Functional mapping of the lower urinary tract by epidural electrical stimulation of the spinal cord in decerebrated cat model

Several neurologic diseases including spinal cord injury, Parkinson's disease or multiple sclerosis are accompanied by disturbances of the lower urinary tract functions. Clinical data indicates that chronic spinal cord stimulation can improve not only motor function but also ability to store urine and control micturition. Decoding the spinal mechanisms that regulate the functioning of detrusor (Detr) and external urethral sphincter (EUS) muscles is essential for effective neuromodulation therapy in patients with disturbances of micturition. In the present work we performed a mapping of Detr and EUS activity by applying epidural electrical stimulation (EES) at different levels of the spinal cord in decerebrated cat model. The study was performed in 5 adult male cats, evoked potentials were generated by EES aiming to recruit various spinal pathways responsible for LUT and hindlimbs control. Recruitment of Detr occurred mainly with stimulation of the lower thoracic and upper lumbar spinal cord (T13-L1 spinal segments). Responses in the EUS, in general, occurred with stimulation of all the studied sites of the spinal cord, however, a pronounced specificity was noted for the lower lumbar/upper sacral sections (L7-S1 spinal segments). These features were confirmed by comparing the normalized values of the slope angles used to approximate the recruitment curve data by the linear regression method. Thus, these findings are in accordance with our previous data obtained in rats and could be used for development of novel site-specific neuromodulation therapeutic approaches.

Post-traumatic hematoma of the "transdural" virtual space. A possible cause of incorrect surgical treatment of epidural hematomas

The space existing between the external and internal dural layer has been anatomically described as a virtual space; no clear clinical significance has been given to it to date. We hereby describe a case of a child with what was expected to be a purely epidural hematoma, at surgery, was found to be composed of two equally coexistent components, one in the epidural space and the second one between the two dural layers. The recognition of a possible involvement of the transdural space in the case of post-traumatic epidural hematomas is relevant for a correct conclusion of the surgical treatment of epidural hematomas, extensively considered basic practice among neurosurgical procedures.

Evaluation of the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume, in rabbits (Oryctolagus Cuniculus)

Veterinary care for rabbits has been growing, and, consequently, the anesthetic and analgesic management of this species must be improved. The aim of the present study was to evaluate the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume in rabbits (Oryctolagus Cuniculus). In a prospective, randomized blinded study, six healthy New Zealand rabbits, adults, and weighing from 2.2 kg to 3.8 kg received two treatments, at 1 week intervals: 0.33 mL/kg (treatment I) or 0.05 mL per centimeter of the spine (treatment II) of ioexol epidurally. In both treatments, a peripheral nerve stimulator (2 Hz, 0.25 mA and 0.1 milliseconds) was used to determine the location of the epidural space. Latero-lateral and ventro-dorsal radiographs were taken after five (T5) and twenty-five minutes (T25) of iohexol administration. The epidural space was correctly accessed in 92% of attempts. Treatment I received a smaller volume of contrast than treatment II, 1.0 ± 0.2 mL versus 2.1 ± 0.1 mL (mean ± standard deviation), respectively (p = 0.007). At T5, the cranial progression of the contrast varied between L4 and L5 in treatment I, and L5 and T10 in treatment II. At T25, no contrast was observed in any rabbit. In conclusion, peripheral nerve stimulator aided in accessing the lumbosacral epidural space, and the administration of 0.05 mL per centimeter of the spine resulted in greater cranial progression of contrast.

Teaching NeuroImage: Clinical and Imaging Features of Cobb Syndrome

A 17-year-old boy with typical neurodevelopment presented with 3 months of lower-limb weakness without a history of trauma. Physical examination, plain radiography and a T2-weighted MRI revealed a port-wine stain over the lumbar region, significant scoliosis below the cervical segment, and a multifocal flow void sign (steal phenomenon) from epidural space to dorso-lumbar spine, respectively (Figure 1). CT angiography identified an enhancing dorsal vascular mass with involvement of the spinal canal including destruction of the vertebral body determined to be extensive arteriovenous shunts on digital subtraction angiography (DSA) (Figure 2).

Endoscopic transoral resection for an upper cervical chordoma in a pediatric patient

BACKGROUND

Upper cervical chordoma (UCC) is a rare disease, and although transoral approaches are the methods of choice, minimally invasive techniques have not been established.

METHOD

We report the successful use of endoscopic transoral surgery for upper cervical chordoma at the C1-3 levels in the midline epidural space in an 8-year-old girl who presented with neck pain and quadriplegia. Three months after occipitocervical posterior fixation, endoscopic transoral surgery was performed and the tumor was nearly totally removed.

CONCLUSION

Endoscopic transoral surgery in pediatric patients with UCCs is a minimally invasive and safe technique.

Implantation of Surgical Paddle Electrodes Using Percutaneous Biportal-Endoscopic Technique for Spinal Cord Stimulation: An Anatomical Feasibility Study in Human Cadavers

BACKGROUND

Spinal cord stimulation is a technique in which different types of electrodes are placed in the spinal epidural space for neuromodulation. Surgical paddle electrodes (SEs) are usually implanted by a surgeon by performing open surgery with laminectomy. Recent advances in endoscopic spine surgery provide another option for minimally invasive SE implantation.

OBJECTIVES

This anatomical study aims to examine the feasibility of implanting SEs in thoracic and cervical spine segments, discussing the specific advantages and disadvantages compared with previously reported methods.

STUDY DESIGN

Laboratory study with Institutional Review Board No B2023-056.

METHODS

Four fresh adult cadavers (2 women, 2 men) were operated on in this study. The posterior unilateral biportal endoscopic surgical approach, the accessibility to the intraspinal epidural space, and the technical possibilities and limitations of implantation of SEs were evaluated, as well as the surgical duration and complications.

RESULTS

All the planned steps of the operation were successfully accomplished in all 4 cadavers. A total of 8 electrodes were successfully implanted through the working portal. Among them, 4 were located in the cervical segment and 4 in the thoracic segment. The proper position of the electrodes was also verified by fluoroscopy. No rupture of dura occurred during the operation. Except for the first cadaver, the duration of surgery did not exceed 1 hour.

LIMITATIONS

Anatomical study on human cadavers, the quantity of cadavers, and the steep learning curve.

CONCLUSIONS

The results of this anatomical study show that the SEs can be satisfactorily implanted in cervical and thoracic segments using the unilateral biportal endoscopic technique.

Paralysis under pressure

Treating cardiovascular paralysis with epidural electrical neuromodulation.

The Antinociceptive Effect of Magnesium Sulphate Administered in the Epidural Space in Standing Horses

To study the antinociceptive properties of epidural magnesium sulphate (MgSO₄) in standing horses Experimental, placebo-controlled, masked, cross-over A group of six healthy horses Through an epidural catheter, 1 mg kg ^-1 MgSO₄ (treatment Mg) diluted to a volume of 15 mL or the same volume of saline (treatment S) was administered over 15 minutes. Electrical, thermal and mechanical nociceptive thresholds were determined on the pelvic limb before and 20, 40, 60, 80, 100, 120, 140, 160 and 180 minutes after the start of the injection. Heart rate (HR) and respiratory frequency (f_R) were recorded every 10 minutes. Blood samples were collected before treatment and every 30 minutes throughout the study period. Data were assessed for normality using a Shapiro-Wilk test. A linear mixed model with horse as random effect and time, treatment and their interaction as fixed effects was used. Treatments were compared at 20, 60, 120 and 180 minutes using the Wilcoxon rank sum test stratified for horse (global α = 0.05, with Bonferroni correction α = 0.0125). Epidural MgSO₄ caused a significant increase in the electrical threshold (mA) (P = .0001), but no significant differences in thermal and mechanical nociceptive thresholds. During the injection of MgSO_4, two horses collapsed. One stood up within 20 minutes and was able to continue the study, the second one was excluded. A significant difference was found for HR at T180 (Mg 44 ± 23 beats minute^-1; S 32 ± 9 beats minute^-1) (P = .0090). Epidural administration of MgSO₄ caused an increase in the electrical threshold of the pelvic limbs of horses. Caution is warranted however, as with the current dose, 2 horses collapsed.

Correlation Between the Extent of Injectate Spread and Clinical Outcomes in Cervical Interlaminar Epidural Injection

BACKGROUND

Cervical interlaminar epidural injection (CILEI) is commonly used to treat acute or chronic pain that affects the head, neck, and upper extremities. Thus far, studies on CILEI have focused on determining the optimal volume of contrast medium or analyzing the spread of contrast medium during a CILEI. To our knowledge, few studies have attempted to assess the correlation between epidurogram patterns and clinical outcomes of CILEI.

