Spinal dural and epidural fistulas: role of cone beam CT in diagnosis and treatment

Understanding normal spinal arterial and venous anatomy, and spinal vascular disease, is impossible without flow-based methods. Development of practical spinal angiography led to site-specific categorization of spinal vascular conditions, defined by the 'seat of disease' in relation to the cord and its covers. This enabled identification of targets for highly successful surgical and endovascular treatments, and guided interpretation of later cross-sectional imaging.Spinal dural and epidural arteriovenous fistulas represent the most common types of spinal shunts. Although etiology is debated, anatomy provides excellent pathophysiologic correlation. A spectrum of fistulas, from foramen magnum to the sacrum, is now well-characterized.Most recently, use of cone beam CT angiography has yielded new insights into normal and pathologic anatomy, including venous outflow. It provides unrivaled visualization of the fistula and its relationship with spinal cord vessels, and is the first practical method to study normal and pathologic spinal veins in vivo-with multiple implications for both safety and efficacy of treatments. We advocate consistent use of cone beam CT imaging in modern spinal fistula evaluation.The role of open surgery is likely to remain undiminished, with increasing availability and use of hybrid operating rooms for practical intraoperative angiography enhancing safety and efficacy of complex surgery.

Primary failure of thoracic epidural analgesia: revisited

Primary failure of thoracic epidural analgesia (TEA) remains an important clinical problem, whose incidence can exceed 20% in teaching centers. Since loss-of-resistance (LOR) constitutes the most popular method to identify the thoracic epidural space, the etiology of primary TEA failure can often be attributed to LOR's low specificity. Interspinous ligamentous cysts, non-fused ligamenta flava, paravertebral muscles, intermuscular planes, and thoracic paravertebral spaces can all result in non-epidural LORs. Fluoroscopy, epidural waveform analysis, electrical stimulation, and ultrasonography have been proposed as confirmatory modalities for LOR.The current evidence derived from randomized trials suggests that fluoroscopy, epidural waveform analysis, and possibly electrical stimulation, could decrease the primary TEA failure to 2%. In contrast, preprocedural ultrasound scanning provides no incremental benefit when compared with conventional LOR. In the hands of experienced operators, real-time ultrasound guidance of the epidural needle has been demonstrated to provide comparable efficacy and efficiency to fluoroscopy.Further research is required to determine the most cost-effective confirmatory modality as well as the best adjuncts for novice operators and for patients with challenging anatomy. Moreover, future trials should elucidate if fluoroscopy and electrical stimulation could potentially decrease the secondary failure rate of TEA, and if a combination of confirmatory modalities could outperform individual ones.

Real-time ultrasound guidance versus fluoroscopic guidance in thoracic epidural catheter placement: a single-center, non-inferiority, randomized, active-controlled trial

INTRODUCTION

Fluoroscopy can improve the success rate of thoracic epidural catheter placement (TECP). Real-time ultrasound (US)-guided TECP was recently introduced and showed a high first-pass success rate. We tested whether real-time US-guided TECP results in a non-inferior first-pass success rate compared with that of fluoroscopy-guided TECP.

METHODS

In this single-center, non-inferiority, randomized trial, the primary outcome was the comparison of the first-pass success rate of TECP between real-time US guidance (US group) and fluoroscopic guidance (fluoroscopy group). Secondary outcomes included time to identifying epidural space, procedure time, total number of needle passes, number of skin punctures, final success, and cross-over success.

RESULTS

We randomly assigned 132 patients to the allocated groups. The difference in the first-pass success rate between the groups did not exceed the non-inferiority margin of 15% (US group: 66.7% vs fluoroscopy group: 68.2%; difference -1.5%, 95% exact CI: -14.9% to 11.9%). The difference in the final success rate also did not differ between the groups (98.5% vs 100.0%; difference -1.5%, 95% exact CI: -4.0% to 1.0%). The time to identifying epidural space (45.6 (34-62) vs 59.0 (42-77) s, p=0.004) and procedure time (39.5 (28-78) vs 112.5 (93-166) s, p<0.001) were significantly shorter in the US group.

CONCLUSIONS

Real-time US guidance provided a non-inferior success rate and shorter time spent on preparation and procedure compared with fluoroscopic guidance in TECP.

TRIAL REGISTRATION NUMBER

KCT0006521.

Evaluation of a modified ultrasound-assisted technique for mid-thoracic epidural placement: a prospective observational study

BACKGROUND

Although mid-thoracic epidural analgesia benefits patients undergoing major surgery, technical difficulties often discourage its use. Improvements in technology are warranted to improve the success rate on first pass and patient comfort. The previously reported ultrasound-assisted technique using a generic needle insertion site failed to demonstrate superiority over conventional landmark techniques. A stratified needle insertion site based on sonoanatomic features may improve the technique.

METHODS

Patients who presented for elective abdominal or thoracic surgery requesting thoracic epidural analgesia for postoperative pain control were included in this observational study. A modified ultrasound-assisted technique using a stratified needle insertion site based on ultrasound images was adopted. The number of needle passes, needle skin punctures, procedure time, overall success rate, and incidence of procedure complications were recorded.

RESULTS

One hundred and twenty-eight subjects were included. The first-pass success and overall success rates were 75% (96/128) and 98% (126/128), respectively. In 95% (122/128) of patients, only one needle skin puncture was needed to access the epidural space. The median [IQR] time needed from needle insertion to access the epidural space was 59 [47-122] seconds. No complications were observed during the procedure.

CONCLUSIONS

This modified ultrasound-assisted mid-thoracic epidural technique has the potential to improve success rates and reduce the needling time. The data shown in our study may be a feasible basis for a prospective study comparing our ultrasound-assisted epidural placements to conventional landmark-based techniques.

Confirming identification of the epidural space: a systematic review of electric stimulation, pressure waveform analysis, and ultrasound and a meta-analysis of diagnostic accuracy in acute pain

To review the use of epidural electric stimulation test, pressure waveform analysis, and ultrasound assessment of injection as bedside methods for confirming identification of the epidural space in adults with acute pain, the PubMed database was searched for relevant reports between May and August 2022. Studies reporting diagnostic accuracy with conventional Touhy needles and epidural catheters were further selected for meta-analysis. Sensitivity and specificity were estimated using univariate logistic regression for electric stimulation and pressure analysis, and pooling of similar studies for ultrasound. Risk of bias and applicability was assessed using QUADAS-2. For electric stimulation, pressure waveform analysis, and ultrasound, respectively 35, 22, and 28 reports were included in the review and 9, 9, and 7 studies in the meta-analysis. Electric stimulation requires wire-reinforced catheters and an adequate nerve stimulator, does not reliably identify intravascular placement, and is affected by local anaesthetics. Sensitivity was 95% (95% CI 93-96%, N = 550) and specificity unknown (95% CI 33-94%, N = 44). Pressure waveform analysis is unaffected by local anaesthetics, but does not identify intravascular nor intrathecal catheters. Sensitivity was 90% (95% CI 72-97%, N = 694) and specificity 88% (95% CI 78-94%, N = 67). B-mode, M-mode and doppler ultrasound may be challenging, and data is still limited. Risk of bias was significant and accuracy estimates must be interpreted with caution. Electric stimulation and pressure waveform analysis seem clinically useful, although they must be interpreted cautiously. In the future, clinical trials in patients with difficult anatomy will likely be most useful. Ultrasound requires further investigation.

Contralateral oblique view can prevent dural puncture in fluoroscopy-guided cervical epidural access: a prospective observational study

INTRODUCTION

Although the contralateral oblique (CLO) view at 50°±5° is clinically useful for cervical epidural access, no previous studies have confirmed its safety. This prospective observational study was conducted to assess the safety profile, including the risk of dural puncture, in fluoroscopically guided cervical epidural access using the CLO view.

METHODS

In cervical epidural access using the CLO view, the incidence of dural puncture was investigated as the primary outcome. Other intraprocedural complications, including intravascular entry, subdural entry, spinal cord injury and vasovagal injury, and postprocedural complications were investigated as secondary outcomes. Procedural variables including first-pass success, final success, needling time, total number of needle passes and false loss of resistance (LOR) were evaluated.

RESULTS

Of the 393 patients who underwent cervical interlaminar epidural access were included for analysis, no instances of dural puncture or spinal cord injury were observed. The incidence of intravascular entry, vasovagal reaction and subdural entry were 3.1%, 0.5% and 0.3%, respectively. All procedures were successfully performed, with 85.0% of first-pass success rate. The mean needling time was 133.8 (74.9) s. The false-positive and false-negative LOR rates were 8.2% and 2.0%, respectively. All needle tips were visualized clearly during the procedure.

