Brain fMRI during orientation selective epidural spinal cord stimulation.

Epidural spinal cord stimulation (ESCS) is widely used for chronic pain treatment, and is also a promising tool for restoring motor function after spinal cord injury. Despite significant positive impact of ESCS, currently available protocols provide limited specificity and efficiency partially due to the limited number of contacts of the leads and to the limited flexibility to vary the spatial distribution of the stimulation field in respect to the spinal cord. Recently, we introduced Orientation Selective (OS) stimulation strategies for deep brain stimulation, and demonstrated their selectivity in rats using functional MRI (fMRI). The method achieves orientation selectivity by controlling the main direction of the electric field gradients using individually driven channels. Here, we introduced a similar OS approach for ESCS, and demonstrated orientation dependent brain activations as detected by brain fMRI. The fMRI activation patterns during spinal cord stimulation demonstrated the complexity of brain networks stimulated by OS-ESCS paradigms, involving brain areas responsible for the transmission of the motor and sensory information. The OS approach may allow targeting ESCS to spinal fibers of different orientations, ultimately making stimulation less dependent on the precision of the electrode implantation.

Safety Evaluation of Biportal Endoscopic Lumbar Discectomy: Assessment of Cervical Epidural Pressure During Surgery.

STUDY DESIGN: A prospective study. OBJECTIVE: To evaluate the change in cervical epidural pressure (CEP) during biportal endoscopic lumbar discectomy (BELD). SUMMARY OF BACKGROUND DATA: In percutaneous uniportal endoscopic lumbar discectomy, irrigation fluid (IF) introduced into the spinal canal during surgery can compress the thecal sac, and act as a potential risk for neurological complications by disturbing cerebrospinal fluid (CSF) circulation and increasing intracranial pressure. METHODS: Thirty consecutive patients, who underwent BELD, which was performed under automated pump system, an infusion pressure of 30 mmHg were enrolled. The change in CEP on C7-T1 level was measured. CEP was measured in each of the five phases of the procedure (1st phase-making surgical portals; 2nd phase-creating a workspace; 3rd phase-performing neural decompression and discectomy; 4th phase-factitious increase of pressure by clogging the outflow; 5th phase-dismission from fluid irrigation system). Neurological complications and independent risk factors were evaluated. RESULTS: In the final 27 patients, changes in CEP during surgery were similar. The baseline CEP was 14.8 ±â€Š2.8 mmHg, and the mean CEP in the 3rd phase 18.8 ±â€Š5.1 mmHg was not significantly higher. In the 4th phase, however, the CEPs rose with linear correlation as the pressure increased. In the 5th phase, the elevated CEP returned to baseline in 2.5 ±â€Š5.6 minutes. No patient had neurological complications. No statistically significant risk factors were observed. CONCLUSION: In BELD, which is performed to allow continuous lavage with infusion pressure set to 30 mmHg, CEP does not increase beyond the physiological range. Therefore, BELD may be considered as a potentially safe technique. LEVEL OF EVIDENCE: 4.

Epidural stimulation for cardiovascular function increases lower limb lean mass in individuals with chronic motor complete spinal cord injury.

NEW FINDINGS: What is the central question of this study? Spinal cord injury results in paralysis and deleterious neuromuscular and autonomic adaptations. Lumbosacral epidural stimulation can modulate motor and/or autonomic functions. Does long-term epidural stimulation for normalizing cardiovascular function affect leg muscle properties? What is the main finding and its importance? Leg lean mass increased after long-term epidural stimulation for cardiovascular function, which was applied in the sitting position and did not activate the leg muscles. Leg muscle strength and fatigue resistance, assessed in a subgroup of individuals, also increased. These adaptations might support interventions for motor recovery and warrant further mechanistic investigation. ABSTRACT: Chronic motor complete spinal cord injury (SCI) results in paralysis and deleterious neuromuscular and autonomic adaptations. Paralysed muscles demonstrate atrophy, loss of force and increased fatigability. Also, SCI-induced autonomic impairment results in persistently low resting blood pressure and heart rate, among other features. We previously reported that spinal cord epidural stimulation (scES) optimized for cardiovascular (CV) function (CV-scES), which is applied in sitting position and does not activate the leg muscles, can maintain systolic blood pressure within a normotensive range during quiet sitting and during orthostatic stress. In the present study, dual-energy X-ray absorptiometry collected from six individuals with chronic clinically motor complete SCI demonstrated that 88 ± 11 sessions of CV-scES (7 days week-1 ; 2 h day-1 in four individuals and 5 h day-1 in two individuals) over a period of ∼6 months significantly increased lower limb lean mass (by 0.67 ± 0.39 kg or 9.4 ± 8.1%; P < 0.001). Additionally, muscle strength and fatigability data elicited by neuromuscular electrical stimulation in three of these individuals demonstrated a general increase (57 ± 117%) in maximal torque output (between 2 and 44 N m in 14 of the 17 muscle groups tested overall) and torque-time integral during intermittent, fatiguing contractions (63 ± 71%; between 7 and 230% in 16 of the 17 muscle groups tested overall). In contrast, whole-body mass and composition did not change significantly. In conclusion, long-term use of CV-scES can have a significant impact on lower limb muscle properties after chronic motor complete SCI.