OBJECTIVES

This study aimed to investigate the relationship between contrast medium spread and pain relief after a CILEI in patients who complained of neck and/or unilateral upper extremity pain.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary university hospital.

METHODS

Patient demographics, pain duration, and radiographic findings, including cervical simple radiograph and magnetic resonance imaging, were reviewed from medical records. The spread pattern of contrast medium during a CILEI was analyzed based on anteroposterior (AP) and lateral fluoroscopic views. The spread pattern in the AP view was classified into 4 categories using predetermined anatomical references, including the medial border, bisector, and lateral border of the articular pillar at the targeted vertebral level. The spread pattern in the lateral view was divided into 2 groups based on whether the contrast medium was present at the ventral epidural space. Every CILEI procedure was performed under fluoroscopic guidance by skilled experts. A responsive outcome was defined as a reduction in the numeric rating scale for pain by more than 50% at one month postoperatively compared to preoperatively.

RESULTS

Among 656 patients, 526 were excluded from the analysis according to predetermined criteria. The remaining 130 patients were analyzed, and 78 (60%) patients showed responsive results one month after a CILEI. According to a multivariable logistic regression analysis, the negative predictors of a CILEI were long symptom duration (P = 0.045), high grade of central stenosis (P = 0.022), and limited spread of contrast medium solely within the central canal in the AP view (P = 0.008).

LIMITATIONS

The limitations of this study include its retrospective design, absence of clinical parameters other than pain intensity, and short follow-up period.

CONCLUSIONS

If the duration of symptoms is lengthy, central stenosis is severe, or contrast medium spread is limitedly solely within the central canal and does not reach the dorsal root ganglion any further, the outcome after a CILEI is likely to be poor. Therefore, efforts should be made to spread injectate around the dorsal root ganglion at the target level.

Effect of Spinal Cord Burst Stimulation vs Placebo Stimulation on Disability in Patients With Chronic Radicular Pain After Lumbar Spine Surgery: A Randomized Clinical Trial

IMPORTANCE

The use of spinal cord stimulation for chronic pain after lumbar spine surgery is increasing, yet rigorous evidence of its efficacy is lacking.

OBJECTIVE

To investigate the efficacy of spinal cord burst stimulation, which involves the placement of an implantable pulse generator connected to electrodes with leads that travel into the epidural space posterior to the spinal cord dorsal columns, in patients with chronic radiculopathy after surgery for degenerative lumbar spine disorders.

DESIGN, SETTING, AND PARTICIPANTS

This placebo-controlled, crossover, randomized clinical trial in 50 patients was conducted at St Olavs University Hospital in Norway, with study enrollment from September 5, 2018, through April 28, 2021. The date of final follow-up was May 20, 2022.

INTERVENTIONS

Patients underwent two 3-month periods with spinal cord burst stimulation and two 3-month periods with placebo stimulation in a randomized order. Burst stimulation consisted of closely spaced, high-frequency electrical stimuli delivered to the spinal cord. The stimulus consisted of a 40-Hz burst mode of constant-current stimuli with 4 spikes per burst and an amplitude corresponding to 50% to 70% of the paresthesia perception threshold.

MAIN OUTCOMES AND MEASURES

The primary outcome was difference in change from baseline in the self-reported Oswestry Disability Index (ODI; range, 0 points [no disability] to 100 points [maximum disability]; the minimal clinically important difference was 10 points) score between periods with burst stimulation and placebo stimulation. The secondary outcomes were leg and back pain, quality of life, physical activity levels, and adverse events.

RESULTS

Among 50 patients who were randomized (mean age, 52.2 [SD, 9.9] years; 27 [54%] were women), 47 (94%) had at least 1 follow-up ODI score and 42 (84%) completed all stimulation randomization periods and ODI measurements. The mean ODI score at baseline was 44.7 points and the mean changes in ODI score were -10.6 points for the burst stimulation periods and -9.3 points for the placebo stimulation periods, resulting in a mean between-group difference of -1.3 points (95% CI, -3.9 to 1.3 points; P = .32). None of the prespecified secondary outcomes showed a significant difference. Nine patients (18%) experienced adverse events, including 4 (8%) who required surgical revision of the implanted system.

CONCLUSIONS AND RELEVANCE

Among patients with chronic radicular pain after lumbar spine surgery, spinal cord burst stimulation, compared with placebo stimulation, after placement of a spinal cord stimulator resulted in no significant difference in the change from baseline in self-reported back pain-related disability.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03546738.

Epidural abscess formation with an atypical pathogen following epidural steroid injection: A case report

RATIONALE

Subcutaneous and epidural abscesses following epidural injection are a serious but rare complication. Epidural abscesses are typically caused by Staphylococcus aureus bacterial infection. In this case presented here, the causative bacterium was Enterococcus faecalis.

PATIENT CONCERNS

A 67-year-old woman having chronic lower back and right leg pain with past history of 20 years of rheumatoid arthritis, diabetes mellitus, and osteoporosis (T-score: -2.7) visited the outpatient pain clinic. Magnetic resonance imaging (MRI) revealed L4-5 right central disc extrusion with inferior migration. We performed a continuous epidural block for 7 days without complications. After 10 days, she presented with worsened low back pain, erythematous skin change on the lower back, chilling, and elevated serum acute phase reactants.

DIAGNOSIS

The diagnosis was subsequently confirmed by MRI suggesting subcutaneous and epidural abscess. Blood and pus cultures showed the growth of E. faecalis.

INTERVENTIONS

Pigtail catheter drainage was performed and intravenous antibiotics (ampicillin-sulbactam) targeting E. faecalis were applied for 3 weeks. Oral antibiotics (amoxicillin/potassium clavulanate) were applied for 6 weeks after discharge.

OUTCOMES

At the 2-month follow-up, improvement in both the clinical condition and serum acute phase reactants levels were noted.

LESSONS

Epidural injection can lead to a subcutaneous abscess that is further extended into the epidural space. One of the key factors is the presence of comorbid conditions, including diabetes mellitus and prolonged steroid usage due to rheumatoid arthritis.

High-Resolution Spinal Motor Mapping Using Thoracic Spinal Cord Stimulation in Patients With Chronic Pain

BACKGROUND

High-resolution spinal cord stimulation (HR-SCS) paddle can stimulate medial-dorsal columns and extend stimulation coverage to the laterally positioned spinal targets.

OBJECTIVE

To investigate the medio-lateral selectivity of an HR-SCS paddle in patients with chronic pain.

METHODS

During standard-of-care spinal cord stimulation (SCS) placement, epidurally evoked electromyography and antidromic dorsal column-evoked potentials were recorded in 12 subjects using an HR-SCS paddle with 8 medio-lateral sites spanning the full epidural width at thoracic T9-12 and a commercial paddle consecutively.

RESULTS

Recruitment maps were aligned with respect to physiological midline which was overlapping with anatomic midline in 10 of 11 cases. Overlapping contacts between the HR-SCS and commercial paddles exhibited similar patterns while HR-SCS demonstrated higher precision targeting of certain dermatomes. Spinal motor maps showed that the lateral contacts triggered stronger responses in medial gastrocnemius, adductor magnus, and tibialis anterior while the medial contacts triggered stronger responses in gluteus maximus and adductor hallucis. The time-locked popliteal fossa responses indicated ipsilateral activation by HR-SCS at the lateral contacts and bilateral activation at the medial contacts with stronger ipsilateral responses.

CONCLUSION

This study is the first to perform high-resolution medio-lateral SCS mapping in patients with chronic pain. These results show promise that HR-SCS may provide additional ipsilateral recruitment within the extremities which improve targeting of focal pain in the lower extremities. Furthermore, this study supports the functional use of intraoperative neuromonitoring as a decision tool to determine physiological midline in thoracic SCS surgeries and provides a full methodological framework.

Accidental administration of tranexamic acid into the epidural space: a case report

PURPOSE

Tranexamic acid administration into the epidural space has not been previously reported. We describe our experience managing and investigating a drug error involving incorrect route of tranexamic acid administration through an epidural catheter.

CLINICAL FEATURES

A syringe containing tranexamic acid, intended for intravenous bolus and infusion intraoperatively using microbore tubing, was inadvertently attached to an epidural catheter via the Luer-type connector on the microbore tubing and epidural adapter.