CONCLUSIONS

The fluoroscopy-guided CLO view at 50°±5° avoided dural puncture or spinal cord injury and decreased the incidence of false LOR during cervical epidural access with a paramedian approach.

TRIAL REGISTRATION NUMBER

NCT04774458.

Ultrasound: A novel alternative technique for cervical epidural space visualization-A pilot study

Background

Neuraxial ultrasound (US), a newer modality, can be used for neuraxial imaging, helping in visualizing and aiding in epidural space catheterization. The aim of this study was to evaluate the efficacy of the US for cervical epidural access and to determine the failure rate and complication associated with this technique.

Methods

A prospective single-arm pilot study was conducted on 21 participants. The neuraxial US image quality assessment by Ultrasound Visibility Score (UVS), epidural space depth measurement by US and by conventional loss of resistance (LOR) technique, and post-procedure epidural catheter confirmation by real-time US were the study parameters. Any procedural complications or failure rate were recorded. The Kolmogorov-Smirnov test, paired-samples t-test, and Chi-square test were used for the statistical comparison.

Results

The pre-procedural UVS by the transverse interlaminar view (x/21) was 2.81 ± 1.94 and by the oblique paramedian sagittal view was 16.66 ± 2.39 with UVS being best in the paramedian oblique sagittal view (P- value < 0.05). The comparison of depth of the epidural space identified by USG and that by the LOR technique was statistically insignificant (P = 0.83). The average puncture attempts were 1.1 ± 0.3. Post-procedure US epidural catheter confirmation score (x/3) was 1.44 ± 0.44 with either epidural space expansion or microbubbles seen or both.

Conclusion

The pilot study has successfully demonstrated the implication of US for visualizing and aiding in epidural space catheterization. Also, the failure rate and procedural complications were drastically minimized with the help of US as compared to the traditional blind technique.

A Morphometric Study Analyzing the Anterior Epidural Space Volume Throughout Childhood

BACKGROUND

Following disc herniations, fragments migrate into the anterior epidural space within the lumbar spine. Although the volume of this area has been previously described in the adult population, the volume is relatively unknown within children.

OBJECTIVES

Investigate the relative volume in the lumbar anterior epidural space within the growing spine by using imaging studies.

STUDY DESIGN

Retrospective chart review.

SETTING

University Medical Center in Lubbock Texas. A teaching hospital affiliated with Texas Tech University Health Sciences Center.

METHODS

We conducted a retrospective review of the charts of pediatric patients seen at our institution from 2018 through 2020. Charts chosen for our investigation contained computed tomography imaging of the lumber spine, showing no deformities. Thirty patients were stratified equally among 3 age groups, 2-5 years old, 10-12 years old, and 16-18 years old. The anterior epidural space was measured in each patient 3 times using the previously reported method used by Teske et al (1). Results were compared with a combination of analysis of variance (ANOVA) and single tail paired t test.

RESULTS

There was a statistically significant difference in the anterior epidural space size among age groups at all levels of the lumbar spine. When comparing only 2 groups together, the younger age group had anterior epidural space sizes significantly smaller than the other age group for all levels of the lumbar spine. The 10-12 age group had a significantly smaller space in the anterior epidural space than the 16-18-year olds only at the level of L2, L4, and L5 (P = 0.048,0.039, and 0.031, respectively). Within the 16-18-year age group, the anterior epidural space was significantly different between L4 and L3 and L2 and L3 (P < 0.001 and P = 0.019, respectively).

LIMITATIONS

Our study is limited by its retrospective nature and the sample size of the patient groups. Furthermore, the use of computed tomography imaging and not making physical measurements limits our accuracy.

CONCLUSION

The volume of the anterior epidural space is smaller in the pediatric population than the adult population. The inability of herniated discs to fit within the epidural space in children and adolescents could potentially be the cause of the increased failure of conservative treatment for pediatric lumbar disc herniations.

Usage of augmented reality for interventional neuraxial procedures: A phantom-based study

BACKGROUND

Neuraxial access is necessary for an array of procedures in anaesthesia, interventional pain medicine and neurosurgery. The commonly used anatomical landmark technique is challenging and requires practical experience.

OBJECTIVE

We aimed to evaluate the technical feasibility of an augmented reality-guided approach for neuraxial access and tested the hypothesis that its use would improve success as the primary outcome. As secondary outcomes, we measured accuracy and the procedural duration compared with the classical landmark approach.

DESIGN

A randomised phantom-based study.

SETTING

The three-dimensional image of a thoracolumbar phantom spine model with the surrounding soft tissue was created with a neurosurgical planning workstation and ideal trajectories to the epidural space on the levels T10-L1 were planned using a paramedian approach. Both the three-dimensional holographic image of the spine and the trajectories were transferred to an augmented reality-headset. Four probands (two anaesthesiologists, one neuroradiologist and one stereotactic neurosurgeon) performed 20 attempts, 10 each of either conventional landmark or augmented reality-guided epidural punctures, where anatomical level, side and sequence of modality were all randomised.

OUTCOME MEASURES

Accuracy was assessed by measuring Euclidean distance and lateral deviation from the predefined target point. Success of epidural puncture on the first attempt was compared between the conventional and the augmented reality-guided approaches.

RESULTS

Success was achieved in 82.5% of the attempts using augmented reality technique, compared with 40% with the conventional approach [ P  = 0.0002, odds ratio (OR) for success: 7.07]. Euclidean distance (6.1 vs. 12 mm, P  < 0.0001) and lateral deviation (3.7 vs. 9.2 mm, P  < 0.0001) were significantly smaller using augmented reality. Augmented reality-guided puncture was significantly faster than with the conventional landmark approach (52.5 vs. 67.5 s, P  = 0.0015).

CONCLUSION

Augmented reality guidance significantly improved the accuracy and success in an experimental phantom model of epidural puncture. With further technical development, augmented reality guidance might prove helpful in anatomically challenging neuraxial procedures.

Ligamentum Flavum Rupture by Epidural Injection Using Ultrasound with SMI Method

The loss of resistance (LOR) method has been used exclusively to identify epidural space. It is difficult to find the epidural space without the risk of dural puncture. Various devices have been developed to improve the accuracy of the LOR method; however, no method has overcome the problems completely. Therefore, we devised a ligamentum flavum rupture method (LFRM) in which the needle tip is placed only on the ligamentum flavum during the epidural injection, and the injection pressure is used to rupture the ligamentum flavum and spread the drug into the epidural space. We confirmed the accuracy of this method using ultrasound with superb microvascular imaging (SMI) to visualize the epidural space. Here, we report two cases of 63-year-old and 90-year-old males. The 63-year-old patient presented with severe pain in his right buttock that extended to the posterior lower leg. The 90-year-old patient presented with intermittent claudication every 10 min. LFRM was performed, and SMI was used to confirm that the parenteral solution had spread into the epidural space. Our results indicate that LFRM can be used for interlaminar lumbar epidural steroid injections.

Color flow Doppler in spinal ultrasound: a novel technique for assessment of catheter position in labor epidurals

BACKGROUND

Ultrasound is commonly used to facilitate epidural catheter placement. However, data are lacking regarding its potential to confirm its position in the epidural space. Our aim was to visualize flow in the epidural space of patients receiving epidural analgesia for labor using color flow Doppler ultrasound.

METHODS

We conducted a prospective observational cohort study that included patients who had delivered vaginally under epidural analgesia. We used a 5-2 mHz curvilinear probe in a left and right paramedian longitudinal oblique view to visualize the anterior and posterior complex at the interspace of epidural catheter insertion, one and two interspaces above and below. At each window, the color flow Doppler function was used to visualize flow within the epidural space on injection of normal saline (1 mL). If no flow was visualized at any interspace, one assessment at the level of insertion was repeated with a 1 mL air/saline mixture. We studied a convenience sample size of 40 patients.

RESULTS

We visualized flow in the epidural space in all 40 patients. Flow was visualized on injection of 1 mL of saline in 37/40 patients (93%). In the remaining 3/40 patients (7%), flow was visualized with an air/saline mixture. Flow on injection of saline was visualized only at the interspace of insertion in 26/37 patients (70%), at the interspace of insertion and one interspace above in 10/37 (27%), or only at one interspace above in 1/37 (3%). Flow was visualized only on the left or on the right paramedian view in 19/37 patients (51%), despite a symmetrical sensory block in all patients.

