Biomedical subjects

Michael G Fehlings

Publications and source records attributed to Michael G Fehlings.

At least 19 recordsLinked to original sources

PubMed2006

Hematologic abnormalities within the first week after acute isolated traumatic cervical spinal cord injury: a case-control cohort study.

STUDY DESIGN: Case-control cohort study. OBJECTIVE: To evaluate 1) the hematologic abnormalities within the first week following isolated acute cervical spine trauma or spinal cord injury (SCI); and 2) the influence of age, sex, and severity of SCI on these hematologic abnormalities. SUMMARY OF BACKGROUND DATA: Given that autonomic nervous system has a critical role in the regulation of the hematopoietic system, we sought to evaluate the potential association between hematologic abnormalities within the first week posttrauma and the severity of SCI. METHODS: All consecutive individuals with isolated acute cervical spine trauma admitted to our institution from 1998 to 2000 were reviewed. Exclusion criteria included preexisting medical comorbidities and polytrauma. The study population was divided into a SCI group and a control group (individuals with spine trauma without neurologic impairment). The SCI group was subdivided into patients with motor complete SCI (American Spinal Injury Association [ASIA] Grades A/B) and individuals with motor incomplete SCI (ASIA Grades C/D). RESULTS: There were 21 SCI individuals (15 male, 6 female; ages 17-83 years; mean, 57 years) and 11 controls (6 male, 5 female; ages 18-75 years; mean, 41 years). When controlled for age, SCI individuals showed a significantly higher frequency of reduced hemoglobin concentration (RHC), leukocytosis, lymphopenia, and thrombocytopenia than controls within the first week posttrauma. Blood hemoglobin concentration, lymphocyte, and platelet counts in the SCI group were significant lower than the controls. The SCI group showed a significant higher leukocyte count than the controls. The degree of RHC and lymphopenia was significantly correlated with the severity of SCI. CONCLUSION: Our results indicate that patients with isolated cervical SCI have significantly greater frequency of RHC, leukocytosis, lymphopenia, and thrombocytopenia than controls during the first week posttrauma. The degree of RHC and lymphopenia was significantly associated with the severity of SCI. While the mechanisms underlying these clinically important hematologic consequences of SCI remain undetermined, evidence from the literature suggests that acute autonomic denervation of the hematopoietic system could play a key role.

Adolescent↗

PubMed2006

Multimodality intraoperative neurophysiologic monitoring findings during surgery for adult tethered cord syndrome: analysis of a series of 44 patients with long-term follow-up.

STUDY DESIGN: Prospective analysis of a consecutive series in which multimodality intraoperative neurophysiologic monitoring was used as an adjunct to microneurosurgery for adult tethered cord syndrome. The results of multimodality intraoperative neurophysiologic monitoring were compared with the "gold standard" (neurologic outcomes). OBJECTIVE: To assess the sensitivity, specificity, and positive and negative predictive values of multimodality intraoperative neurophysiologic monitoring in surgery for adult tethered cord syndrome. SUMMARY OF BACKGROUND DATA: Although intraoperative electrophysiologic techniques may help to minimize neural injury during spinal microneurosurgery, to our knowledge, no study has quantitatively evaluated the value of multimodality intraoperative neurophysiologic monitoring in the management of adult tethered cord syndrome. METHODS: Multimodality intraoperative neurophysiologic monitoring included posterior tibial nerve somatosensory evoked potentials (SSEPs), continuous electromyographic (EMG) monitoring of the L2 to S4 myotomes, and evoked EMG. Follow-up neurologic evaluations were performed for at least 1 year. RESULTS: A total of 44 consecutive patients, including 19 males and 25 females (aged 43 +/- 15 years), who underwent microsurgery for adult tethered cord syndrome were evaluated. After surgery, new neurologic deficits, including 1 transient and 1 permanent, developed in 2 patients. There was 1 patient who had persistent posterior tibial nerve SSEP amplitude reduction following microsurgical manipulation. In 1 patient, a transient posterior tibial nerve SSEP amplitude reduction prompted a change in microneurosurgical strategy. This patient awoke with no new postoperative neurologic deficits. For SSEPs, the sensitivity was 50% and specificity 100%. EMG bursts were recorded in 36 patients (82%). The 2 patients with postoperative neurologic worsening had EMG activity in the myotomes, where their new deficits presented. Continuous EMG had a sensitivity of 100% and a specificity of 19%. CONCLUSIONS: To our knowledge, this is the largest series to date reporting the use of multimodality intraoperative neurophysiologic monitoring in the surgical management of adult tethered cord syndrome. Posterior tibial nerve SSEPs have high specificity, but low sensitivity, for predicting new neurologic deficits. In contrast, continuous EMG showed high sensitivity and low specificity. Evoked EMG accurately identified functional neural tissue. The combined recording of SSEPs in concert with continuous and evoked EMGs may provide a useful adjunct to complex microsurgery for adult tethered cord syndrome.