CONCLUSIONS

Saline lavage of the epidural space may be considered if tranexamic acid has been administered into the epidural space. Early multidisciplinary team involvement combined with repeated postevent neurologic monitoring is recommended to guide therapy. Adoption of neuraxial route-specific connectors, when available, may be warranted to reduce Luer-type misconnections.

FBG-Based Soft System for Assisted Epidural Anesthesia: Design Optimization and Clinical Assessment

Fiber Bragg grating sensors (FBGs) are considered a valid sensing solution for a variety of medical applications. The last decade witnessed the exploitation of these sensors in applications ranging from minimally invasive surgery to biomechanics and monitoring physiological parameters. Recently, preliminary studies investigated the potential impact of FBGs in the management of epidural procedures by detecting when the needle reaches the epidural space with the loss of resistance (LOR) technique. In this article, we propose a soft and flexible FBG-based system capable of detecting the LOR, we optimized the solution by considering different designs and materials, and we assessed the feasibility of the optimized soft sensor (SS) in clinical settings. The proposed SS addresses some of the open challenges in the use of a sensing solution during epidural punctures: it has high sensitivity, it is non-invasive, the sensing element does not need to be inserted within the needle, and the clinician can follow the standard clinical practice. Our analysis highlights how the material and the design impact the system response, and thus its performance in this scenario. We also demonstrated the system’s feasibility of detecting the LOR during epidural procedures.

Advances in Epidural Spinal Cord Stimulation to Restore Function after Spinal Cord Injury: History and Systematic Review

Epidural spinal cord stimulation (eSCS) has been recently recognized as a potential therapy for chronic spinal cord injury (SCI). eSCS has been shown to uncover residual pathways within the damaged spinal cord. The purpose of this review is to summarize the key findings to date regarding the use of eSCS in SCI. Searches were carried out using MEDLINE, EMBASE, and Web of Science database and reference lists of the included articles. A combination of medical subject heading terms and keywords was used to find studies investigating the use of eSCS in SCI patients to facilitate volitional movement and to restore autonomic function. The risk of bias was assessed using Risk Of Bias In Non-Randomized Studies of Interventions tool for nonrandomized studies. We were able to include 40 articles that met our eligibility criteria. The studies included a total of 184 patient experiences with incomplete or complete SCI. The majority of the studies used the Medtronic 16 paddle lead. Around half of the studies reported lead placement between T11- L1. We included studies that assessed motor (n = 28), autonomic (n = 13), and other outcomes (n = 10). The majority of the studies reported improvement in outcomes assessed. The wide range of included outcomes demonstrates the effectiveness of eSCS in treating a diverse SCI population. However, the current studies cannot definitively conclude which patients benefit the most from this intervention. Further study in this area is needed to allow improvement of the eSCS technology and allow it to be more widely available for chronic SCI patients.

Effect of epidural spinal cord stimulation after chronic spinal cord injury on volitional movement and cardiovascular function: study protocol for the phase II open label controlled E-STAND trial

INTRODUCTION

Spinal cord injury (SCI) leads to significant changes in morbidity, mortality and quality of life (QOL). Currently, there are no effective therapies to restore function after chronic SCI. Preliminary studies have indicated that epidural spinal cord stimulation (eSCS) is a promising therapy to improve motor control and autonomic function for patients with chronic SCI. The aim of this study is to assess the effects of tonic eSCS after chronic SCI on quantitative outcomes of volitional movement and cardiovascular function. Our secondary objective is to optimise spinal cord stimulation parameters for volitional movement.

METHODS AND ANALYSIS

The Epidural Stimulation After Neurologic Damage (ESTAND) trial is a phase II single-site self-controlled trial of epidural stimulation with the goal of restoring volitional movement and autonomic function after motor complete SCI. Participants undergo epidural stimulator implantation and are followed up over 15 months while completing at-home, mobile application-based movement testing. The primary outcome measure integrates quantity of volitional movement and similarity to normal controls using the volitional response index (VRI) and the modified Brain Motor Control Assessment. The mobile application is a custom-designed platform to support participant response and a kinematic task to optimise the settings for each participant. The application optimises stimulation settings by evaluating the parameter space using movement data collected from the tablet application and accelerometers. A subgroup of participants with cardiovascular dysautonomia are included for optimisation of blood pressure stabilisation. Indirect effects of stimulation on cardiovascular function, pain, sexual function, bowel/bladder, QOL and psychiatric measures are analysed to assess generalisability of this targeted intervention.

ETHICS AND DISSEMINATION

This study has been approved after full review by the Minneapolis Medical Research Foundation Institutional Review Board and by the Minneapolis VA Health Care System. This project has received Food and Drug Administration investigational device exemption approval. Trial results will be disseminated through peer-reviewed publications, conference presentations and seminars.

TRIAL REGISTRATION NUMBER

NCT03026816.

Epidural administration of 2% Mepivacaine after spinal anesthesia does not prevent intraoperative nausea and vomiting during cesarean section: A prospective, double-blinded, randomized controlled trial

BACKGROUND

Intraoperative nausea and vomiting (IONV) is a common symptom during cesarean section (CS) delivery causing significant discomfort to patients. Combined spinal and epidural anesthesia (CSEA) can provide both intraoperative anesthesia and postoperative analgesia. During CSEA, it is reasonable to administer local anesthetics to the epidural space before patient complaints to compensate for the diminished effect of spinal anesthesia. Therefore, we hypothesized that intraoperative epidural administration of 2% mepivacaine would reduce the incidence of IONV.

METHODS

Patients who were scheduled for elective CS were randomly allocated to 2 groups. Patients and all clinical staff except for an attending anesthesiologist were blinded to the allocation. After the epidural catheter was inserted at the T11-12 or T12-L1 interspace, spinal anesthesia was performed at the L2-3 or L3-4 interspace to intrathecally administer 10 mg of 0.5% hyperbaric bupivacaine. Twenty min after spinal anesthesia, either 5 mL of 2% mepivacaine (group M) or saline (group S) was administered through an epidural catheter. Vasopressors were administered prophylactically to keep both the systolic blood pressure ≥ 80 % of the baseline value with the absolute value ≥ 90 mm Hg and the mean blood pressure ≥ 60 mm Hg. The primary endpoint was the incidence of IONV. The secondary endpoints were degree of nausea, the degree and incidence of pain, and Bromage score.

RESULTS

Ninety patients were randomized, and 3 patients were excluded from the final analysis. There was no significant difference in the incidence of IONV between the groups (58% in group M and 61% in group S, respectively, P = .82). In contrast, the incidence and degree of intraoperative pain in group M were significantly lower compared to group S. In addition, the incidence of rescue epidural administration of fentanyl (18% vs 47%) or mepivacaine (2.3% vs 25%) for intraoperative pain was lower in group M compared to group S.

CONCLUSIONS

Our results indicate that epidural administration of 2% mepivacaine 20 minutes after spinal anesthesia does not reduce the incidence of IONV in CS under CSEA. However, intraoperative epidural administration of 2% mepivacaine was found to improve intraoperative pain.

Preoperative Thoracic Spine Magnetic Resonance Imaging for Spinal Cord Stimulation: Should Such a Recommendation Be an Absolute Requirement?

OBJECTIVE

Current published guidelines recommend advanced imaging, specifically, thoracic magnetic resonance imaging (MRI), prior to implantation of epidural paddle spinal cord stimulator (SCS) leads. Preoperative imaging may affect surgical approach to minimize risk of complications. We aimed to assess the impact of preoperative thoracic MRI on surgical planning in a large series of surgical paddle SCS lead placements in a real-world setting.

MATERIALS AND METHODS

This is a retrospective study of a prospectively maintained data base of 160 patients treated by SCS with awake thoracic surgical paddle lead placement in a single academic functional neurosurgery center from 2013 to 2021. All patients had a thoracic MRI prior to implantation. Abnormal MRI findings were reviewed to determine their potential impact on the safety of surgical paddle lead placement. A minor impact was defined as anatomical areas to avoid with paddle lead placement. Major impacts included significant deviations from standard approach to electrode placement.

RESULTS

None of the 160 patients had signs or symptoms referable to thoracic spine pathology prior to lead implant. Sixty-seven had abnormal thoracic MRI findings, and 36 had abnormal MRI findings that impacted surgical planning. Thirty-one patients had MRI findings with minor impact. Five patients (more than 3%) had findings with major impact.

