved the detection of intravascular injection during TFEB at the whole spine level compared to RTF.

Methods

We prospectively examined 316 patients who underwent TFEB. After confirmation of final needle position using biplanar fluoroscopy, 2 mL of nonionic contrast medium was injected at a rate of 0.5 mL/s under RTF; 30 s later, 2 mL of nonionic contrast medium was injected at a rate of 0.5 mL/s under DSA.

Results

Thirty-six intravascular injections were detected for an overall rate of 11.4% using RTF, with 45 detected for a rate of 14.2% using DSA. The detection rate using DSA was statistically different from that using RTF (p=0.004). DSA detected a significantly higher proportion of intravascular injections at the cervical level than at the thoracic (p=0.009) and lumbar (p=0.011) levels.

Conclusion

During TFEB at the whole spine level, DSA was better than RTF for the detection of intravascular injection. Special attention is advised for cervical TFEB, because of a significantly higher intravascular injection rate at this level than at other levels.

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.

Distribution Patterns of Vasculature Around Cervical Nerve Roots

BACKGROUND

To the authors' knowledge, there has not been an ultrasound study of the vulnerable vessels in a C3-7 cervical nerve root block (CNRB).

OBJECTIVES

To evaluate the prevalence of vulnerable vessels around the target of a CNRB at the cervical nerve root of C3-7 levels in a clinical setting.

DESIGN

Retrospective, cross-sectional study.

SETTING

General teaching hospital, rehabilitation unit.

PARTICIPANTS

A total of 104 patients complaining of neck or arm pain with no prior surgical history and who had undergone a CNRB at an outpatient clinic from May 2015 to December 2017 were included.

MAIN OUTCOME MEASUREMENTS

The prevalence of vulnerable vessels as seen on a preprocedure ultrasound scan around the target of a CNRB at the cervical nerve root of C3-7 levels.

RESULTS

Out of 104 cases, the C3 level had 7 blood vessels (8.33%), the C4 level had 14 blood vessels (13.86%), the C5 level had 17 blood vessels (16.35%), the C6 level had 27 blood vessels (25.96%), and the C7 level had 31 blood vessels (29.81%) either at the targeted cervical nerve root or at the site of the imaginary needle's projected pathway to the targeted cervical nerve root.

CONCLUSION

There was a substantial prevalence of vulnerable vessels either at the targeted nerve root or at the site of the needle's projected pathway to the nerve root.

Optical signature of nerve tissue-Exploratory ex vivo study comparing optical, histological, and molecular characteristics of different adipose and nerve tissues

Background

During several anesthesiological procedures, needles are inserted through the skin of a patient to target nerves. In most cases, the needle traverses several tissues—skin, subcutaneous adipose tissue, muscles, nerves, and blood vessels—to reach the target nerve. A clear identification of the target nerve can improve the success of the nerve block and reduce the rate of complications. This may be accomplished with diffuse reflectance spectroscopy (DRS) which can provide a quantitative measure of the tissue composition. The goal of the current study was to further explore the morphological, biological, chemical, and optical characteristics of the tissues encountered during needle insertion to improve future DRS classification algorithms.

Methods

To compare characteristics of nerve tissue (sciatic nerve) and adipose tissues, the following techniques were used: histology, DRS, absorption spectrophotometry, high‐resolution magic‐angle spinning nuclear magnetic resonance (HR‐MAS NMR) spectroscopy, and solution 2D ¹³C‐¹H heteronuclear single‐quantum coherence spectroscopy. Tissues from five human freshly frozen cadavers were examined.

Results

Histology clearly highlights a higher density of cellular nuclei, collagen, and cytoplasm in fascicular nerve tissue (IFAS). IFAS showed lower absorption of light around 1200 nm and 1750 nm, higher absorption around 1500 nm and 2000 nm, and a shift in the peak observed around 1000 nm. DRS measurements showed a higher water percentage and collagen concentration in IFAS and a lower fat percentage compared to all other tissues. The scattering parameter (b) was highest in IFAS. The HR‐MAS NMR data showed three extra chemical peak shifts in IFAS tissue.

Conclusion

Collagen, water, and cellular nuclei concentration are clearly different between nerve fascicular tissue and other adipose tissue and explain some of the differences observed in the optical absorption, DRS, and HR‐NMR spectra of these tissues. Some differences observed between fascicular nerve tissue and adipose tissues cannot yet be explained but may be helpful in improving the discriminatory capabilities of DRS in anesthesiology procedures. Lasers Surg. Med. 50:948–960, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

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.

Impact of Type of Needle on Incidence of Intravascular Injection During Diagnostic Lumbar Medial Branch Block

BACKGROUND AND OBJECTIVES

Intravascular (IV) injection of local anesthetics is a potential cause of false-negative results after lumbar medial branch nerve blockade (L-MBB) performed to diagnose facetogenic back pain. The aim of the present study was to identify the relationship between the needle type and the incidence of IV injection in patients undergoing L-MBB using fluoroscopy with digital subtraction imaging (DSI).

METHODS

In this prospective randomized study, we compared the incidence of IV uptake of contrast medium using the Quincke needle and Whitacre needle under real-time DSI during L-MBB. Clinical and demographic factors associated with the occurrence of IV uptake were also investigated.