Topically Applied Cross-Linked Hyaluronan Attenuates the Formation of Spinal Epidural Fibrosis in a Swine Model of Laminectomy.

Epidural fibrosis is an inevitable aspect of the postoperative healing process which is one of the causes of failed back surgery syndrome following spinal surgery. The aim of the present study was to examine the inhibitory effect of 1,4-butanediol diglycidyl ether-crosslinked hyaluronan (cHA) on spinal epidural fibrosis in a swine model. Epidural fibrosis was induced through conduction of hemi-laminotomy (L2 and L3) or laminectomy (L4 and L5), while L1 was assigned as the control group in six pigs. The cHA was applied to L3 and L5 surgical sites. MRI evaluation, histologic examination, expressions of matrix metalloproteinases (MMPs), and cytokines in scar tissue were assessed four months after surgery. cHA treatment significantly decreased the scar formation in both hemi-laminotomy and laminectomy sites. cHA also significantly increased MMP-3 and MMP-9 expression in scar tissue. Further, the epithelial-mesenchymal transition -related factors (transforming growth factor-ß and vimentin) were suppressed and the anti-inflammatory cytokines (CD44 and interleukin-6) were increasingly expressed in cHA-treated sites. The current study demonstrated that cHA may attenuate spinal epidural fibrosis formation after laminectomy surgery by enhancing the expression of MMPs and anti-inflammatory pathways.

Epidural stimulation with locomotor training improves body composition in individuals with cervical or upper thoracic motor complete spinal cord injury: A series of case studies.

CONTEXT: Four individuals with motor complete SCI with an implanted epidural stimulator who were enrolled in another study were assessed for cardiovascular fitness, metabolic function and body composition at four time points before, during, and after task specific training. Following 80 locomotor training sessions, a 16-electrode array was surgically placed on the dura (L1-S1 cord segments) to allow for electrical stimulation. After implantation individuals received 160 sessions of task specific training with epidural stimulation (stand and step). OUTCOME MEASURES: Dual-energy X-ray absorptiometry (DXA), resting metabolic rate and peak oxygen consumption (VO2peak) were measured before locomotor training, after locomotor training but before epidural stimulator implant, at mid-locomotor training with spinal cord epidural stimulation (scES) and after locomotor training with scES. FINDINGS: Participants showed increases in lean body mass with decreases on percentage of body fat, particularly android body fat, and android/gynoid ratio from baseline to post training; resting metabolic rate and VO2peak also show increases that are of clinical relevance in this population. CONCLUSIONS: Task specific training combined with epidural stimulation has the potential to show improvements in cardiovascular fitness and body composition in individuals with cervical or upper thoracic motor complete SCI.

Lumbar epidural lipomatosis is associated with visceral fat and metabolic disorders.