CONCLUSIONS

This is the largest case series assessing the impact of preoperative thoracic MRI on surgical planning for patients undergoing paddle SCS placement. Twenty-two percent of patients had MRI findings that impacted surgical planning with 3% requiring additional surgical decompression for safe paddle lead placement. Without advanced imaging to inform surgical planning, unnecessary risk may have been placed on these patients. Although such imaging has been recommended by consensus committees in published guidelines, our study is the first to present a large institutional experience of real-world data that demonstrates its importance.

Preoperative Transvenous Liquid Embolization for a Symptomatic Lumbar Spinal Epidural Varix Mimicking Radiculopathy

BACKGROUND

Symptomatic spinal epidural veins (SEV) are a rare cause of neurologic dysfunction. Treatment is centered upon addressing the underlying venous pathology to relieve mechanical compression of the neurologic structures. However, open surgical ligation is often associated with considerable blood loss.

OBJECTIVE

We discuss a unique case of a large symptomatic epidural venous varix and potential treatment strategy.

METHODS AND MATERIALS

A 15-year-old female presented with a 1-year history of left L5 radicular pain and weakness. Lumbar MRI demonstrated a central L5/S1 herniated disc and a large extradural anomalous SEV compressing the exiting left L5 nerve root at the L5/S1 neuroformina. The SEV was treated using a transvenous liquid embolic agent providing symptomatic relief. At 16-months follow-up, she reported recurrent symptoms. She ultimately underwent a left L5/S1 MIS decompression without complication.

CONCLUSION

Transvenous liquid embolization of large symptomatic SEV may provide temporary neurologic relief and decrease morbidity associated with open surgical treatment options.

Implanted System for Orthostatic Hypotension in Multiple-System Atrophy

Orthostatic hypotension is a cardinal feature of multiple-system atrophy. The upright posture provokes syncopal episodes that prevent patients from standing and walking for more than brief periods. We implanted a system to restore regulation of blood pressure and enable a patient with multiple-system atrophy to stand and walk after having lost these abilities because of orthostatic hypotension. This system involved epidural electrical stimulation delivered over the thoracic spinal cord with accelerometers that detected changes in body position. (Funded by the Defitech Foundation.).

A man with severed spine is able to walk again following implantation of electrical stimulation device

Patients with devastating spinal cord injuries regained the ability to stand, walk, and perform even more complex motor functions after receiving implants that deliver epidural electrical stimulation.

Epidural spinal stimulation enables global sensorimotor and autonomic function recovery after complete paralysis: 1st study from India

While the loss of sensorimotor and autonomic function often occurs due to multiple trauma and pathologies, spinal cord injury is one of the few traumatic pathologies that severely affects multiple organ systems both upstream and downstream of the injury. Current standard of care therapies primarily maintains health and avoids secondary complications. They do not address the underlying neurological condition. Multiple modalities including spinal neuromodulation have shown promise as potential therapies. The objective of this study was to demonstrate the impact of activity-based neurorehabilitation in presence of epidural spinal stimulation to enable simultaneous global recovery of sensorimotor and autonomic functions in patients with complete motor paralysis due to spinal cord injury. These data are unique in that it quantifies simultaneously changes multiple organ systems within only 2 months of intense activity-based neurorehabilitation when also delivering epidural stimulation consisting of sub-motor threshold stimulation over a period of 12-16 hours/day to enable 'self-training' in 10 patients. Finally, these studies were done in a traditional neurorehabilitation clinical in India using off-the-shelf electrode arrays and pulse generators, thus demonstrating the feasibility of this approach in simultaneously enabling recoveries of multiple physiological organ systems after chronic paralysis and the ability to perform these procedures in a standard, well-controlled clinical environment.

A Pilot Study Implementing a Machine Learning Algorithm to Use Artificial Intelligence to Diagnose Spinal Conditions

BACKGROUND

Chronic spinal pain is the most prevalent chronic disease, with chronic persistent spinal pain lasting longer than one-year reported in 25% to 60% of the patients. Health care expenditures have been escalating and the financial impact on the US economy is growing. Among multiple modalities of treatments available, facet joint interventions and epidural interventions are the most common ones, in addition to surgical interventions and numerous other conservative modalities of treatments. Despite these increasing costs in the diagnosis and management, disability continues to increase. Consequently, algorithmic approaches have been described as providing a disciplined approach to the use of spinal interventional techniques in managing spinal pain. This approach includes evaluative, diagnostic, and therapeutic approaches, which avoids unnecessary care, as well as poorly documented practices.  Recently, techniques involving artificial intelligence and machine learning have been demonstrated to contribute to the improved understanding, diagnosis, and management of both acute and chronic disease in line with well-designed algorithmic approach. The use of artificial intelligence and machine-learning techniques for the diagnosis of spinal pain has not been widely investigated or adopted.

OBJECTIVES

To evaluate whether it is possible to use artificial intelligence via machine learning algorithms to analyze specific data points and to predict the most likely diagnosis related to spinal pain.

STUDY DESIGN

This was a prospective, observational pilot study.

SETTING

A single pain management center in the United States.

METHODS

A total of 246 consecutive patients with spinal pain were enrolled. Patients were given an iPad to complete a Google form with 85 specific data points, including demographic information, type of pain, pain score, pain location, pain duration, and functional status scores. The data were then input into a decision tree machine learning software program that attempted to learn which data points were most likely to correspond to the practitioner-assigned diagnosis. These outcomes were then compared with the practitioner-assigned diagnosis in the chart.

RESULTS

The average age of the included patients was 57.4 years (range, 18-91 years). The majority of patients were women and the average pain history was approximately 2 years. The most common practitioner-assigned diagnoses included lumbar radiculopathy and lumbar facet disease/spondylosis. Comparison of the software-predicted diagnosis based on reported symptoms with practitioner-assigned diagnosis revealed that the software was accurate approximately 72% of the time.

LIMITATIONS

Additional studies are needed to expand the data set, confirm the predictive ability of the data set, and determine whether it is broadly applicable across pain practices.

CONCLUSIONS

Software-predicted diagnoses based on the data from patients with spinal pain had an accuracy rate of 72%, suggesting promise for augmented decision making using artificial intelligence in this setting.

Superhydrophilic PLGA-Graft-PVP/PC Nanofiber Membranes for the Prevention of Epidural Adhesion

Background

The frequent occurrence of failed back surgery syndrome (FBSS) seriously affects the quality of life of postoperative lumbar patients. Epidural adhesion is the major factor in FBSS.

Purpose

A safe and effective antiadhesion material is urgently needed.

Methods

A superhydrophilic PLGA-g-PVP/PC nanofiber membrane (NFm) was prepared by electrospinning. FTIR was performed to identify its successful synthesis. Scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and water contact angle measurement were performed. CCK-8 assays were performed in primary rabbit fibroblasts (PRFs) and RAW264.7 cells to explore the cytotoxicity of PLGA-g-PVP/PC NFm. Calcein-AM/PI staining was used to measure the adhesion status in PRFs. ELISA was performed to measure the concentrations of TNF-α and IL-10 in RAW264.7 cells. In addition, the anti-epidural adhesion efficacy of the PLGA-g-PVP/PC NFm was determined in a rabbit model of lumbar laminectomy.

Results

The PLGA-g-PVP/PC NFm exhibited ultrastrong hydrophilicity and an appropriate degradation rate. Based on the results of the CCK-8 assays, PLGA-g-PVP/PC NFm had no cytotoxicity to PRFs and RAW264.7 cells. Calcein-AM/PI staining showed that PLGA-g-PVP/PC NFm could inhibit PRF adhesion. ELISAs showed that PLGA-g-PVP/PC NFm could attenuate lipopolysaccharide-induced macrophage activation. In vivo experiments further confirmed the favorable anti-epidural adhesion effect of PLGA-g-PVP/PC NFm and the lack of a strong inflammatory response.

Conclusion

In this study, PLGA-g-PVP/PC NFm was developed successfully to provide a safe and effective physical barrier for preventing epidural adhesion. PLGA-g-PVP/PC NFm provides a promising strategy for preventing postoperative adhesion and has potential for clinical translation.

Predicting Epidural Space Spread Using Ultrasound Color Doppler Imaging in Interlaminar Epidural Steroid Injection: A Prospective Observational Study

BACKGROUND

While the use of fluoroscopy-guided transforaminal epidural steroid injection (TFESI) to help spread the injectate toward the ventral side has increased, this procedure has a radiation risk. Recently, ultrasound has been widely used in the medical field; among ultrasound methods, color Doppler is useful for predicting the direction of the injectate.