CONCLUSION

Color flow Doppler ultrasound is a feasible and fast way to determine flow in the epidural space in the obstetric population. Its potential clinical uses are confirmation of the epidural catheter position after placement, as well as troubleshooting of unsatisfactory epidural analgesia. Interestingly, our results suggest that epidural catheters predominantly remain at the interspace of insertion.

TRIAL REGISTRATION NUMBER

NCT05126745.

Cervical Epidural Abscess: A Blind Spot for Postmortem Computed Tomography

ABSTRACT

Spinal epidural abscess is an uncommon condition, which may have serious complications, including neurological sequelae and death. Classical symptoms include spinal pain, fever, and neurological deficit; however, diagnosis is difficult and requires a high degree of clinical suspicion. Antemortem magnetic resonance imaging (MRI) scanning is the gold-standard diagnostic tool. Computed tomography (CT) is less sensitive and as such, postmortem CT may miss the diagnosis. We report a case of Staphylococcus aureus cervical epidural abscess presenting as neck pain and causing flaccid paralysis and subsequently death. Antemortem MRI showed a small epidural collection, spinal cord edema, and fluid in the adjacent cervical disc and facet joints; however, these findings could not be appreciated on postmortem CT. Postmortem examination, guided by the antemortem imaging, was able to confirm a cervical spinal epidural abscess; however, similar deaths may occur before medical presentation. This case demonstrates a limitation of postmortem imaging in diagnosing spinal epidural abscess and highlights that such cases may be missed.

Direct Visualization of Cervical Interlaminar Epidural Injections Using Sonography

In this case series, we describe a novel ultrasound (US)-guided cervical interlaminar epidural steroid injections (CILESIs) procedure that does not depend on the loss-of-resistance method for epidural space identification. A needle is introduced into three US-identified structures (triple bar sign), the interspinal ligament, ligamentum flavum, and dura mater. The injectants are monitored using superb microvascular imaging during injection. Here, we demonstrate the use of US-guided CILESIs in nine cases and propose the use of sonography, rather than conventional methods, for easier and safer cervical epidural injections. Sonography for direct visualization of cervical epidural injection may allow for outpatient injections.

Comparison of Increase in the Optic Nerve Sheath Diameter between Epidural Saline and Contrast Medium Injections

BACKGROUND

Normal saline or contrast medium is one of the widely used injection materials during fluoroscopic guided injections. Optic nerve sheath diameter (ONSD) measurement is a reliable and noninvasive method for intracranial pressure evaluation.

OBJECTIVES

The purpose of this study was to compare the increase in ONSD and cerebral oxygen saturation (rSO2) between normal saline and contrast medium when they were injected into the epidural space.

STUDY DESIGN

Prospective randomized trial.

SETTING

An interventional pain management clinic in South Korea.

METHODS

This study included 42 patients who were scheduled to receive thoracic epidural catheterization for postoperative pain control. Patients were randomly allocated to receive 5 mL normal saline or contrast medium following successful thoracic epidural entry. The ONSD was measured using transorbital sonography at baseline (T0), 10 min (T10), 20 min (T20), and 40 min (T40) after epidural normal saline or contrast medium injection.

RESULTS

Both groups demonstrated significant increases in ONSD from T10 to T40 when compared with the baseline. Although both groups showed a significant increase in ONSD compared with the baseline, group saline showed a higher increase in ONSD than group contrast. A significantly higher increase in ONSD in group saline than in group contrast was maintained from T10 to T40 (P = 0.015).

LIMITATIONS

We could not determine the returning point of the normalized ONSD value.

CONCLUSION

Thoracic epidural injection of 5 mL normal saline or contrast medium resulted in a significant increase of ONSD compared to baseline; however, the degree of ONSD increase was more attenuated in the contrast group than the saline group.

Posterior epidural migration of lumbar disc fragment: Case reports and literature review

INTRODUCTION

Posterior epidural migration of lumbar disc fragment (PEMLDF) is a very rare condition that may lead to a serious neurological deficit such as cauda equina syndrome. Magnetic resonance imaging (MRI) findings can often result in cases of PEMLDF being misdiagnosed as extradural masses of other origin or epidural hematomas. In this study, we reported four additional cases of PEMLDF and reviewed the relevant literature.

PATIENT CONCERNS

We present four patients with PEMLDF. The mean age of the patients was 53.5 years. Two patients suffered from cauda equine syndrome, and the other two patients complained of radiculopathy.

DIAGNOSIS

The MRI findings in each case showed masses with slightly high signal intensity in T2-weighted images, as well as heterogenous and peripheral rim enhancement after contrast enhancement. In some patients there was a tract-like enhancement extending from the outer aspect of the disc to the posterolateral epidural space. A definitive diagnosis was made intraoperatively.

INTERVENTIONS

We performed laminectomy and discectomy in all patients.

OUTCOMES

The PEMLDF patients with radiculopathy had no complaints of weakness or pain after surgery. Both patients with cauda equine syndrome showed a total recovery post-surgery.

CONCLUSIONS

Early diagnosis and treatment via laminectomy and discectomy is critical to achieving the best postoperative outcomes. Understanding the patient's history, recognizing the similar signal intensity of the mass and intervertebral disc on MRI scans, and looking for peripheral rim enhancement, are the keys to the correct diagnosis of PEMLDF.

The Correlation of Epidural Fibrosis with Epiduroscopic and Radiologic Imaging for Chronic Pain after Back Surgery

BACKGROUND

Chronic low back pain is observed frequently after lumbar spinal surgery. Epidural fibrosis has been implicated in the etiology of persistent pain after back surgery. The incidence of epidural fibrosis increases as the number and extent of spinal surgery increases. Epidural fibrosis can be detected by conventional radiologic methods [e.g., lumbosacral magnetic resonance imaging (MRI) with gadolinium], but these methods are insufficient to reveal the presence of epidural adhesions. Imaging of the epidural cavity using an epiduroscope is one of the best methods for visualizing the spinal cavity without damaging anatomic structures.

OBJECTIVES

To evaluate the correlation between the type and number of surgery and the degree of epidural fibrosis and to compare epidural fibrosis in epiduroscopic and MRI findings in patients with failed back surgery syndrome (FBSS).

STUDY DESIGN

A prospective trial.

SETTING

A university hospital.

METHODS

This study included 61 patients with persistent low back pain and/or radicular pain for at least 6 months, despite lumbar surgery and conservative treatment, and who accepted epiduroscopic imaging. All patients were evaluated in a physical examination using a visual analog scale (VAS) per the elapsed time after surgery. The patients were divided into 3 groups according to the number and type of surgeries. Epidural fibrosis was rated using MRI with gadolinium and epiduroscopy.

RESULTS

When the relationship between admission symptoms and epidural fibrosis was evaluated, MRI findings of fibrosis were found to be significantly higher in all patients with both lumbar and radicular pain symptoms at the confidence level of 95% (P = 0.001). The degree of fibrosis detected using epiduroscopy was grade 1 and 2 in almost all patients who presented with low back pain only, only radicular pain, or only distal paresthesia (P = 0.001). In the correlation analysis between the duration of the postoperative period (4.13 ± 2.97 years) and the degree of fibrosis detected using MRI and epiduroscopy, a statistically significant relationship was found at the confidence level of 95% (P < 0.05). As the number and extent of spinal surgeries increased, the incidence of MRI fibrosis increased, which is compatible with the literature (P = 0.001) There was a statistically significant relationship between the degree of fibrosis as detected using MRI and epiduroscopy at the confidence level of 95% (P < 0.05). Differently, we observed that 6 patients had grade 1 fibrosis as diagnosed using epiduroscopy, whereas none had fibrosis on MRI.

LIMITATIONS

We did not have a control group. Further studies are required to demonstrate the relevance of these 2 imaging techniques (epiduroscopy and MRI) in terms of detecting epidural fibrosis in patients with FBSS.  CONCLUSIONS: Epiduroscopic imaging seems to be more sensitive than MRI in detecting grade I epidural fibrosis in patients with FBSS. Thus, the possibility of low-grade epidural fibrosis as a source of pain after back surgery, should be kept in mind in normally reported MRIs. Treatment should be planned accordingly.