PURPOSE: Lumbar spinal epidural lipomatosis (LEL) is a condition characterized by excessive deposition of epidural fat in the spinal canal. Metabolic abnormalities may be associated with LEL, but few validated reports exist. Thus, we investigated the association between LEL and metabolic disorders in this study. METHODS: A total of 218 patients who had neurological symptoms due to neural compression in the lumbar spinal canal were examined by magnetic resonance imaging (MRI), abdominal computed tomography (CT) scans and blood tests. We evaluated the epidural fat, dural sac and spinal canal areas using MRI, and the visceral fat and subcutaneous fat areas using abdominal CT. We compared the patients' demographics and the radiological parameters between the LEL and non-LEL patients. RESULTS: There were 58 LEL patients and 160 non-LEL patients. The LEL group included more men than women. In the MRI measurement, the dural sac area was similar between the LEL and non-LEL patients; however, the epidural fat/spinal canal ratio was much greater in the LEL group. In the LEL patients, factors associated with metabolic disorders, such as visceral fat area, uric acid (UA) and insulin levels, were significantly greater, compared to the non-LEL patients. In the logistic regression analysis, UA and visceral fat area were the independent explanatory factors in the pathogenesis of LEL. CONCLUSIONS: LEL patients had significantly more visceral fat and increased levels of insulin, UA and ferritin, which are closely related with metabolic disorders. This study indicates that the increased epidural fat in the spinal canal seen in the LEL patients is associated with metabolic syndrome. These slides can be retrieved under Electronic Supplementary material.

A novel approach for automatic visualization and activation detection of evoked potentials induced by epidural spinal cord stimulation in individuals with spinal cord injury.

Voluntary movements and the standing of spinal cord injured patients have been facilitated using lumbosacral spinal cord epidural stimulation (scES). Identifying the appropriate stimulation parameters (intensity, frequency and anode/cathode assignment) is an arduous task and requires extensive mapping of the spinal cord using evoked potentials. Effective visualization and detection of muscle evoked potentials induced by scES from the recorded electromyography (EMG) signals is critical to identify the optimal configurations and the effects of specific scES parameters on muscle activation. The purpose of this work was to develop a novel approach to automatically detect the occurrence of evoked potentials, quantify the attributes of the signal and visualize the effects across a high number of scES parameters. This new method is designed to automate the current process for performing this task, which has been accomplished manually by data analysts through observation of raw EMG signals, a process that is laborious and time-consuming as well as prone to human errors. The proposed method provides a fast and accurate five-step algorithms framework for activation detection and visualization of the results including: conversion of the EMG signal into its 2-D representation by overlaying the located signal building blocks; de-noising the 2-D image by applying the Generalized Gaussian Markov Random Field technique; detection of the occurrence of evoked potentials using a statistically optimal decision method through the comparison of the probability density functions of each segment to the background noise utilizing log-likelihood ratio; feature extraction of detected motor units such as peak-to-peak amplitude, latency, integrated EMG and Min-max time intervals; and finally visualization of the outputs as Colormap images. In comparing the automatic method vs. manual detection on 700 EMG signals from five individuals, the new approach decreased the processing time from several hours to less than 15 seconds for each set of data, and demonstrated an average accuracy of 98.28% based on the combined false positive and false negative error rates. The sensitivity of this method to the signal-to-noise ratio (SNR) was tested using simulated EMG signals and compared to two existing methods, where the novel technique showed much lower sensitivity to the SNR.

Caudal Epidural Block: An Updated Review of Anatomy and Techniques.

Caudal epidural block is a commonly used technique for surgical anesthesia in children and chronic pain management in adults. It is performed by inserting a needle through the sacral hiatus to gain entrance into the sacral epidural space. Using conventional blind technique, the failure rate of caudal epidural block in adults is high even in experienced hands. This high failure rate could be attributed to anatomic variations that make locating sacral hiatus difficult. With the advent of fluoroscopy and ultrasound in guiding needle placement, the success rate of caudal epidural block has been markedly improved. Although fluoroscopy is still considered the gold standard when performing caudal epidural injection, ultrasonography has been demonstrated to be highly effective in accurately guiding the needle entering the caudal epidural space and produce comparative treatment outcome as fluoroscopy. Except intravascular and intrathecal injection, ultrasonography could be as effective as fluoroscopy in preventing complications during caudal epidural injection. The relevant anatomy and techniques in performing the caudal epidural block will be briefly reviewed in this article.

Epidural Spinal Stimulation to Improve Bladder, Bowel, and Sexual Function in Individuals With Spinal Cord Injuries: A Framework for Clinical Research.