OBJECTIVE

This study describes a novel technique employing color Doppler to help predict epidural space spread in interlaminar epidural steroid injection (ILESI).

STUDY DESIGN

Prospective observational study.

SETTING

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

METHODS

We enrolled 35 patients scheduled for lumbar epidural steroid injection (ESI).  Ultrasound-guided epidural lateral parasagittal interlaminar injection was performed and real-time images using color Doppler were recorded during injections of 5 mL of 0.1% ropivacaine containing contrast dye with dexamethasone 5 mg (1 mL). Fluoroscopy-guided TFESI was performed if it was difficult to perform the procedure based on ultrasound images.

RESULTS

The analysis included 30 images from 30 patients. The observed sensitivity, specificity, positive predictive value, and negative predictive values of the ultrasound color Doppler were 100%, 89.5%, 84.6%, and 100%, respectively. The agreement with ultrasound color Doppler was 93.3%.

LIMITATIONS

The sample size was relatively small.

CONCLUSION

The main advantage of ultrasound-guided ILESI is the lack of radiation exposure and contrast medium requirement. Color Doppler may be a reliable imaging modality to predict epidural space spread during ultrasound-guided ILESI. It is worth predicting the spread in the anterior epidural space (AES) by first attempting ultrasound-guided ESI. If the injectate has not spread to the AES, fluoroscopy-guided TFESI may be a good option after confirming improvement of the patient's symptoms.

Post-traumatic temporal bone pneumatocele presenting after aggressive Valsalva

We report a case of a temporal bone pneumatocele with full-thickness erosion of the cranium associated with aggressive nose blowing. This condition presented 9 years after traumatic fracture of the temporal bone. There are 17 reported cases of mastoid sinus hyperpneumatisation in the literature. Eleven of the 17 are associated with Valsalva manoeuvres or elevated middle ear pressure. However, no other cases of full-thickness erosion at the site of a former fracture have been reported. We propose that the fracture, in combination with elevated mastoid sinus pressure from aggressive nose blowing, led to escape and trapping of pressurised air in the epidural and subcutaneous spaces, which resulted in bone erosion.

Epidural spinal cord stimulation as an intervention for motor recovery after motor complete spinal cord injury

Spinal cord injury (SCI) commonly results in permanent loss of motor, sensory, and autonomic function. Recent clinical studies have shown that epidural spinal cord stimulation may provide a beneficial adjunct for restoring lower extremity and other neurological functions. Herein, we review the recent clinical advances of lumbosacral epidural stimulation for restoration of sensorimotor function in individuals with motor complete SCI and we discuss the putative neural pathways involved in this promising neurorehabilitative approach. We focus on three main sections: review recent clinical results for locomotor restoration in complete SCI; discuss the contemporary understanding of electrical neuromodulation and signal transduction pathways involved in spinal locomotor networks; and review current challenges of motor system modulation and future directions toward integrative neurorestoration. The current understanding is that initial depolarization occurs at the level of large diameter dorsal root proprioceptive afferents that when integrated with interneuronal and latent residual supraspinal translesional connections can recruit locomotor centers and augment downstream motor units. Spinal epidural stimulation can initiate excitability changes in spinal networks and supraspinal networks. Different stimulation parameters can facilitate standing or stepping, and it may also have potential for augmenting myriad other sensorimotor and autonomic functions. More comprehensive investigation of the mechanisms that mediate the transformation of dysfunctional spinal networks to higher functional states with a greater focus on integrated systems-based control system may reveal the key mechanisms underlying neurological augmentation and motor restoration after severe paralysis.

[Study on Influencing Factors of the Tip Softness of Epidural Anesthesia Catheter]

This article aims to study the factors affecting the flexibility of the tip of an epidural anesthesia catheter. The flexibility of the tip of the epidural anesthesia catheter was tested with a softness tester from four aspects:raw materials, tip structure, tip processing technology, and the outer diameter of the catheter. Highly flexible and malleable polymer material with a smooth tip, the tip softening process and the proper outer diameter can effectively improve the tip flexibility of the epidural anesthesia catheter.

Optimization of Spinal Cord Stimulation Using Bayesian Preference Learning and Its Validation

Epidural spinal cord stimulation has been reported to partially restore volitional movement and autonomic functions after motor and sensory-complete spinal cord injury (SCI). Modern spinal cord stimulation platforms offer significant flexibility in spatial and temporal parameters of stimulation delivered. Heterogeneity in SCI and injury-related symptoms necessitate stimulation personalization to maximally restore functions. However, the large multi-dimensional stimulation space makes exhaustive tests impossible. In this paper, we present a Bayesian optimization strategy for identifying personalized optimal stimulation patterns based on the participant's expressed preference for stimulation settings. We present companion validation protocols for investigating the credibility of learned preference models. The results obtained for five participants in the E-STAND spinal cord stimulation clinical trial are reported. Personalized preference models produced by the proposed learning and optimization algorithm show that there is more similarity in optimal frequency than in pulse width across participants. Across five participants, the average model prediction accuracy is 71.5% in internal cross-validation and 65.6% in prospective validation. Statistical tests of both validation studies show that the ability of the preference models to correctly predict unseen preference data is significantly greater than chance. The personalized preference models are also shown to be significantly correlated with motor task performance across participants. We show that several aspects in participants' quality of life has been improved over the course of the trial. Overall, the results indicate that the Bayesian preference optimization algorithm could assist clinicians in the systematic programming of individualized therapeutic stimulation settings and improve the therapeutic outcomes.

Does Paramedian Approach Preferentially Secure Optimal Drug Delivery Onto Ventral Epidural Space and Subsequent Superior Clinical Efficacy Over a Dorsal Midline Approach During Cervical Interlaminar Epidural Injection?

BACKGROUND

There is paucity in the literature directly comparing the clinical results between the paramedian and the midline interlaminar cervical epidural injections.

OBJECTIVE

To compare the proportion of ventral epidural spread of injectate and consequent clinical outcome between the paramedian and midline approach during interlaminar epidural injection in patients with axial neck and/or interscapular pain triggered from the underlying cervical spine pathologic condition.

STUDY DESIGN

Retrospective study.

SETTING

Primary pain clinic and spine hospital.

METHODS

Two hundred and twenty-three patients with axial neck and/or interscapular pain due to cervical problem underwent interlaminar epidural injection through either a paramedian approach (PM group, n = 93) or a midline approach (ML group, n = 130). We compared the portion of ventral epidural filling, Numeric Rating Scale (NRS), and McNab criteria between both groups. The NRS and McNab criteria were also separately compared between the ventrally spread (VS) group and non-ventral spread (non-VS) group inside each PM and ML group, respectively, at 2 weeks and 10 weeks post-injection.

RESULTS

The PM group showed a significantly higher proportion of ventral spread, successful NRS reduction, and satisfactory McNab criteria than the ML group at 10 weeks. In the PM group, the VS group showed the same results as above compared to the non-VS group.

LIMITATIONS

A retrospective analysis based on the relatively short-term follow-up period clinical results.

CONCLUSIONS

The paramedian approach showed the better direct injectate transfer over the ventral epidural space and subsequently superior clinical efficacy for the patients suffering from axial neck and/or interscapular pain secondary to cervical spine problems.

Magnetic resonance imaging of cerebrospinal fluid spread in the epidural space and postdural puncture headache in obstetrics: A proof-of-concept study

BACKGROUND

Currently, performing an epidural blood patch (EBP) for postdural puncture headache (PDPH) remains a subjective clinical decision. An evidence-based protocol may be of value in identifying women at high risk of developing a severe PDPH.

OBJECTIVE

To investigate a potential correlation between the extent of CSF spread in the epidural space, as noted on Magnetic Resonance Imaging (MRI), and the likelihood of development of severe PDPH in obstetric patients.

DESIGN

A prospective double-blind quasi-observational study.

SETTING

Eight tertiary obstetric units, from NHS hospitals.

PATIENTS

Parturients with accidental dural puncture (ADP) underwent T1 and T2-weighted MRI scans of the brain and lumbar spine within 48 h after delivery. All women were followed up, daily, for 1 week.

MAIN OUTCOME MEASURES

For each woman, a PDPH severity score was calculated using a four-point Verbal Reporting Scale (none = 0, mild = 1, moderate = 2, severe = 3), with additional points awarded for visual, auditory and emetic symptoms. MRIs were reported by a neuroradiologist, blind to the patient details, using a predefined MRI score.