Fiber Optic Distributed Sensing Network for Shape Sensing-Assisted Epidural Needle Guidance

Epidural anesthesia is a pain management process that requires the insertion of a miniature needle through the epidural space located within lumbar vertebrae. The use of a guidance system for manual insertion can reduce failure rates and provide increased efficiency in the process. In this work, we present and experimentally assess a guidance system based on a network of fiber optic distributed sensors. The fibers are mounted externally to the needle, without blocking its inner channel, and through a strain-to-shape detection method reconstruct the silhouette of the epidural device in real time (1 s). We experimentally assessed the shape sensing methods over 25 experiments performed in a phantom, and we observed that the sensing system correctly identified bending patterns typical in epidural insertions, characterized by the different stiffness of the tissues. By studying metrics related to the curvatures and their temporal changes, we provide identifiers that can potentially serve for the (in)correct identification of the epidural space, and support the operator through the insertion process by recognizing the bending patterns.

Dural sac shrinkage signs on magnetic resonance imaging at the thoracic level in spontaneous intracranial hypotension-its clinical significance

BACKGROUND

Spontaneous intracranial hypotension (SIH) is secondary to a cerebrospinal fluid leak at the spinal level without obvious causative events. Several signs on brain and cervical spine magnetic resonance (MR) imaging (MRI) have been associated with SIH but can be equivocal or negative. This retrospective study sought to identify characteristic SIH signs on thoracic spinal MRI.

METHODS

Cranial and spinal MR images of 27 consecutive patients with classic SIH symptoms, who eventually received epidural autologous blood patches (EBPs), were analyzed.

RESULTS

The most prevalent findings on T2-weighted MRI at the thoracic level were anterior shift of the spinal cord (96.3%) and dorsal dura mater (81.5%), probably caused by dural sac shrinkage. These dural sac shrinkage signs (DSSS) were frequently accompanied by cerebrospinal fluid collection in the posterior epidural space (77.8%) and a prominent epidural venous plexus (77.8%). These findings disappeared in all six patients who underwent post-EBP spinal MRI. Dural enhancement and brain sagging were minimum or absent on the cranial MR images of seven patients, although DSSS were obvious in these seven patients. For 23 patients with SIH and 28 healthy volunteers, a diagnostic test using thoracic MRI was performed by 13 experts to validate the usefulness of DSSS. The median sensitivity, specificity, positive-predictive value, negative-predictive value, and accuracy of the DSSS were high (range, 0.913-0.931).

CONCLUSIONS

Detection of DSSS on thoracic MRI facilitates an SIH diagnosis without the use of invasive imaging modalities. The DSSS were positive even in patients in whom classic cranial MRI signs for SIH were equivocal or minimal.

Isolated primary spinal epidural hydatid cyst in a child with progressive paraparesis

BACKGROUND

Primary spinal hydatid cyst is a rare but serious condition which occurs in about 1% of patients with hydatid disease. This disease may result in severe spinal cord compression presenting with various neurological deficits.

CASE REPORT

A 3-year-old boy was referred to our center with progressive weakness of lower limbs, frequency, and urinary incontinence. His parents did not report back pain during child's illness. Lumbar magnetic resonance imaging (MRI) revealed an extradural well-defined thin-walled cystic lesion at L4 to S3 vertebral levels without enhancement. The cyst had compressed the thecal sac associated with bone scalloping of vertebral bodies and posterior elements. Osteoplastic laminectomy of L4-L5 and laminectomy of S1-S3 was done. Intraoperative and histopathological findings indicated an epidural hydatid cyst.

CONCLUSION

Although spinal hydatid cysts are rare but might be considered in the differential diagnosis of any patient with signs and symptoms of spinal cord compression. The pathophysiology, clinical manifestations, epidemiology, diagnosis, and surgical treatment of extradural hydatid cyst are discussed.

[Minimally invasive treatment of cervical1-2 epidural neurilemmoma]

OBJECTIVE

To explore the minimally invasive surgical method for cervical1-2 epidural neurilemmoma.

METHODS

The clinical features, imaging characteristics and surgical methods of 63 cases of cervical1-2 epidural neurilemmoma from July 2010 to December 2018 were reviewed and analyzed. Pain and numbness in occipitocervical region were the common clinical symptoms. There were 58 cases with pain, 30 cases with numbness, 3 cases with limb weakness and 2 cases with asymptomatic mass. Magnetic resonance imaging (MRI) showed that the tumors located in the cervical1-2 epidural space with diameter of 1-3 cm. The equal or slightly lower T1 and equal or slightly higher T2 signals were found on MRI. The tumors had obvious enhancement. Individualized laminotomy was performed according to the location and size of the tumors, and axis spinous processes were preserved as far as possible. Resection of tumor was performed strictly within the capsule.

RESULTS

Total and subtotal resection of tumor were achieved in 60 and 3 cases respectively, and no vertebral artery injury was found. The operation time ranged from 60 to 180 minutes, with an average of 92.83 minutes. The hospitalization time ranged from 3 to 9 days, with an average of 5.97 days. All tumors were confirmed as neurilemmoma by pathology. There was no postoperative infection or cerebrospinal fluid leakage. There was no new-onset dysfunction except 9 cases of numbness in the nerve innervation area. The period of follow-up ranged from 6 months to 8 years (median: 3 years). All the new-onset dysfunction recovered completely. Pain disappeared in all of the 58 patients with pain. Numbness recovered completely in 27 patients while slight numbness remained in another 3 patients. Three patients with muscle weakness recovered completely. The spinal function of all the patients restored to McCormick grade Ⅰ. No recurrence was found on MRI. No cervical spine instability or deformity was found on X-rays.

CONCLUSION

It is feasible to resect cervical1-2 epidural neurilemmoma by full use of the anatomical space between atlas and axis and individual laminotomy. It is helpful to prevent cervical instability or deformity by minimizing the destruction of cervical2 bone and preserving normal muscle attachment to cervical2 spinous process. Strict intracapsular resection can effectively prevent vertebral artery injury.

Comparison of Thoracic Epidural Access with Lateral Decubitus and Shoulder Rotation Positions for Repeat Thoracic Epidural Blockade

BACKGROUND

Shoulder rotation has been shown to increase the acoustic window of ultrasound for thoracic epidural access. However, this effect of shoulder rotation has not yet been confirmed in clinical practice.

OBJECTIVE

This study aimed to evaluate the effects of shoulder rotation on the thoracic epidural blockade in patients with acute or chronic pain in the thoracic region.

STUDY DESIGN

Prospective crossover trial.

SETTING

Pain clinic of our university in the Republic of Korea.

METHODS

Forty patients aged 20 - 80 years with acute or chronic pain in the thoracic region who were scheduled to undergo thoracic epidural blockade more than twice.

INTERVENTIONS

The patients underwent repeated fluoroscopy-guided thoracic epidural blockade via the paramedian approach in the lateral decubitus position either with or without shoulder rotation.The primary outcome measure was the attempt time to the confirmed spread of contrast. The number of attempts, total procedure time, vertical interpedicular distance, contrast spreading length, and complications were compared between the 2 positions.

RESULTS

The median attempt times in the lateral decubitus and shoulder rotation positions were 138.8 and 132.5 seconds, respectively, and this difference was significant (P = 0.004). Compared with the lateral decubitus position, the shoulder rotation position was also associated with a significantly lower number of attempts (P = 0.03), shorter total procedure time (P < 0.001), and greater vertical interpedicular and contrast spreading distances (P < 0.001 and P = 0.02, respectively).

LIMITATIONS

The operator in this study was not blinded to the patient groups. Other researchers observed the operator's procedure and evaluated and recorded the data in an attempt to overcome this bias. However, it was difficult to completely avoid the bias. Second, epidural blockade was performed at various levels (T3-11), and the anatomical features vary among thoracic spine levels.

CONCLUSIONS

The study findings demonstrate the clinical benefits of the shoulder rotation position versus the lateral decubitus position in terms of successful epidural access during thoracic epidural blockade using the paramedian approach.

Microsurgical treatment for spinal epidural angiolipomas

Spinal epidural angiolipomas are rare lesions composed of mature lipomatous and angiomatous elements. In this paper, the authors review a surgical series of ten patients with epidural angiolipomas. All patients had performed preoperative and postoperative magnetic resonance imaging. The diagnosis of angiolipoma was based on pathology. All the follow-up data were obtained during office visits. There were 5 males and 5 females with a mean age of 53.6 years. One tumor was located in the cervicothoracic, six in the thoracic, and three in the lumbar spine. The most common symptom was progressive motor deficit. Gross total resection of the tumor was achieved in nine cases, and subtotal resection was obtained in one case. No recurrence or regrowth of the residual tumor was observed during a follow-up period of 50.8 months. At the last follow-up, 90% of patients experienced improvement in the neurological function. Epidural angiolipomas are benign but clinically progressive lesions. Early surgery should be performed to prevent irreversible neurological deficits. Postoperative radiotherapy is not recommended. The risk of long-term recurrence/regrowth of the lesions is low, and a good clinical outcome after total or subtotal removal can be expected.