Adult↗

PubMed2006

An ex vivo preparation of mature mice spinal cord to study synaptic transmission on motoneurons.

Mammalian spinal cord motoneurons are highly susceptible to chemical and mechanical disturbances, which imposes substantial difficulties for electrophysiological investigation in acute in vitro preparations. The aim of the present study was to establish an isolated spinal cord preparation from adult mice and to examine the synaptic activities of motoneurons in vitro. We removed the lumbo-sacral cord from the vertebral canal by hydraulic extrusion and maintained the isolated cord in vitro for extracellular recordings. Population spikes of motoneurons were evoked by electrical stimulation of dorsal roots (orthodromic) or ventral roots (antidromic) and these evoked responses could be continuously monitored for 5-6 h. The orthodromic population spikes were reversibly suppressed by the AMPA/kainate receptor antagonist 2,3-dihyro-6-nitro-7-sulfamoylbenzo quinoxaline (NBQX, 10 microM) but they persisted in the presence of the NMDA receptor antagonist D(-)-2-amino-5-phosphonovaleric acid (AP5, 50 microM). The antidromic population spikes exhibited evident paired pulse inhibition when evoked at inter-stimulus intervals of pound 6 ms. Histological examination revealed that basic morphological features of the lumbo-sacral motoneurons were preserved after 3-4 h of in vitro maintenance. This in vitro preparation is ideally suited for the electrophysiological study of synaptic transmission on adult mouse spinal motoneurons.

2-Amino-5-phosphonovalerate↗

PubMed2006

Assessment of injury to the posterior ligamentous complex in thoracolumbar spine trauma.

BACKGROUND CONTEXT: Posterior ligamentous complex (PLC), consisting of supraspinous ligament (SSL), interspinous ligament (ISL), ligamentum flavum (LF), and the facet joint capsules is thought to contribute significantly to the stability of thoracolumbar spine. Currently, no consensus exists on radiographic imaging parameters that may indicate injury to the posterior ligamentous complex. PURPOSE: To identify imaging parameters that may suggest a disruption of the PLC of the thoracolumbar spine. STUDY DESIGN/SETTING: A survey analysis of members of the Spine Trauma Study Group. PATIENT SAMPLE: None. OUTCOMES MEASURES: Compilation of survey results. METHODS: An extensive review of the literature from 1949 to the present was performed to identify key radiographic elements that have been suggested as indicators of PLC injury. Twelve items identified as such were placed on a survey and sent to the members of the Spine Trauma Study Group. They were asked to rank the items from most important to least important, and the results were compiled for analysis. RESULTS: Twenty-eight surveys were returned for final analysis. Fifty-percent (14/28) of the members ranked "vertebral body translation" on plain radiographs as the most important factor in determining disruption of PLC. Plain radiographic signs were ranked higher than computed tomography or magnetic resonance imaging indicators, and history of the mechanism ranked lowest. The members were also given freedom to add other criteria that they felt were important in determining PLC integrity. "Interspinous spacing 7 mm greater than that of level above or below on antero posterior plain X-rays" was the only new category that was suggested. CONCLUSION: Plain radiographic findings were felt to be most helpful in determining PLC injury by the members of the Spine Trauma Study Group. Physical examination findings and history of the mechanism of injury were ranked lower than imaging studies. Future analysis should focus on indicators of PLC injury when plain radiographic findings are either subtle or not present.

Consensus↗

PubMed2006

Interobserver and intraobserver reliability of maximum canal compromise and spinal cord compression for evaluation of acute traumatic cervical spinal cord injury.

STUDY DESIGN: Prospective, blinded validation study of an objective, quantitative measure to assess maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) in individuals with acute cervical spinal cord injury (SCI). OBJECTIVE: To examine the intraobserver and interobserver reliability of MCC and MSCC in individuals with acute traumatic cervical SCI. SUMMARY OF BACKGROUND DATA: To date, few quantitative reliable radiologic methods for assessing the extent of spinal cord compression in the setting of acute SCI have been reported. MCC and MSCC, as assessed on mid-sagittal CT and T2-weighted MR images, respectively, appear to have potential clinical and prognostic value. To date, the validation of these assessment tools has been limited to a small number of observers at a single institution. However, to date no study has focused on the reliability of these radiologic parameters among a large cohort of spine surgeons from North America and abroad. This type of validation is critical to allow the broader use of these outcome measures in research studies and in clinical practice. METHODS: Mid-sagittal MRI and CT images of cervical spine were selected from 10 individuals with acute traumatic cervical SCI. A total of 28 spine surgeons independently estimated CT MCC, T1-weighted MRI MCC, and T2-weighted MRI MSCC on two occasions using a calibrated ruler. In the first round of measurements, the observers estimated the radiologic parameters using only written instructions. The second measurement set was obtained after an interactive teaching session on the methodology. The order of the images was altered for the second set of measurements. RESULTS: Analysis using parametric and nonparametric statistics indicated high intraobserver reliability for CT MCC, T1-weighted MRI MCC, and T2-weighted MSCC with interclass correlation coefficients (ICCs) of 0.92, 0.95, and 0.97, respectively. The interobserver reliability for all three radiologic parameters was considered moderate with ICCs ranging from 0.35 to 0.56. CONCLUSION: Our results indicate that the intraobserver reliability for the MCC and MSCC was high. Although the interobserver reliability for all three radiologic parameters in the present study was below 0.75, the observed differences were small and largely accounted for by the limitations in the precision of the calibrated ruler. For cases with minimal cord compression, the measurement of canal stenosis (MCC) proved more accurate. In contrast, in cases with severe cord compression, the assessment of MSCC was more accurate. It is anticipated that the use of digital imaging technologies will further enhance the precision of these outcome measures.