RESULTS

Twenty-two parturients were recruited; 86% (n=19) developed PDPH and 10 of these (53%) required an EBP. The median (range) time for the onset of PDPH was 24 (4 to 126) hours. The median (range) cumulative PDPH severity score was 10 (0 to 21), whereas, the median (range) MRI score was 2.5 (0 to 12). Spearman (rs) analysis identified a significant positive correlation (rs = 0.46; P = 0.024) between cumulative PDPH severity and MRI scores. Of all the radiological features identified in an MRI (lumbar dural shift, caudal brain displacement, epidural or intrathecal blood), the presence of intrathecal blood was most strongly correlated with PDPH severity (P = 0.043).

CONCLUSION

Following an ADP, the extent of CSF spread in the epidural space correlates with the severity of subsequent PDPH.

CLINICAL TRIAL NUMBER AND REGISTRY URL

ISRCTN14959004, https://www.isrctn.com/.

Subcutaneous Emphysema, Pneumomediastinum and Spinal Epidural Emphysema As Complications of Violent Coughing: A Case Report

Spontaneous pneumomediastinum (SPM) is a rare condition characterized by chest pain of sudden- onset, difficulty breathing, dysphagia, dysphonia, and subcutaneous emphysema, which are some-times -accompanied by pain in the neck or back. This condition typically has a benign character that limits itself, and supportive therapy is all that is needed; however, life-threatening consequences may occur, such as upper respiratory tract obstruction, esophageal injury, and tracheal damage, requiring surgery. We report here a man aged 19 years who coughed vigorously due to acute allergic asthma, which lead to subcutaneous emphysema starting from the neck down to the chest, mediastinum and spinal epidural space. This case report stresses the importance of including SPM in the differential diagnosis of cough and chest pain in the young.

Meniscus Sign: A Test for the Confirmation of Correct Placement of Epidural Catheter

BACKGROUND

Localization of epidural space has no clear-cut end point like during subarachnoid block, making it an enigma to the anaesthetist. Confirmation of correct placement of the catheter is desirable in order to prevent failure, high or total spinal when large amount of local anaesthetic agent is inadvertently injected in the intrathecal space, subdural block and lastly local anaesthesia systemic toxicity. This study evaluated the use of meniscus sign to confirm correct placement of epidural catheter.

MATERIALS AND METHOD

A total of 80 patient's scheduled for epidural anaesthesia were recruited into this prospective observational study. The epidural space was located using the loss of resistance to air (LORA) technique. An epidural catheter was inserted gradually through the Tuohy needle, with its removal, 4cm of catheter left in the space and a test dose of 2% lidocaine with adrenaline was instilled. The presence of meniscus sign on the catheter was used to confirm correct placement. The number of correctly placed epidural catheters, intravascular or peri-dura placements were all noted.

RESULT

Of the 80 patients, meniscus sign confirmed correct epidural catheter placement in 74 of them"(92.5% success)". The study showed 100% success for both sensitivity and specificity when the meniscus sign was used for locating epidural placement.

CONCLUSION

The meniscus sign is a reliable indicator of correct epidural catheter placement, with high sensitivity and specificity.

Epidural Interventions in the Management of Chronic Spinal Pain: American Society of Interventional Pain Physicians (ASIPP) Comprehensive Evidence-Based Guidelines

BACKGROUND

Chronic spinal pain is the most prevalent chronic disease with employment of multiple modes of interventional techniques including epidural interventions. Multiple randomized controlled trials (RCTs), observational studies, systematic reviews, and guidelines have been published. The recent review of the utilization patterns and expenditures show that there has been a decline in utilization of epidural injections with decrease in inflation adjusted costs from 2009 to 2018. The American Society of Interventional Pain Physicians (ASIPP) published guidelines for interventional techniques in 2013, and guidelines for facet joint interventions in 2020. Consequently, these guidelines have been prepared to update previously existing guidelines.

OBJECTIVE

To provide evidence-based guidance in performing therapeutic epidural procedures, including caudal, interlaminar in lumbar, cervical, and thoracic spinal regions, transforaminal in lumbar spine, and percutaneous adhesiolysis in the lumbar spine.

METHODS

The methodology utilized included the development of objective and key questions with utilization of trustworthy standards. The literature pertaining to all aspects of epidural interventions was viewed with best evidence synthesis of available literature and  recommendations were provided.

RESULTS

In preparation of the guidelines, extensive literature review was performed. In addition to review of multiple manuscripts in reference to utilization, expenditures, anatomical and pathophysiological considerations, pharmacological and harmful effects of drugs and procedures, for evidence synthesis we have included 47 systematic reviews and 43 RCTs covering all epidural interventions to meet the objectives.The evidence recommendations are as follows: Disc herniation: Based on relevant, high-quality fluoroscopically guided epidural injections, with or without steroids, and results of previous systematic reviews, the evidence is Level I for caudal epidural injections, lumbar interlaminar epidural injections, lumbar transforaminal epidural injections, and cervical interlaminar epidural injections with strong recommendation for long-term effectiveness.The evidence for percutaneous adhesiolysis in managing disc herniation based on one high-quality, placebo-controlled RCT is Level II with moderate to strong recommendation for long-term improvement in patients nonresponsive to conservative management and fluoroscopically guided epidural injections. For thoracic disc herniation, based on one relevant, high-quality RCT of thoracic epidural with fluoroscopic guidance, with or without steroids, the evidence is Level II with moderate to strong recommendation for long-term effectiveness.Spinal stenosis: The evidence based on one high-quality RCT in each category the evidence is Level III to II for fluoroscopically guided caudal epidural injections with moderate to strong recommendation and Level II for fluoroscopically guided lumbar and cervical interlaminar epidural injections with moderate to strong recommendation for long-term effectiveness.The evidence for lumbar transforaminal epidural injections is Level IV to III with moderate recommendation with fluoroscopically guided lumbar transforaminal epidural injections for long-term improvement. The evidence for percutaneous adhesiolysis in lumbar stenosis based on relevant, moderate to high quality RCTs, observational studies, and systematic reviews is Level II with moderate to strong recommendation for long-term improvement after failure of conservative management and fluoroscopically guided epidural injections. Axial discogenic pain: The evidence for axial discogenic pain without facet joint pain or sacroiliac joint pain in the lumbar and cervical spine with fluoroscopically guided caudal, lumbar and cervical interlaminar epidural injections, based on one relevant high quality RCT in each category is Level II with moderate to strong recommendation for long-term improvement, with or without steroids. Post-surgery syndrome: The evidence for lumbar and cervical post-surgery syndrome based on one relevant, high-quality RCT with fluoroscopic guidance for caudal and cervical interlaminar epidural injections, with or without steroids, is Level II with moderate to strong recommendation for long-term improvement. For percutaneous adhesiolysis, based on multiple moderate to high-quality RCTs and systematic reviews, the evidence is Level I with strong recommendation for long-term improvement after failure of conservative management and fluoroscopically guided epidural injections.

LIMITATIONS

The limitations of these guidelines include a continued paucity of high-quality studies for some techniques and various conditions including spinal stenosis, post-surgery syndrome, and discogenic pain.

CONCLUSIONS

These epidural intervention guidelines including percutaneous adhesiolysis were prepared with a comprehensive review of the literature with methodologic quality assessment and determination of level of evidence with strength of recommendations.

Pharmacological disinhibition enhances paced breathing following complete spinal cord injury in rats

Respiratory dysfunction is one of the most devastating and life-threatening deficits that occurs following cervical spinal cord injury (SCI). Assisted breathing with mechanical ventilators is a necessary part of care for many cervical injured individuals, but it is also associated with increased risk of secondary complications such as infection, muscle atrophy and maladaptive plasticity. Pre-clinical studies with epidural stimulation (EDS) have identified it as an alternative/additional method to support adequate lung ventilation without mechanical assistance. The full potential of EDS, however, may be limited by spinal inhibitory mechanisms within the injured spinal cord. The goal of the present work is to assess the potential improvement for EDS in combination with pharmacological disinhibition of spinal circuits following complete high cervical SCI. All experiments were performed in decerebrate, unanesthetized, non-paralyzed (n = 13) and paralyzed (n = 8) adult Sprague-Dawley rats 6 h following a complete C1 transection. The combination of high-frequency EDS (HF-EDS) at the C4 spinal segment with intrathecal delivery of GABA and glycine receptors antagonists (GABAzine and strychnine, respectively) resulted in significantly increased phrenic motor output, tidal volume and amplitude of diaphragm electrical activity compared to HF-EDS alone. Thus, it appears that spinal fast inhibitory mechanisms limit phrenic motor output and present a new neuropharmacological target to improve paced breathing in individuals with cervical SCI.