While some recent studies that apply epidural spinal cord stimulation (SCS) have demonstrated a breakthrough in improvement of the health and quality of the life of persons with spinal cord injury (SCI), the numbers of people who have received SCS are small. This is in sharp contrast to the thousands of persons worldwide living with SCI who have no practical recourse or hope of recovery of lost functions. Thus, the vision is to understand the full potential of this new intervention and to determine if it is safe and effective in a larger cohort, and if it is scalable so that it can be made available to all those who might benefit. To achieve this vision, the National Institute of Biomedical Imaging and Bioengineering called for and organized a consortium of multiple stakeholder groups: foundations addressing paralysis, federal and public agencies, industrial partners, academicians, and researchers, all interested in the same goal. Based on input from consortium participants, we have reasoned that a first step is to define a scalable SCS approach that is effective in restoring lost autonomic physiology, specifically bladder, bowel, and sexual function. These functions are most critical for improving the quality of life of persons living with SCI. This report outlines a framework for conducting the research needed to define such an effective SCS procedure that might seek Food and Drug Administration approval and be implemented at the population level.

Prevalence of thoracic spine lesions masquerading as cauda equina syndrome: yield of a novel magnetic resonance imaging protocol.

Our objective was to describe the yield of actionable thoracic spine lesions for a novel magnetic resonance imaging (MRI) protocol including evaluation of the thoracic spine among patients presenting to the Emergency Department (ED) with symptoms consistent with epidural compression syndrome. Our ED and Department of Radiology together designed a novel rapid MRI protocol entailing 3D volumetric T2 weighted sequences through both the thoracic and lumbar spine obtained in the sagittal plane to assess for both lumbar and thoracic spine lesions. We recorded study outcomes for all patients undergoing this protocol or conventional lumbar MRI during May 2014-May 2015 to determine the prevalence of actionable thoracic spine lesions. We defined an actionable thoracic lesion as any pathology requiring treatment (e.g., medication, admission, surgery) not otherwise indicated on the basis of lumbar spine findings. During the study period, 112 of 124 (90.3%) of ED patients undergoing MRI evaluation for epidural compression syndrome underwent the novel protocol. The remaining patients underwent evaluation of the lumbar spine using only a conventional MRI protocol. Of the 112 patients undergoing the novel protocol, 6 (5.4%) patients had thoracic spine lesions indicating therapy not otherwise indicated by lumbar spine findings. The etiologies of these six lesions were: neoplasms (2), de-myelination (2), compression fracture (1), and degeneration due to pernicious anemia (1). Emergency providers should strongly consider the routine use of MRI protocols including thoracic spine evaluation in patients presenting to the ED with symptoms consistent with epidural compression syndrome.

Epidural and transcutaneous spinal electrical stimulation for restoration of movement after incomplete and complete spinal cord injury.

PURPOSE OF REVIEW: The Purpose of this review is to outline and explain the therapeutic use of electrical spinal cord stimulation (SCS) for modification of spinal motor output. Central functional stimulation provides afferent input to posterior root neurons and is applied to improve volitional movements, posture and their endurance, control spasticity, and improve bladder function or perfusion in the lower limbs. Clinical accomplishments strongly depend on each individual's physiological state and specific methodical adaptation to that physiological state. RECENT FINDINGS: Effectiveness of this neuromodulory technique for changing motor control after spinal cord injury (SCI) continues to be explored along with the underlying mechanisms of its effect in people with complete and incomplete spinal cord injuries. There are extensive studies of tonic and rhythmical activity elicited from the lumbar cord as well as data demonstrating augmentation of residual volitional activity. Recent studies have focused on verifying if and how SCS can modify features of neurocontrol in ambulatory spinal cord patients. SUMMARY: In this review, we emphasize recent publications of research revealing that SCS can substitute for the reduced brain drive for control of excitability in people with SCI. Artificially replacing diminished or lost brain control over the spinal cord has limitations. A fundamental requirement for successful SCS application is analysis of each individual's residual postinjury neural function. This will allow a better understanding of the physiological interactions between SCS and spinal cord motor control below injury and provide criteria for its application. Finally, the publication of both successful and failed applications of SCS will be crucial for gaining future progress.

Radiofrequency Ablation: Temperature Distribution in Adjacent Tissues.