Spinal Epidural Fistulas-A Separate Entity to Dural Fistulas with Different Angioarchitecture and Treatment Approach

OBJECTIVE

Spinal epidural arteriovenous fistulas (SEAVFs) are the rarest variety of spinal vascular malformation and are often misdiagnosed as type 1 spinal dural fistula. This retrospective study highlights the salient anatomic differentiating points of these entities and also highlights the importance of a planned endovascular treatment approach using different routes of access. Efficacy of the endovascular treatment at 3 months follow-up was also studied.

METHODS

We retrospectively reviewed 11 treated patients with SEAVF. Existence of epidural arteriovenous fistula in all these patients was confirmed by spinal angiography. The Aminoff-Logue Scale score was assigned both before and after the procedure. The statistical results were expressed as percentages, and the preprocedure scale was compared with the postprocedure scale at 3 months by using a nonparametric Wilcoxon signed-rank test.

RESULTS

The patients ranged in age from 7 to 53 years, with male predominance. Paraparesis was the commonest symptom, and 1 patient had congestive cardiac failure caused by a large fistula. Location was mostly dorsolumbar with intradural venous reflux into the perimedullary venous system (Castilla type A) noted in 3/11(27%) patients, and the remaining 73% patients had Castilla type B1 with an enlarged epidural venous sac. Therapeutic embolization was performed from arterial, venous, or combined routes. The 3-month postprocedure clinical assessment showed statistically significant (P < 0.004) improvement in the Aminoff-Logue Scale score.

CONCLUSIONS

The differentiating points between SEAVF compared with type 1 spinal dural fistula are emphasized. The study also highlights the importance of a good angiographic assessment to best access the fistula by arterial, venous, percutaneous, or combined routes. Endovascular treatment resulted in statistically significant clinical improvement at 3 months follow-up.

[Epidural lipomatosis : management proposal]

Epidural lipomatosis is a rare condition characterized by excessive accumulation of normal fat in the epidural space. This paper presents the results of a retrospective study of the charts of 20 patients. The 20 patients - 17 men and 3 women - were on average 64 years old. They suffered from radiculopathy and/or neurogenic claudication. Lipomatosis was idiopathic in 6 patients and secondary in 14 patients. Lipomatosis was MRI grade 2 in 30 % of cases and grade 3 in 70 % of cases. The patients have all been improved thanks to decompressive surgery by laminectomy and resection of epidural fat. According to our experience and to the literature, surgical decompression is an effective and safe procedure for patients with symptomatic lumbar epidural lipomatosis in case of failure of conservative treatment or in case of neurological deficits. We present a decision tree that can help in the management of this disease.

Evaluation of Contralateral Oblique and Lateral Views for Mid-Thoracic Epidural Access: A Prospective Observational Study

BACKGROUND

The mid-thoracic region has been known to be the most difficult area when accessing epidural space despite using fluoroscopy. Contralateral oblique (CLO) view has been considered for use; however, it has not been evaluated in the mid-thoracic region.

OBJECTIVE

To evaluate the CLO view for mid-thoracic epidural access (TEA).

STUDY DESIGN

A prospective observational study.

SETTING

The study took place at a single pain clinic within a tertiary medical center in Seoul, Republic of Korea.

METHODS

A total of 30 patients participated in this study. After securing the mid-thoracic (T4-8) epidural space, fluoroscopic images were obtained. The needle tip location relative to the ventral interlaminar line (VILL), and the needle tip and laminar visualization were measured and analyzed on the CLO views at 40, 50, 60 degrees, and measured angle, and the lateral view.

RESULTS

The needle tip was clearly visualized in all CLO views, compared with the lateral view (100% vs. 36.7%, P < 0.001). The visualization of the laminar margin and the needle tip location on (or just anterior to) VILL using the CLO measured angle were significantly clearer compared with those in the CLO view at 40 and 50 degrees and the lateral view (laminar margin: 40°, 56.7% vs. 3.3%, P < 0.001; 50°, 56.7% vs. 26.7%, P = 0.012; 90°, 56.7% vs. 26.7%, P = 0.035; needle tip location: 40°, 96.7% vs. 26.7%, P < 0.001; 50°, 96.7% vs. 63.3%, P = 0.002; 90°, 96.7% vs. 66.7%, P = 0.012). There was no difference in these values between the CLO view at 60 degrees and CLO measured angle.

LIMITATIONS

Subjective and ambiguous criteria of evaluation may induce bias despite final measured values based on the consensus of an independent investigator.

CONCLUSION

A CLO view at 60 degrees and CLO measured angle view can provide clearer visualization and more consistent needle tip location than the lateral and other CLO angle views for mid-TEA. A CLO view at 60 degrees and CLO measured angle views could be used to identify the needle location and achieve success in mid-TEA.

Clinical Implications of the Epidural Fat Thickness in the Management of Lumbar Spinal Stenosis

OBJECTIVE

Lumbar epidural lipomatosis is a rare condition defined as the excessive accumulation of epidural fat (EF). We herein investigated the indicators of the posterior compression factors, EF and yellow ligament, to identify the clinical features of lumbar epidural lipomatosis.

METHODS

Five hundred consecutive patients who underwent posterior lumbar decompression surgery for lumbar spinal stenosis (LSS) were retrospectively reviewed. The EF/SC-L index (the ratio of the anteroposterior length of the EF to that of the spinal canal [SC]) was evaluated at the spinal level that exhibited maximum dural tube compression. The participants were divided into 3 groups: grade I, EF/SC-L index ≤50%; grade II, EF/SC-L index 51%-74%; grade III, EF/SC-L index ≥75%. EF/SC-A (the ratio of the cross-sectional area of EF to that of SC) and YL/SC-A (the ratio of the cross-sectional area of yellow ligament [YL] to that of SC) were calculated. The clinical outcomes were assessed according to the Japan Orthopaedic Association scale for lumbar disease.

RESULTS

EF/SC-L exhibited a significantly positive correlation with EF/SC-A (r = 0.82, P < 0.001), and a negative correlation with YL/SC-A (r = -0.71, P < 0.001). The Japan Orthopaedic Association score recovery rate was 56.7 ± 22.6 in the case-matched control group, 34.5 ± 31.2 in the grade II group (P < 0.001), and 39.6 ± 24.9 in the grade III group (P = 0.032).

CONCLUSIONS

The EF/SC-L index is a simple and reliable indicator to quantitatively evaluate posterior compression in patients with LSS. As the accumulation of EF is associated with worse operative outcomes, the EF/SC-L index should be considered when planning lumbar decompression surgery for patients with LSS.

Automatic Midline Identification in Transverse 2-D Ultrasound Images of the Spine

Effective epidural needle placement and injection involves accurate identification of the midline of the spine. Ultrasound, as a safe pre-procedural imaging modality, is suitable for epidural guidance because it offers adequate visibility of the vertebral anatomy. However, image interpretation remains a key challenge, especially for novices. A deep neural network is proposed to automatically classify the transverse ultrasound images of the vertebrae and identify the midline. To distinguish midline images from off-center frames, the proposed network detects the left-right symmetric anatomic landmarks. To assess the feasibility of the proposed method for midline detection, a data set of ultrasound images was collected from 20 volunteers, whose body mass indices were less than 30. The data were split into two segments, for training and test. The performance of the proposed method was further evaluated using fourfold cross validation. Moreover, it was compared against a state-of-the-art deep neural network. Compared with the gold standard provided by an expert sonographer, the proposed trained network correctly classified 88% of the transverse planes from unseen test patients. This capability supports the first step of guiding the placement of an epidural needle.

Spinal Epidural Lipomatosis with Osteoporotic Vertebral Fractures Presenting as Acute Thoracic Myelopathy in a 33-Year-Old Man with Cushing Disease

BACKGROUND

Steroid-related spinal epidural lipomatosis (SEL) is a well-known condition most commonly encountered in patients taking chronic steroid medications. Endogenous Cushing syndrome is a rare cause of SEL. The authors report an unusual presentation of acute thoracic myelopathy due to SEL with osteoporotic vertebral compression fractures in a patient with Cushing disease.

CASE DESCRIPTION

A 33-year-old man presented with thoracic myelopathy due to SEL and multiple vertebral compression fractures. He had Cushingoid clinical features, and investigations revealed a pituitary microadenoma as the cause of hypercortisolism. The diagnosis was missed on multiple occasions before the onset of paraparesis. The patient was treated with urgent thoracic laminoplasty followed by transsphenoidal surgery on the same day. Although normalization of the serum cortisol levels was delayed by 6 months, he had a complete neurologic recovery and remains symptom free at 2 years follow-up.