The Effect of Different Posture on Normal Saline Injection in Optic Nerve Sheath Diameter in Thoracic Epidural Anesthesia

BACKGROUND

Thoracolumbar or caudal epidural anesthesia affects intracranial pressure (ICP) in both animals and humans. Epidural injection increases ICP at least transiently. Measurement of the optic nerve sheath diameter (ONSD) using ultrasonography is one of the noninvasive methods for ICP assessment.

OBJECTIVES

The purpose of this study was to investigate the effect of the different posture during epidural saline injection to the ONSD under awake conditions.

STUDY DESIGN

Prospective, randomized trial.

SETTING

An interventional pain management practice in South Korea.

METHODS

This study included 44 patients receiving thoracic epidural catheterization for pain management after upper abdominal or thoracic surgery. Following successful epidural space confirmation, patients were randomized to receive epidural saline while supine (A group) or in sitting position (B group), respectively. Transorbital sonography was performed for the measurement of the ONSD, and the ONSD was measured at 3 mm posterior to the optic nerve head.

RESULTS

Both A and B groups showed significant increases of ONSD according to time. Mean ONSD values measured at T10, T20, and T40 significantly increased from the baseline value (T0) (*P < 0.05 vs. T0, †P < 0.001 vs. T0, ‡P < 0.005 vs. T0). The mean ONSD values measured at any of the time points and degrees of changes (T10-T0, T20-T0, and T40-T0) between groups A and B did not show any significant changes.

LIMITATIONS

Epidural pressure and ONSD measurement can make this study more reliable. Further study showing changes of epidural pressure with ONSD measurement is required.

CONCLUSIONS

Thoracic epidural injection of 10 mL of normal saline resulted in a significant increase of ONSD compared with the baseline. However, the different posture did not affect the increase of ONSD.

[Incidence of epidural spread after Chayen's approach to lumbar plexus block: a retrospective study]

BACKGROUND AND OBJECTIVES

The lumbar plexus block (LPB) is a key technique for lower limb surgery. All approaches to the LPB involve a number of complications. We hypothesized that Chayen's approach, which involves a more caudal and more lateral needle entry point than the major techniques described in the literature, would be associated with a lower rate of epidural spread.

METHOD

We reviewed the electronic medical records and chart of all adult patients who underwent orthopedic surgery for total hip arthroplasty (THA) and hip hemiarthroplasty due to osteoarthritis and femoral neck fracture with LPB and sciatic nerve block (SNB) between January 1, 2002, and December 31, 2017, in our institute. The LPB was performed according to Chayen's technique using a mixture of mepivacaine and levobupivacaine (total volume, 25 mL) and a SNB by the parasacral approach. The sensory and motor block was evaluated bilaterally during intraoperative and postoperative period.

RESULTS

A total number of 700 patients with American Society of Anesthesiologists (ASA) physical status I to IV who underwent LPB met the inclusion criteria. The LPB and SNB was successfully performed in all patients. Epidural spread was reported in a single patient (0.14%; p <0.05), accounting for an 8.30% reduction compared with the other approaches described in the literature. No other complications were recorded.

CONCLUSIONS

This retrospective study indicates that more caudal and more lateral approach to the LPB, such as the Chayen's approach, is characterized by a lower epidural spread than the other approach to the LPB.

Anatomical and technical factors affecting the neural response to epidural spinal cord stimulation

OBJECTIVE

Spinal cord stimulation (SCS) is a common neurostimulation therapy to treat chronic pain. Computational models represent a valuable tool to study the potential mechanisms of action of SCS and to optimize the design and implementation of SCS technologies. However, it is imperative that these computational models include the appropriate level of detail to accurately predict the neural response to SCS and to correlate model predictions with clinical outcomes. Therefore, the goal of this study was to investigate several anatomic and technical factors that may affect model-based predictions of neural activation during thoracic SCS.

APPROACH

We developed computational models that consisted of detailed finite element models of the lower thoracic spinal cord, surrounding tissues, and implanted SCS electrode arrays. We positioned multicompartment models of sensory axons within the spinal cord to calculate the activation threshold for each sensory axon. We then investigated how activation thresholds changed as a function of several anatomical variables (e.g. spine geometry, dorsal rootlet anatomy), stimulation type (i.e. voltage-controlled vs. current-controlled), electrode impedance, lead position, lead type, and electrical properties of surrounding tissues (e.g. dura conductivity, frequency-dependent conductivity).

MAIN RESULTS

Several anatomic and modeling factors produced significant percent differences or errors in activation thresholds. Rostrocaudal positioning of the cathode with respect to the vertebrae had a large effect (up to 32%) on activation thresholds. Variability in electrode impedance produced significant changes in activation thresholds for voltage-controlled stimulation (38% to 51%), but had little effect on activation thresholds for current-controlled stimulation (less than 13%). Changing the dura conductivity also produced significant differences in activation thresholds.

SIGNIFICANCE

This study demonstrates several anatomic and technical factors that can affect the neural response to SCS. These factors should be considered in clinical implementation and in future computational modeling studies of thoracic SCS.

[Effects of caudal block in pediatric surgical patients: a randomized clinical trial]

BACKGROUND

Surgery generates a neuroendocrine stress response, resulting in undesirable hemodynamic instability, alterations in metabolic response and malfunctioning of the immune system.

OBJECTIVES

The aim of this research was to determine the effectiveness of caudal blocks in intra- and postoperative pain management and in reducing the stress response in children during the same periods.

METHODS

This prospective, randomized clinical trial included 60 patients scheduled for elective herniorrhaphy. One group (n = 30) received general anesthesia and the other (n = 30) received general anesthesia with a caudal block. Hemodynamic parameters, drug consumption and pain intensity were measured. Blood samples for serum glucose and cortisol level were taken before anesthesia induction and after awakening the patient.

RESULTS

Children who received a caudal block had significantly lower serum glucose (p < 0.01), cortisol concentrations (p < 0.01) and pain scores 3 hours (p = 0.002) and 6 hours (p = 0.003) after the operation, greater hemodynamic stability and lower drug consumption. Also, there were no side effects or complications identified in that group.

CONCLUSIONS

The combination of caudal block with general anesthesia is a safe method that leads to less stress, greater hemodynamic stability, lower pain scores and lower consumption of medication.

Comparative Study of Intraspinal Microstimulation and Epidural Spinal Cord Stimulation

Intraspinal microstimulation and epidural spinal cord stimulation can be considered as the technique to restore function following spinal cord injury through further research. In this paper, the automatic brain stereotaxic instrument was used to electrically stimulate the lumbosacral spinal cord (T12-L2 spinal segments) in rats. The motor function regions under intraspinal microstimulation and epidural spinal cord stimulation were measured. Threshold currents and coordinate sites of related motions were recorded. Comparative analysis revealed that the threshold current required for epidural stimulation to induce hindlimb motion was greater. Although the distribution of motor function regions measured by these two methods differed in the type of motion, the segment distribution of each motion were roughly the same. Therefore, if conditions permit, epidural stimulation can be used instead of intraspinal microstimulation to reduce secondary damage to the spinal cord. This provides a reference for locating stimulation sites for epidural spinal cord stimulation.

Comparative Effect of Epidural Administration of Xylazine or Dexmedetomidine on Echocardiographic Dimensions and Cardiac Indices in Clinically Healthy Donkeys (Equus asinus)

The aim of the present study was to assess and compare the changes of the echocardiographic dimensions and cardiac function indices after epidural injection of xylazine or dexmedetomidine in clinically healthy donkeys. In an experimental prospective randomized cross-over study, 10 healthy adult donkeys were injected with saline solution, xylazine (0.20 mg kg^-1), and dexmedetomidine (0.005 mg kg^-1) into the epidural space between the second and third coccygeal vertebrae. Echocardiographic dimensions as well as cardiac function indices were assessed using a 2-3.9 MHz sector transducer, at the left paracostal ultrasonographic window, at zero, 15, 30, 60, 90, 120, and 180 minutes after administration of these medications. Epidural injection of xylazine or dexmedetomidine produced moderate sedation, complete bilateral perineal analgesia, and mild ataxia in all studied donkeys. There was a significant (P < .05) decrease in the interventricular septum thickness at end systole 60 minutes, stroke volume 30-120 minutes, fractional shortening 120 minutes, and ejection fraction 90-120 minutes after administration of xylazine or dexmedetomidine when compared with saline solution. Left ventricular end diastolic volume was significantly (P < .05) increased 60 minutes following epidural injection of dexmedetomidine compared with xylazine and saline solution. There was a significant (P < .05) increase in the left ventricular internal diameter at end diastole 90-120 minutes and left ventricular end systolic volume 60-180 minutes after administration of xylazine or dexmedetomidine in comparison with saline solution. In conclusion, epidural use of xylazine or dexmedetomidine in donkeys induced mild and transient effect on echocardiographic dimensions as well as cardiac function indices. Therefore, care should be taken when such medications are to be administered into the epidural space in donkeys with a pre-anesthetic cardiovascular compromise.