PURPOSE: This clinical study investigates the use of a radiofrequency ablation system specifically developed for the ablation of spinal metastases. The investigation examines possible temperature-associated risks for the adjacent tissues. MATERIAL AND METHODS: A tumour model was simulated for 8 lumbar and 8 thoracic vertebrae of a human cadaveric spine. The tumour mass was ablated with the SpineSTAR electrode (SpineSTAR, DFINE Inc., CA), which has been specifically developed for the ablation of spinal metastases. During the ablation procedure, the temperatures of the vertebra, the epidural space, and the neural foramen were measured with thermocouples. These temperatures were documented as means with standard deviations. Possible differences between lumbar and thoracic vertebrae were analysed with the Mann-Whitney U test. RESULTS: The maximal temperature of the lumbar vertebrae was 46.4 ± 3.3 °C near to the ablation zone, the temperature of the neural foramen was 37.0 ± 0 °C, and the temperature of the epidural space was 37.3 ± 0.7 °C. In the thoracic vertebrae, the temperature was 44.4 ± 1.7 °C near to the ablation zone, 7.9 ± 1.7 °C in the neural foramen, and 37.25 ± 0.7 °C in the epidural space. There was no significant difference in temperature distribution between treated lumbar and thoracic vertebrae. CONCLUSION: Ablation of spinal metastases in a cadaveric model using the SpineSTAR electrode was shown to be a safe method with respect to possible temperature-related risks for the adjacent tissues.

Spinal epidural cavernous angioma: two case reports and review of the literature.

Cavernous angiomas are vascular malformations that occur most frequently in the supratentorial area of the central nervous system (CNS). Spinal epidural occurrence is rare. This article describes 2 cases of spinal epidural cavernous angioma. The lesions were hypo- to isointense on T1-weighted magnetic resonance images (MRIs) and hyperintense on T2-weighted images. Both were enhanced homogenously with intravenous contrast. Total resection was achieved in both cases, and the lesions were histopathologically diagnosed as cavernous angiomas. The patients' symptoms regressed postsurgery. Although the MRI features of cavernous angiomas are well known, spinal epidural occurrence is rare and many differential diagnoses have similar clinical and imaging findings. It is important to definitively diagnose these lesions prior to surgery in order to prevent possible intraoperative complications such as massive bleeding and to maximize chances for complete resection. In addition to case descriptions, this article includes a thorough literature review to raise clinical awareness about this well-known but rare spinal entity.

Neuroprotective effect of epidural hypothermia after spinal cord lesion in rats.

OBJECTIVES: To evaluate the neuroprotective effect of epidural hypothermia in rats subjected to experimental spinal cord lesion. METHODS: Wistar rats (n = 30) weighing 320-360 g were randomized to two groups (hypothermia and control) of 15 rats per group. A spinal cord lesion was induced by the standardized drop of a 10-g weight from a height of 2.5 cm, using the New York University Impactor, after laminectomy at the T9-10 level. Rats in the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed for six weeks using the Basso, Beattie and Bresnahan motor scores and the inclined plane test. At the end of the final week, the rats' neurological status was monitored by the motor evoked potential test and the results for the two groups were compared. RESULTS: Analysis of the Basso, Beattie and Bresnahan scores obtained during the six-week period indicated that there were no significant differences between the two groups. There was no significant difference between the groups in the inclined plane test scores during the six-week period. Furthermore, at the end of the study, the latency and amplitude values of the motor evoked potential test were not significantly different between the two groups. CONCLUSION: Hypothermia did not produce a neuroprotective effect when applied at the injury level and in the epidural space immediately after induction of a spinal cord contusion in Wistar rats.

Neuroprotective effect of epidural hypothermia after spinal cord lesion in rats

OBJECTIVES : To evaluate the neuroprotective effect of epidural hypothermia in rats subjected to experimental spinal cord lesion. METHODS: Wistar rats (n = 30) weighing 320-360 g were randomized to two groups (hypothermia and control) of 15 rats per group. A spinal cord lesion was induced by the standardized drop of a 10-g weight from a height of 2.5 cm, using the New York University Impactor, after laminectomy at the T9-10 level. Rats in the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed for six weeks using the Basso, Beattie and Bresnahan motor scores and the inclined plane test. At the end of the final week, the rats' neurological status was monitored by the motor evoked potential test and the results for the two groups were compared. RESULTS: Analysis of the Basso, Beattie and Bresnahan scores obtained during the six-week period indicated that there were no significant differences between the two groups. There was no significant difference between the groups in the inclined plane test scores during the six-week period. Furthermore, at the end of the study, the latency and amplitude values of the motor evoked potential test were not significantly different between the two groups. CONCLUSION: Hypothermia did not produce a neuroprotective effect when applied at the injury level and in the epidural space immediately after induction of a spinal cord contusion in Wistar rats. .