CONCLUSIONS

This is a rare presentation of Cushing disease and has been reported only twice before in the 1990s. This case highlights the need to keep a high degree of suspicion for development of thoracic myelopathy in a patient with Cushing syndrome who develops thoracic compression fractures associated with SEL. Early recognition of this clinical association and addressing the primary endocrine problem urgently could have prevented spinal cord involvement and the subsequent spine surgery. This scenario is also documented in previous published case reports of this association where the diagnosis of Cushing syndrome has been revealed retrospectively after the development of neurologic symptoms.

Nonfusion Muscle-Sparing Technique to Treat Long-Segment Thoracolumbar Extradural Arachnoid Cyst in a Child: A Case Report and Review of the Literature

BACKGROUND

Spinal extradural arachnoid cyst is an uncommon cause of spinal cord compression. It results from a small dural defect that leads to cerebrospinal fluid (CSF) accumulation in the cyst and subarachnoid space, and the cyst can compress the spinal cord and nerve roots. Surgery is the treatment of choice in symptomatic patients, and most cases have an immediately satisfying outcome after surgery.

CASE DESCRIPTION

A 10-year-old Thai boy presented with progressive weakness in both legs. Magnetic resonance imaging (MRI) demonstrated a giant cystic lesion 23 cm in length from T1-L2 level. To our knowledge, this is the longest arachnoid cyst that has been reported in children. The operation included unilateral paraspinal muscle dissection with spinous process translation techniques, T1-L4 laminectomy, total cyst excision, and dural defect repair at the T4 level. The symptoms were fully resolved within 2 months after surgery. However, thoracic kyphosis was slightly increased, but the patient still has a normal sagittal profile.

CONCLUSIONS

Spinal arachnoid cyst is rare, especially in children. Early diagnosis and treatment are essential for improving the chance of full recovery, and for avoiding complication and irreparable defect. Total cyst removal with dural repair remains the best treatment alternative; however, potential complications, especially spinal malalignment after extensive laminectomy, must be considered. Postoperative MRI showed normal CSF flow and no spinal cord compression. The muscle-sparing technique with multiple-level laminectomy without spinal fusion that we used in this case provided a satisfying outcome.

Contrast Medium Volume Needed to Reach Anterior Epidural Space via the Kambin Triangle or Subpedicular Approach for Transforaminal Epidural Injection

BACKGROUND

Transforaminal (TF) lumbar injection is a commonly used minimally invasive intervention for management of chronic low back pain. TF injection can be performed using various approaches to inject the drug to the anterior epidural space (AES).

OBJECTIVES

To identify the volumes of contrast medium needed to reach the AES and other landmarks in the Kambin triangle (KB) and subpedicular (SP) approach of TF injection in patients with lumbosacral radicular pain.

STUDY DESIGN

Randomized controlled trial.

SETTING

Pain clinic and operating room of a tertiary care hospital.

METHODS

Seventy-five eligible patients were randomized to receive TF epidural injection either by SP (SP group; n = 38) or the KB (KB group; n = 37) approach under fluoroscopic guidance. After confirming the appropriate needle position, contrast medium was injected at 0.5 mL increments up to 2 mL under intermittent fluoroscopy. Contrast medium volumes needed to reach specific landmarks, that is, AES, medial to superior pedicle, medial to inferior pedicle, medial aspect of both the superior, and neural spread, were recorded. Following this, 4 mL of the drug (0.5% lidocaine 1 mL + methylprednisolone 80 mg + 1 mL normal saline solution) was injected. Patients were evaluated for Visual Analog Scale (VAS) and modified Oswestry Disability Questionnaire (MODQ) scores after epidural injections at 2 weeks, 1 month, and 2 months.

RESULTS

Average volume of contrast medium needed to reach AES was 1.10 ± 0.46 mL in the KB approach and 1.10 ± 0.38 mL in the SP approach. Contrast medium volume needed to reach other landmarks showed comparable results in both groups. AES was seen in 27.02% (10/37) patients in the KB group and 23.6% (9/38) patients in the SP group with 0.5 mL of contrast medium. This increased to 56.76% (21/37) and 77.7% (28/38) with 1 mL of contrast medium (P = 0.03, chi-square test). No anterior spread was seen even after 2 mL of contrast medium in 4 patients in the KB group and 2 patients in the SP group. Neural spread was seen in 100% of patients in the KB group after 0.5 mL of contrast medium, but in 34 (89.4%) patients in the SP group (P = 0.03, chi-square test). We did not note any contralateral spread. Short-term effectiveness in pain relief in terms of VAS for back pain and functional improvement in terms of MODQ score over time showed similar results in both groups. Intravascular needle puncture and needle paresthesia was comparable in both groups.

LIMITATIONS

Small follow-up duration is one the limitations of this study. Future studies will be needed to assess any long-term differences in outcome between approach methods. Also, use of intermittent fluoroscopy might have limited detection of intravascular injections of the contrast medium in comparison to the continuous fluoroscopy.

CONCLUSIONS

To conclude, our study revealed that average volume of contrast medium needed to reach AES and other landmarks were comparable with both approaches of TF injection.

KEY WORDS

Transforaminal injection, subpedicular approach, Kambin triangle approach, contrast medium spread, anterior epidural spread.

Comparison of Epidural Pressure Decrease Pattern According to Different Lumbar Epidural Approaches

BACKGROUND

During lumbar epidural injection (LEI) using a midline approach, we might encounter failure of identifying the epidural space owing to an equivocal or absent loss of resistance (LOR) sensation. The reason for such absence of LOR sensation has been suggested as paucity of midline ligamentum flavum, paravertebral muscle, and cyst in the interspinous ligament of the lumbar spine. Despite its low specificity, LOR is the most commonly used method to identify the epidural space.

OBJECTIVES

The purpose of this study was to analyze lumbar epidural pressure decrease patterns and identify factors contributing to this pressure decrease.

STUDY DESIGN

Prospective randomized trial.

SETTING

An interventional pain management practice in South Korea.

METHODS

This prospective study included 104 patients receiving LEI due to lumbar radiculopathy. A midline or paramedian approach of LEI was determined with randomization. Among various factors, gender, age, body mass index (BMI), and diagnosis were analyzed using a subgroup that included 60 cases of only a paramedian approach.

RESULTS

Grades I, II (abrupt decrease), and III (gradual decrease) were found as patterns of epidural pressure decrease. Abrupt pressure decrease was more frequently observed in the paramedian group (P < 0.001). Age, gender, BMI, and diagnosis did not show any significant difference in frequencies between abrupt and gradual pressure decrease.

LIMITATIONS

We could not match LOR sensation with epidural pressure decrease shown in the monitor.

CONCLUSIONS

This study demonstrates that abrupt pressure decrease occurs more frequently with the paramedian approach. However, age, gender, BMI, or diagnosis did not affect the incidence of epidural pressure decrease.

KEY WORDS

Epidural, paramedian, midline, pressure decrease.

Abdominal girth has a strong correlation with actual and ultrasound estimated epidural depth

Background/aim

This study aimed to assess the correlations of actual epidural depth (ND) and ultrasound estimated epidural depth in the paramedian sagittal oblique plane (ED/PSO) and transverse median plane (ED/TM) with the abdominal girth (AG), body mass index (BMI), and weight of patients.

Materials and methods

One hundred and thirty patients of either sex scheduled for unilateral inguinal hernia repair were enrolled. ED/PSO and ED/TM were assessed with a 2–5 MHz curved array probe at the L3–4 intervertebral space. The epidural needle was marked with a sterile marker upon locating the epidural space. The ND was assessed by measuring the distance from the sterile marker to the tip of the epidural needle with a linear scale. Anthropometric measures of the patients were recorded.

Results

ED/PSO was 49.6 ± 7.9 mm, ED/TM was 49.5 ± 7.9 mm, and ND was 50.0 ± 8.0 mm. AG was 99.8 ± 12.9 cm. The Pearson correlation coefficient between ND and ED/PSO was 0.997 and with ED/TM was 0.996 (P < 0.001 for both). Pearson correlation coefficients for ND with AG, BMI, and weight were 0.757, 0.547, and 0.638, respectively (P < 0.001 for all).

Conclusion

AG, weight, and BMI have strong correlations with ND.