Epidural Spinal Cord Stimulation Promotes Motor Functional Recovery by Enhancing Oligodendrocyte Survival and Differentiation and by Protecting Myelin after Spinal Cord Injury in Rats

Epidural spinal cord stimulation (ESCS) markedly improves motor and sensory function after spinal cord injury (SCI), but the underlying mechanisms are unclear. Here, we investigated whether ESCS affects oligodendrocyte differentiation and its cellular and molecular mechanisms in rats with SCI. ESCS improved hindlimb motor function at 7 days, 14 days, 21 days, and 28 days after SCI. ESCS also significantly increased the myelinated area at 28 days, and reduced the number of apoptotic cells in the spinal white matter at 7 days. SCI decreased the expression of 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase, an oligodendrocyte marker) at 7 days and that of myelin basic protein at 28 days. ESCS significantly upregulated these markers and increased the percentage of Sox2/CNPase/DAPI-positive cells (newly differentiated oligodendrocytes) at 7 days. Recombinant human bone morphogenetic protein 4 (rhBMP4) markedly downregulated these factors after ESCS. Furthermore, ESCS significantly decreased BMP4 and p-Smad1/5/9 expression after SCI, and rhBMP4 reduced this effect of ESCS. These findings indicate that ESCS enhances the survival and differentiation of oligodendrocytes, protects myelin, and promotes motor functional recovery by inhibiting the BMP4-Smad1/5/9 signaling pathway after SCI.

Transforaminal Versus Lateral Parasagittal Versus Midline Interlaminar Lumbar Epidural Steroid Injection for Management of Unilateral Radicular Lumbar Pain: A Randomized Double-Blind Trial

BACKGROUND

Epidural steroid injections (ESIs) are commonly used for management of lumbosacral radicular pain. Midline interlaminar (MIL) or transforaminal (TF) routes are commonly used. The TF route, although associated with higher delivery of drug to the ventral epidural space, has serious complications including spinal cord injury and permanent paralysis reported in literature. Therefore, there is a search for a technically better route with fewer complications and greater drug delivery into the ventral epidural space. Recently, a parasagittal interlaminar (PIL) approach has been defined.

OBJECTIVES

We conducted this study to compare therapeutic effectiveness of 3 techniques of ESIs in patients having unilateral lumbar radiculopathy. Further, effect of ESI on bone mineral density (BMD) and serum osteocalcin levels were studied.

STUDY DESIGN

Randomized double-blind trial.

SETTING

Pain clinic of a tertiary care hospital.

METHODS

Sixty-five patients were randomly allocated into group MIL, group PIL, and group TF to receive epidural injection with 80 mg of methylprednisolone and 2 mL of 2% lidocaine. Effective pain relief and improvement in disability were assessed using Visual Analog Scale (VAS) and Modified Oswestry Disability Questionnaire (MODQ) scores at 2 weeks, 4 weeks, 3 months, and 6 months, respectively. Patients with < 50% relief received additional injection. Primary outcome of study was effective pain relief at 6 months. Mean change in VAS and MODQ scores, BMD, and serum osteocalcin levels were secondary outcome assessed.

RESULTS

Patients having effective pain relief were significantly higher in group PIL (16 of 20 [80%]) and group TF (15 of 20 [75%]) compared with group MIL. Patients receiving ESI in group PIL and group TF showed significantly lower VAS scores than group MIL (P = 0.02, P = 0.50 at 3 months and P = 0.00, P = 0.02 at 6 months, respectively). Mean MODQ scores in group PIL and group TF were significantly lower than group MIL. However, group PIL and group TF did not significantly differ in MODQ scores. There was no significant change in serum osteocalcin and BMD, as assessed by dual energy x-ray absorptiometry scan at 3 months.

LIMITATIONS

The absence of a placebo control group, small sample size, and relatively short follow-up of 6 months were limitations.

CONCLUSIONS

PIL approach is equivalent to TF and superior to MIL approach in terms of effective pain relief and decrease in disability in patients with unilateral lumbar radiculopathy. This study showed no deleterious effect on BMD.

KEY WORDS

Epidural steroid, technique, efficacy, bone marrow density, serum osteocalcin.

Applying Multichannel Optogenetic System for Epidural Spinal Cord Stimulation in Rats

This study reports on the technique of applying multichannel optogenetic system to spinal cord stimulation in rats. Epidural spinal cord stimulation has been shown to reactivate spinalized hind limb motion; however, the stimulating parameters and detailed mechanism remain unclear. In order to utilize the high spatial resolution and cell type selectivity of optogenetics for studying the mechanism behind epidural spinal cord stimulation, a multichannel optical fiber bundle was designed, composed of 720 optical fibers of 200 $\mu $m diameter arranged in a 48$\times $ textbf15 matrix cover the vertebral columns of rats from level T13 to L2. The stimulating location was controlled by changing the direction of projection of a laser diode, and the appropriate projecting angle to obtain the maximum optical power output of each fiber was determined by a hill-climbing algorithm. A spinal cord window was developed to fit the head of the optical fiber bundle onto the dorsal part of rat spinal cord. Preliminary test in a rat revealed different stimulating area distribution of the optogenetically induced tibialis anterior (TA) and medial gastrocnemius (MG) muscle reactions and demonstrated the capability of the system for in-vivo study.

Long-term functionality of a soft electrode array for epidural spinal cord stimulation in a minipig model

Long-term biointegration of man-made neural interfaces is influenced by the mechanical properties of the implant materials. Substantial experimental work currently aims at replacing conventional hard implant materials with soft alternatives that can favour a lower immune response. Here we assess the performance of a soft electrode array implanted in the spinal epidural space of a minipig model for a period of 6 months. The electrode array includes platinum-silicone electrode contacts and elastic thin-film gold interconnects embedded in silicone. textbfIn-vivo electrode impedance and voltage transients were monitored over time. Following implantation, epidural stimulation produced muscle-specific evoked potentials and visible muscle contractions. Over time, postoperative and stimulation induced changes in electrode impedance were observed. Such trends provide a basis for future technological improvements aiming at ensuring the stability of soft implantable electrodes for neural interfacing.

In Vitro Biomechanical Study of Epidural Pressure during the Z-shape Elevating-Pulling Reduction Technique for Cervical Unilateral Locked Facets

Objective: To analyze the mechanism of the halo vest-assisted Z-shape elevating-pulling reduction technique for cervical unilateral locked facets, and confirm the safety of the spinal cord under the epidural pressure that occurs during the reduction process. Methods: Eleven osteoligamentous whole coronal and cervical spine specimens were established as skull-neck-thorax models of cervical unilateral locked facets at the C5/6 level. The halo vest-assisted Z-shape elevating-pulling reduction technique was then applied to reduce the locked facets. The changes in the epidural pressure in five cervical positions (cervical physiological curvature, cervical lateral bending, cervical unilateral locked facets, cervical unilateral perched facets, and reduction) were measured by a pressure sensor during the reduction procedure. The models simultaneously underwent multi-angle radiographic examination and CT scanning. Results: Successful closed reduction was achieved via the halo vest-assisted Z-shape elevating-pulling reduction technique in all 11 models. The epidural pressure in the cervical unilateral locked facets position was significantly higher than that in the other four cervical positions (P < 0.005). There was no significant difference in the epidural pressures measured during cervical lateral bending, cervical unilateral perched facets, and reduction. Conclusions: Maximum epidural pressures were measured in the position of cervical unilateral locked facets. The halo vest-assisted Z-shape elevating-pulling reduction technique achieved spinal decompression without causing secondary spinal cord injury. The halo vest-assisted Z-shape elevating-pulling reduction technique is safe and effective, and has a high success rate of reduction.