RESULTS

In total, 126 patients were randomized into the Quincke needle group (n = 62) and Whitacre needle group (n = 64). Intravascular uptake of contrast medium was observed in 66 (9.8%) of 671 L-MBB procedures under DSI. The incidence of IV uptake was 13.9% (47/338) using the Quincke needle and 5.7% (19/333) using the Whitacre needle. In the multivariate generalized estimating equations analysis, use of a Quincke needle was related to positive IV injection at a 1.898-fold higher rate than was use of a Whitacre needle (95% confidence interval, 1.025-3.516) and a positive aspiration test predicted IV injection at a 21.735-fold higher rate (95% confidence interval, 11.996-52.258).

CONCLUSIONS

Lumbar medial branch nerve blockade using the Quincke needle was associated with a 1.9-fold higher rate of IV injection than was L-MBB using the Whitacre needle under DSI. Although further study is needed to confirm the clinical efficacy, Whitacre needles can be considered to reduce the risk of IV injection during L-MBB.

Safeguards to Prevent Neurologic Complications after Epidural Steroid Injections

Background:

Epidural corticosteroid injections are a common treatment for radicular pain caused by intervertebral disc herniations, spinal stenosis, and other disorders. Although rare, catastrophic neurologic injuries, including stroke and spinal cord injury, have occurred with these injections.

Methods:

A collaboration was undertaken between the U.S. Food and Drug Administration Safe Use Initiative, an expert multidisciplinary working group, and 13 specialty stakeholder societies. The goal of this collaboration was to review the existing evidence regarding neurologic complications associated with epidural corticosteroid injections and produce consensus procedural clinical considerations aimed at enhancing the safety of these injections. U.S. Food and Drug Administration Safe Use Initiative representatives helped convene and facilitate meetings without actively participating in the deliberations or decision-making process.

Results:

Seventeen clinical considerations aimed at improving safety were produced by the stakeholder societies. Specific clinical considerations for performing transforaminal and interlaminar injections, including the use of nonparticulate steroid, anatomic considerations, and use of radiographic guidance are given along with the existing scientific evidence for each clinical consideration.

Conclusion:

Adherence to specific recommended practices when performing epidural corticosteroid injections should lead to a reduction in the incidence of neurologic injuries.

Detection Rate of Intravascular Injections during Cervical Medial Branch Blocks: A Comparison of Digital Subtraction Angiography and Static Images from Conventional Fluoroscopy

Background

The most definitive diagnosis of neck pain caused by facet joints can be obtained through cervical medial branch blocks (CMBBs). However, intravascular injections need to be carefully monitored, as they can increase the risk of false-negative blocks when diagnosing cervical facet joint syndrome. In addition, intravascular injections can cause neurologic deficits such as spinal infarction or cerebral infarction. Digital subtraction angiography (DSA) is a radiological technique that can be used to clearly visualize the blood vessels from surrounding bones or dense soft tissues. The purpose of this study was to compare the rate of detection of intravascular injections during CMBBs using DSA and static images obtained through conventional fluoroscopy.

Methods

Seventy-two patients were included, and a total of 178 CMBBs were performed. The respective incidences of intravascular injections during CMBBs using DSA and static images from conventional fluoroscopy were measured.

Results

A total of 178 CMBBs were performed on 72 patients. All cases of intravascular injections evidenced by the static images were detected by the DSAs. The detection rate of intravascular injections was higher from DSA images than from static images (10.7% vs. 1.7%, P < 0.001).

Conclusions

According to these findings, the use of DSA can improve the detection rate of intravascular injections during CMBBs. The use of DSA may therefore lead to an increase in the diagnostic and therapeutic value of CMBBs. In addition, it can decrease the incidence of potential side effects during CMBBs.

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.

Advantages of digital subtraction angiography during nerve block

Introduction:

Most pain physicians know that fluoroscopy might improve the safety, accuracy, and efficacy of nerve block; however, it is difficult to distinguish the previously administered contrast medium from the injecting contrast medium, and to identify accurate contrast medium diffusion flow in a case of existing radiodensities such as cement and screw. Digital subtraction angiography (DSA) can improve accuracy of nerve blocks.

Case Presentation:

We described our experiences with two successful transforaminal epidural injections and nerve block of two patients with 73 and 68 years of age who were diagnosed as failed back surgery syndrome.

Conclusions:

The advantages of DSA in fluoroscopy-guided transforaminal epidural block and nerve block are identification of the degree of appropriate contrast flow (epidural and nerve root sleeve) and the intravascular administration without overlapping radiodense structures.

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.

Incidence of intravascular insertion in thoracic epidural catheterization by using real time fluoroscopy

BACKGROUND

Epidural analgesia is commonly used to provide several types of pain relief. Although this technique has been widely used with many advantages, currently the complications appear to be increasing. Especially, inadvertent intravascular cannulation and intravascular local anesthetic administration can lead to fatal consequences.

METHODS

Data was collected on 296 patients undergoing elective thoracic or abdominal surgery. Two detection methods were utilized to confirm the epidural intravascular cannulation; flashback and aspiration of indwelling catheter, and injection of a contrast agent through the catheter under fluoroscopy were used to guide the placement of the catheter and to examine the intravascular cannulation.

RESULTS

Epidural intravascular cannulation was reported in 4 out of 296 cases (1.4%), and 1 patient underwent subdural cannulation. Among the 4 cases of epidural intravascular cannulation, two were confirmed by the flashback and aspiration methods, while the remaining cases were only detected by real time fluoroscopy.

CONCLUSIONS

In this study, inadvertent epidural intravascular cannulation occurred by as much as 1.4% of thoracic epidural catheterization. Utilizing real time fluoroscopy in addition to flashback and aspiration can enhance the sensitivity of detection.