Cross-sectional CT Assessment of the Extent of Injectate Spread at CT Fluoroscopy-guided Cervical Epidural Interlaminar Steroid Injections

Background Previous studies analyzed contrast agent spread during cervical interlaminar epidural steroid injections (CILESIs) by using planar fluoroscopy and reported wide variance of the rate of spread to the ventral epidural space (VES). Cross-sectional CT allows for direct viewing of contrast agent in the VES, providing improved spread assessment and thereby informing needle placement decisions when targeting pain generators. Purpose To determine the extent of injectate spread at CT fluoroscopy-guided CILESI, with particular attention to the VES and bilateral neuroforamina, by using cross-sectional CT. Materials and Methods This study reviewed 83 consecutive CT fluoroscopy-guided CILESIs at which a postprocedural cervical spine CT was performed (June 2016 to December 2017). All procedures used the same injectate (2 mL corticosteroid, 3 mL contrast agent). Postprocedural CT scans were reviewed for the presence of contrast within the VES, dorsal epidural space, ipsilateral neuroforamen, and contralateral neuroforamen in every cervical interlaminar level. Descriptive data are presented as frequencies or means. McNemar tests or hierarchical logistic models were used to assess associations between covariates and contrast agent spread to particular locations. Results The study cohort included 73 individual patients (59% women; 43 of 73) (mean patient age, 57.6 years ± 11.5 [standard deviation]). Mean number of levels of cranial spread were 0.6 level for VES, 1.9 levels for contralateral neuroforamen, 2.1 levels for ipsilateral neuroforamen, and 3 levels for dorsal epidural space. No VES spread in any level was found with 35% (29 of 83) of injections. VES spread was more likely to occur in the level of needle placement (43%; 36 of 83) than in other interlaminar levels (19.5%; 97 of 498; P < .001). Spread was more likely to occur in the neuroforamen ipsilateral to the needle approach compared with contralateral (P < .001). Conclusion Cervical interlaminar epidural steroid injections have injectate spreads with a mean of less than one level cranially in the ventral epidural space (VES) and approximately two levels in the neuroforamen. VES spread occurs more frequently at the level of needle placement and within the ipsilateral neuroforamen. © RSNA, 2019.

Selective Epidurography for the Assessment of Epidural Catheter Placement After Esophagectomy

BACKGROUND

Adequate pain control immediately after esophagostomy is critical to patient recovery and may be compromised by uncertainty regarding correct epidural catheter placement. The aim of the current study was to determine the role of performing an epidurogram in selective patients to assess epidural placement after esophagectomy.

METHODS

Patients undergoing esophagectomy in a high-volume center were retrospectively reviewed to identify those in whom an epidurogram was performed less than 24 hours after surgery. Since 2012 epidurograms have been selectively performed in patients and have demonstrated features concerning for incorrect epidural catheter placement, including difficult/complicated insertion, negative sensory test, nonreassuring intraoperative hemodyamic response, and inadequate postoperative pain control.

RESULTS

Fifty-two of 192 patients (27%; 43 men; age 65 ± 11 years) who underwent esophagostomy since 2012 had an epidurogram. Epidurograms were not associated with any adverse events. In 21 patients (40%) epidurogram findings led to a direct change in patient management, prompting either removal/replacement of an incorrectly sited catheter (n = 9), partial withdrawal of a catheter associated with unilateral contrast distribution (n = 2), or by endorsing a clinical decision to modify the analgesic regimen in a patient with a correctly sited epidural catheter (n = 10). Identifying and rescuing incorrect epidural catheter placement was not associated with longer intensive care unit/hospital stay or postoperative morbidity (p > 0.05) CONCLUSIONS: We reviewed selective epidurogram use in esophagectomy patients to determine its role in "rescuing" inadequate pain control through expediting clinical decision-making. Findings confirm that in selected patients epidurography is feasible and has the potential to directly contribute to patient care.

Radiographic and clinical outcomes of huge lumbar disc herniations treated by transforaminal endoscopic discectomy

OBJECTIVES

Large Central disc herniations (occupying more than 50% of canal area) are notorious as they are generally associated with worse outcomes and are technically difficult to manage. Transforaminal endoscopy (TELD) has evolved to become an interesting alternative for lumbar disc herniations. The aim of the paper is to review our technique of transforaminal endoscopy in large central disc herniations and describe the clinical and radiographic results. We also describe an innovative technique of intraoperative epidurography to assess the adequacy of decompression in some cases with severe canal compromise.

PATIENTS AND METHODS

We performed a retrospective analysis of all the patients undergoing TELD from December 2012 to October 2018 for huge central lumbar disc herniations. The procedure was done under local anaesthesia and required a more horizontal approach angle, undercutting of superior articular process and posterior annular release to reach the herniated fragment in the epidural space. In severe cases, a radiopaque dye was introduced via trans-sacral catheter to check the adequacy of decompression. The disc height, lumbar lordosis, segmental lordotic angle on standing radiographs and Canal cross sectional area(CSA) on MRI were evaluated preoperatively and compared with postoperative images at the end of 1 year/final follow-up. The Visual analogue scale(VAS) for Back and Leg pain and Oswestry disability index (ODI), MacNab criteria, return to daily activities, return to work, patient satisfaction rate and recommendation to others were the clinical outcomes evaluated. The percentage of patients achieving the Minimal clinically important difference (MCID) of 3 points for VAS and 12 points for ODI was calculated.

RESULTS

A total of 18 patients, with an average age of 35.1years (range 20-61), were operated. The mean VAS back improved from 5.7(±1.77) to 1(±0.77) and VAS leg improved from 7.3(±1.37) to 1.1(±1.09). The ODI improved from 49.88(±11.42) to 13.88(±7.28) at final follow-up. According to MacNab criteria, 17 patients had excellent and 1 had good outcome at final follow-up. The patient satisfaction rate was 90.5%, with 94% patient recommendation rate. All the patients returned to daily activities and work/modified work within a median of 5 weeks. There was 1 patient who required conversion to open surgery due to incidental dural tear, 1 patient who had a remnant disc required a revision tubular discectomy and 1 patient who had recurrence at 6 weeks and again at 2 years which was treated by repeat TELD. Five patients had impending cauda equina. All the patients achieved the MCID for VAS and ODI within a median period of 6 weeks and 3 months, respectively. The recovery rate was 90.1%. Five patients had grade 4 weakness of great toe/ankle dorsiflexion, one also had ankle flexion weakness preoperatively which improved after surgery. The CSA improved from a preoperative mean of 62.26(±30.3)mm² to 122.16(±56.5)mm² postoperatively. The CSA improved to 141.05(±63.86)mm² at 1 year followup. The average disc height which was 9.71 mm(±2.4) was maintained at follow-up of one year which was 9.21 mm(±2.4). The lumbar lordosis and segmental lordotic angle changed from 27.08°(±15.9) and 2.82°(±5.7) to 35.8°(±8.56) and 4.85°(±4.39) respectively.

CONCLUSION

TELD may be considered as an alternative to microdiscectomy or fusion procedures for huge central disc herniations with favourable outcomes. However, sufficient expertise with the procedure is necessary. Intraoperative decompression may be confirmed with intraoperative epidurography. The patient acceptability of the procedure is good and causes minimal disruption of the normal anatomy.

Fluoroscopic evaluation of the influence of needle gauge on epidural spread in caudal block

Caudal block has limited injectate distribution to the desired lumbar level due to the relatively long distance from the injection site and reduction in the volume of injectate due to leakage into the sacral foramen. The objective of this study was to investigate the influence of needle gauge on fluoroscopic epidural spread and to assess the correlation between the spread level and analgesic efficacy in patients undergoing caudal block. We retrospectively analyzed data from 80 patients who received caudal block for lower back and radicular pain. We categorized patients based on the epidural needle gauge used into group A (23 gauge), group B (20 gauge), and group C (17 gauge). Fluoroscopic image of the final level of contrast injected through the caudal needle and pain scores before the block and 30 minutes after the block recorded using a numerical rating scale, were evaluated. Of the 80 patients assessed for eligibility, 7 were excluded. Thus, a total of 73 patients were finally analyzed. Age, sex, body mass index, diagnosis, lesion level, lesion severity, and duration of pain did not differ among the 3 groups. All patients showed cephalic spread of contrast. Contrast spread beyond L5 was seen in 26.9% of patients in group A, 41.7% in group B, 39.1% in group C, and 35.6% overall; there was no significant difference among the groups (P = .517). Analgesic efficacy was not significantly different among the groups (P = .336). The needle gauge did not influence the level of epidural spread or analgesic efficacy in caudal block.