All-trans retinoic acid prevents epidural fibrosis through NF-κB signaling pathway in post-laminectomy rats.

Laminectomy is a widely accepted treatment for lumbar disorders, and epidural fibrosis (EF) is a common complication. EF is thought to cause post-operative pain recurrence after laminectomy or discectomy. All-trans retinoic acid (ATRA) has shown anti-fibrotic, anti-inflammatory, and anti-proliferative functions. The object of this study was to investigate the effects of ATRA on the prevention of EF in post-laminectomy rats. In vitro, the anti-fibrotic effect of ATRA was demonstrated with cultured fibroblasts count, which comprised of those that were cultured with/without ATRA. In vivo, rats underwent laminectomy at the L1-L2 levels. We first demonstrated the beneficial effects using 0.05% ATRA compared to vehicle (control group). We found that a higher concentration of ATRA (0.1%) achieved dose-dependent results. Hydroxyproline content, Rydell score, vimentin-positive cell density, fibroblast density, inflammatory cell density and inflammatory factor expression levels all suggested better outcomes in the 0.1% ATRA rats compared to the other three groups. Presumably, these effects involved ATRA's ability to suppress transforming growth factor (TGF-ß1) and interleukin (IL)-6 which was confirmed with reverse-transcriptase polymerase chain reaction (RT-PCR). Finally we demonstrated that ATRA down-regulated nuclear factor (NF)-κB by immunohistochemistry and western blotting for p65 and inhibition of κB (IκBα), respectively. Our findings indicate that topical application of ATRA can inhibit fibroblast proliferation, decrease TGF-ß1 and IL-6 expression level, and prevent epidural scar adhesion in rats. The highest concentration employed in this study (0.1%) was the most effective. ATRA suppressed EF through down-regulating NF-κB signaling, whose specific mechanism is suppression of IκB phosphorylation and proteolytic degradation.

Update on intracranial hypertension and hypotension.

PURPOSE OF REVIEW: The aim of this article is to review recent findings on the pathophysiology of idiopathic changes in intracranial pressure. The review will focus on idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH). RECENT FINDINGS: Substantial evidence indicates that IIH is associated with delayed absorption of cerebrospinal fluid (CSF). Stenoses of the transverse sinus are common in IIH, but their clinical significance has not been entirely clarified. Despite the observed efficacy of endovascular treatment in some IIH patients, a correlation between the extent of observed stenoses and the clinical course of the disease could not be demonstrated. The underlying cause of SIH is a spontaneous CSF leakage into the epidural space. Conservative treatment and the epidural blood patch remain the treatment of choice for this rare syndrome. SUMMARY: Recent clinical evidence indicates that IIH is probably a result of CSF outflow abnormality rather than of CSF production. Further research is needed to elucidate the causes of elevated intracranial pressure and the mechanism leading to visual loss. Prospective randomized clinical trials are needed to clarify a possible therapeutic potential of endovascular treatment. Research efforts on SIH should focus further on associated connective tissue disorders predisposing to CSF leaks.

Efficacy of hemostasis for epidural venous plexus and safety for neural structure using soft coagulation system in spinal surgery: a laboratory investigation using a porcine model.