The Differential Flow of Epidural Local Anaesthetic via Needle or Catheter: A Prospective Randomized Double-blind Study

The extent of epidural anaesthesia and pattern of spread of contrast medium, using different injection techniques, has not been well documented. Therefore, in this prospective, randomized, double-blind study, the extent of anaesthesia and pattern of spread of contrast medium following an epidural bolus injection, via either a Tuohy needle or an epidural catheter, were compared.

The study had two parts. In the first, 59 of 79 patients scheduled for a lower extremity operation under epidural anaesthesia were randomly allocated to one of the two groups. Anaesthesia was achieved with an epidural injection of 10 to 15 ml (including a 3 ml test dose) of 0.75% ropivacaine and fentanyl 25 μg via either a Tuohy needle (Group N, n=31) or a catheter (Group C, n=28). The level of sensory anaesthesia was recorded. In the second part, the remaining 20 patients were randomized to initially receive 5 ml of contrast medium via either a Tuohy needle (Group NE, n=10) or a catheter (Group CE, n=10). The extent of spread was recorded radiologically.

Unilateral or missed blocks and additional dose requirement were absent in Groups N and C. No differences were found in the extent of sensory anaesthesia or the spread of contrast medium. Twenty per cent of catheter tips lay outside the lateral margins of the vertebral bodies.

We found that an epidural bolus injection, via either a Tuohy needle or a catheter, made no difference in regard to spread of local anaesthetic or contrast medium in the epidural space.

Comparison of Patient Position and Midline Lumbar Neuraxial Access Via Statistical Model Registration to Ultrasound

Patient positioning and needle puncture site are important for lumbar neuraxial anesthesia. We sought to identify optimal patient positioning and puncture sites with a novel ultrasound registration. We registered a statistical model to volumetric ultrasound data acquired from volunteers (n = 10) in three positions: (i) prone; (ii) seated with thoracic and lumbar flexion; and (iii) seated as in position ii, with a 10° dorsal tilt. We determined injection target size and penetration success by simulating lumbar injections on validated registered models. Injection window and target area sizes in seated positions were significantly larger than those in prone positions by 65% in L2-3 and 130% in L3-4; a 10° tilt had no significant effect on target sizes between seated positions. In agreement with computed tomography studies, simulated L2-3 and L3-4 injections had the highest success at the 50% and 75% midline puncture sites, respectively, measured from superior to inferior spinous process. We conclude that our registration to ultrasound technique is a potential tool for tolerable determination of puncture site success in vivo.

MRI guidance technology development in a large animal model for hyperlocal analgesics delivery to the epidural space and dorsal root ganglion

BACKGROUND

Development of new analgesic drugs or gene therapy vectors for spinal delivery will be facilitated by "hyperlocal" targeting of small therapeutic injectate volumes if spine imaging technology can be used that is ready for future clinical translation.

NEW METHOD

This study provides methods for MRI-guided drug delivery to the periganglionic epidural space and the dorsal root ganglion (DRG) in the Yucatan swine.

RESULTS

Phantom studies showed artifact-corrected needle localization with frequency encoding parallel to the needle shaft, while maximizing bandwidth (125 KHz) minimized needle artifact. A custom constructed 8-12 element surface coil (phased array) wrapped over the spine in conjunction with lateral recumbent positioning achieved diagnostic quality signal to noise ratio at the depth of the DRG and afforded transforaminal access via anterolateral or posterolateral vectors, as well as interlaminar access. Swine epidural anatomy was homologous with human anatomy. Injectate containing 2% gadolinium allowed imaging of injectate volumes in increments as small as 10 microliters and discrimination of epidural flow from intraparenchymal injectate delivery into a DRG. All technical and technological elements of the procedure appear clinically translatable.

COMPARISON WITH EXISTING METHODS

Computed tomographic or fluoroscopic guidance cannot directly visualize drug delivery into the DRG due to contrast medium toxicity, nor reliably identify epidural injection volumes of < 50 microliters.

CONCLUSIONS

MRI-guided hyperlocal delivery in swine provides a translatable and faithful model of future human spinal novel drug- or gene therapy vector delivery.

Invasive Pulmonary Aspergillosis in the Epidural Space in a Patient with Acute Myelogenous Leukemia with Myelodysplasia-related Changes: A Case Study and Literature Review of Vertebral Aspergillosis in Japan

Vertebral aspergillosis is a rare infectious disease with a high mortality rate. We herein report a 70-year-old woman with acute myelogenous leukemia with myelodysplasia-related changes, nontuberculous mycobacteriosis, and bronchiectasis who presented with a fever and cough. Her clinical symptoms and laboratory test results suggested febrile neutropenia and pneumonia. However, her clinical course was further complicated by lower extremity weakness. Magnetic resonance imaging of the spine showed consolidation contiguously spreading toward the epidural space between the T4 and T5. Cytological testing of the pleural effusion revealed Aspergillus fumigatus. We also review and summarize previously reported cases of vertebral aspergillosis in Japan.

Is a Retrolaminar Approach to the Thoracic Paravertebral Space Possible?: A Human Cadaveric Study

BACKGROUND AND OBJECTIVES

The retrolaminar block (RB) is used for truncal analgesia, but its mechanism of neural blockade remains obscure. We sought to learn the pattern of local anesthetic spread after thoracic RB using cadaveric models.

METHODS

In 8 fresh cadavers, an ultrasound-guided T4 RB was performed with 20 mL of methylene blue 1% and bupivacaine 0.5%. For comparison, an RB at T9 in 1 cadaver and a T4 thoracic paravertebral block in another cadaver were performed. Subsequently, posterior and anterior thoracic dissections were performed to examination where the dye spread.

RESULTS

After T4 RB, dye was noted to spread in the ipsilateral retrolaminar plane (all 8 cadavers, median cephalad spread 3.5 cm, caudad spread 10.7 cm, lateral spread 2.5 cm), the contralateral retrolaminar plane (6 cadavers), the paravertebral space (5 cadavers, median of 3 segments, T3-T5), the intercostal space (5 cadavers, median of 3.5 cm laterally), the T4 epidural space (6 cadavers), and the intervertebral foramina (4 cadavers, median of 2 segments, T4-T5). After T9 retrolaminar injection, dye was noted in the ipsilateral retrolaminar plane (5.5 cm cephalad, 13.5 cm caudad, and 2.5 cm lateral), the contralateral retrolaminar plane, and the epidural space. Dye after T4 traditional paravertebral block spread to T1-T6 paravertebral space with 15-cm lateral spread.

CONCLUSIONS

Injectate spread to the paravertebral space, epidural space, intercostal space, and intervertebral foramina is possible in the RB but is quite variable. In comparison to the thoracic paravertebral block, injectate spread within the paravertebral space is more limited.

Observational Study Using Ultrasound to Assess Midline Labor Epidural Analgesia Placement and Analgesic Efficacy

OBJECTIVES

Labor epidural analgesia failure may relate to nonmidline placement of epidural catheters. We hypothesized that greater deviations of the epidural catheter insertion point from the ultrasound (US)-determined midline would be associated with less effective labor analgesia.

METHODS

A prospective ethically approved cohort study was conducted. Fifty-two healthy average-sized women receiving labor epidural analgesia, inserted by the landmark technique, were approached after delivery. Immediately after removing the epidural catheter, we determined the epidural space midline using US and compared it to the epidural catheter insertion point and to the patient-identified midline (assessed by a pinprick in 1-mm increments). Correlations between the US midline-to-catheter insertion point distance and additional epidural local anesthetic requirements (primary outcome), pain verbal numeric rating scale scores (0-10) 1 hour after epidural insertion, and maternal satisfaction with analgesia were determined. The differences in distances were assessed by a Bland-Altman analysis.

RESULTS

There were no significant correlations between the US midline-to-epidural catheter insertion point distance and additional epidural local anesthetic requirements (R²  = 0.138; P = .33), pain verbal numeric rating scale scores 1 hour after the epidural (R²  = 0.121; P = .40) or maternal satisfaction (R²  = 0.085; P = .57). The Bland-Altman analysis revealed that the mean ± SD US midline-to-epidural catheter insertion point distance and patient-identified midline distances were 0.38 ± 0.31 and 0.35 ± 0.46 cm, respectively.

CONCLUSIONS

In our laboring population, the hypothesis that nonmidline epidural insertion is associated with less-effective labor analgesia was not confirmed in this study cohort. We found minimal differences in distances between the US midline to epidural catheter insertion point and US midline to patient-identified midline.