STUDY DESIGN: A laboratory investigation using porcine model. OBJECTIVE: To clarify the effectiveness of the soft coagulation system for stopping bleeding from the epidural vein using different outputs and the safety in terms of tissue damage including spinal cord injury. SUMMARY OF BACKGROUND DATA: Problems associated with coagulation using an electrosurgical device, such as carbonization of tissue or adhesion to the electrode, have been highlighted. So called "soft coagulation" has been developed to solve these problems. Its' utility as well as the safety of the neural structure in spine surgery has never been reported. METHODS: A total of 3 animals and 45 spinal segments were used. Total laminectomy was performed to expose the dural tube and epidural venous plexus. Stable bleeding was induced by a 22 G needle puncture. Soft coagulation monopolar output (SCM), soft coagulation bipolar output (SCB), and conventional bipolar output (CB) were used as the coagulators. Valid hemostasis was defined as macroscopically complete bleeding stoppage by coagulation within 3 minutes. The neurological assessment was evaluated by somatosensory evoked potential. Histologic analysis was performed to determine the area of thermal damage. RESULTS: Valid hemostasis ratio was 75.0% of SCM group, 68.8% of SCB group, and 30.8% of CB group. Somatosensory evoked potential monitoring revealed that spinal cord injury was observed in 4 lesions (25%) of the SCM group. Neither bipolar groups (SCB and CB) showed any changes in waveform pattern. Histologic analysis revealed that severe thermal damages were observed in the epidural space of the SCM group. CONCLUSIONS: The usefulness of soft coagulation is revealed in terms of bleeding stoppage from epidural vessels and reduced soft-tissue damage compared with the conventional electric device. However, assessing the potential risk of severe neural tissue damage including spinal cord injury, a bipolar soft coagulation is strongly recommended for use in spine surgery.

Spontaneous resolution of a thoracic spinal epidural arteriovenous fistula caused by stabbing injury.

STUDY DESIGN: A single case is presented of a spontaneously resolving epidural arteriovenous fistula caused by a stab wound. OBJECTIVE: To demonstrate a unique case of a spontaneously resolving epidural arteriovenous fistula caused by a stab wound, as well as to present a brief review of pathology. SUMMARY OF BACKGROUND DATA: Spinal epidural arteriovenous fistulas (SEAVF) are high-flow vascular malformations characterized by an arteriovenous shunt involving the internal vertebral venous plexus (IVVP). SEAVFs can present with intramedullary, subarachnoid or epidural hemorrhages, spinal cord or nerve root compression, and progressive myelopathy secondary to medullary venous hypertension. The type of venous drainage (intradural, extradural, or mixed) strongly influences the mode of presentation. Spontaneous resolution of a spinal vascular malformation is a well-documented yet rare phenomenon. METHODS: Angiographical and magnetic resonance images of the lesion were obtained pre- and post spontaneous resolution. A brief review of the topic is also presented. RESULTS: Our observation identifies stabbing as an unusual mechanism for the formation of a SEAVF, and offers an angiographically documented example of complete spontaneous resolution of this type of vascular malformation. SEAVFs of traumatic origin have been previously reported, but we believe that our observation represents the first documentation of such a lesion being caused by stabbing with subsequent spontaneous resolution. CONCLUSION: Spinal epidural arteriovenous fistulas (SEAVFs) are increasingly diagnosed vascular malformations with the potential to inflict serious neurological damage if not recognized and treated in time. Spontaneous resolution of a spinal vascular malformation is a well-documented yet rare phenomenon. Our observation identifies stabbing as an unusual mechanism for the formation of a SEAVF, and offers an example of complete spontaneous resolution of this type of vascular malformation.

Controlled unilateral isometric force generated by epidural spinal cord stimulation in the rat hindlimb.

Epidural electrical stimulation (EES) has often been used to restore stereotypic locomotor movements after spinal cord injury (SCI). However, restoring freeform movement requires specific force generation and independently controlled limbs for changing environments. Therefore, a second stimulus location would be advantageous, controlling force separately from locomotor movements. In normal and transected rats treated with mineral oil or saline, EES was performed at L1-L6 vertebral levels, caudal to spinal segments typical for locomotion, identifying secondary sites capable of activating hindlimb musculature, producing unilateral force at the paw. Threshold for generating force was identified and stimulation amplitude and duration varied to assess effects on evoked forces. Stimulation at L2 and L3 vertebral levels elicited negative vertical forces from extensor musculature while stimulation at L4 and L5 elicited positive vertical forces from flexion musculature. Thresholds were unchanged with transection or hydration method. Peak force magnitude was significantly correlated to stimulus amplitude, and response duration significantly correlated to stimulus duration in all animals. No differences were found in correlation coefficients or slopes of the regression for force or duration analyses with spinal condition or hydration method. This model demonstrates the ability to induce controlled forces with EES after SCI.