Acute Disease↗

PubMed2006

Intraoperative adverse events and related postoperative complications in spine surgery: implications for enhancing patient safety founded on evidence-based protocols.

STUDY DESIGN: Prospective observational study. OBJECTIVE: To assess the incidence and clinical consequence of intraoperative adverse events from a wide variety of spinal surgical procedures. SUMMARY OF BACKGROUND DATA: In this study, adverse events were defined as any unexpected or undesirable event(s) occurring as a result of spinal surgery. A complication was defined as a disease or disorder, which, as a consequence of a surgical procedure, will negatively affect the outcome of the patient. We hypothesized that most adverse events would not result in complications that would be normally flagged through traditional practice audit approaches. By defining the incidence and types of adverse events seen in a spine surgical practice, we hope to develop preventative approaches to enhance patient safety. METHODS: All postoperative clinical sequelae (i.e., complications) were prospectively identified, classified as to type, and graded (0 [none] to IV [death]) in 700 consecutive patients who underwent spine surgery (excluding > 300-day surgery microdiscectomies) at a university center from January 2002 to June 2003. To confirm data accuracy and assess the clinical sequelae of any adverse events, the medical records of these 700 patients were reviewed. RESULTS: The overall incidence of intraoperative adverse events was 14% (98/700). A total of 23 adverse events led to postoperative clinical sequelae for an overall intraoperative complication incidence of 3.2% (23/700). Specific adverse events included dural tears (n = 58), spinal instrumentation-related events (n = 12), blood loss exceeding 5000 mL (n = 10), anesthesia/medical (n = 4), suspected or actual vertebral artery injury (n = 3), approach-related events (n = 3), esophageal/pharyngeal injury (n = 2), and miscellaneous (n = 6). CONCLUSIONS: Adverse events can frequently occur (14%) during spinal surgery, however, the majority (76.5%) are not associated with complications. Improved patient safety can only be maximized by independent practice audit and the development of prospective methods to record adverse event data so that enhanced, evidence-based, clinical protocols can be developed.

Clinical Protocols↗

PubMed2006

Ischemic insults direct glutamate receptor subunit 2-lacking AMPA receptors to synaptic sites.

Regulated AMPA receptor (AMPAR) trafficking at excitatory synapses is a mechanism critical to activity-dependent alterations in synaptic efficacy. The role of regulated AMPAR trafficking in insult-induced synaptic remodeling and/or cell death is, however, as yet unclear. Here we show that brief oxygen-glucose deprivation (OGD), an in vitro model of brain ischemia, promotes redistribution of AMPARs at synapses of hippocampal neurons, leading to a switch in AMPAR subunit composition. Ischemic insults promote internalization of glutamate receptor subunit 2 (GluR2)-containing AMPARs from synaptic sites via clathrin-dependent endocytosis and facilitate delivery of GluR2-lacking AMPARs to synaptic sites via soluble N-ethylmaleimide-sensitive factor attachment protein receptor-dependent exocytosis, evident at early times after insult. The OGD-induced switch in receptor subunit composition requires PKC activation, dissociation of GluR2 from AMPA receptor-binding protein, and association with protein interacting with C kinase-1. We further show that AMPARs at synapses of insulted neurons exhibit functional properties of GluR2-lacking AMPARs. AMPAR-mediated miniature EPSCs exhibit increased amplitudes and enhanced sensitivity to subunit-specific blockers of GluR2-lacking AMPARs, evident at 24 h after ischemia. The OGD-induced alterations in synaptic AMPA currents require clathrin-mediated receptor endocytosis and PKC activation. Thus, ischemic insults promote targeting of GluR2-lacking AMPARs to synapses of hippocampal neurons, mechanisms that may be relevant to ischemia-induced synaptic remodeling and/or neuronal death.

Animals↗

PubMed2006

The timing of surgical intervention in the treatment of spinal cord injury: a systematic review of recent clinical evidence.

STUDY DESIGN: Evidence-based literature review. OBJECTIVE: To provide updated evidence-based recommendations regarding spinal cord decompression in patients with acute spinal cord injury (SCI). SUMMARY OF BACKGROUND DATA: It is controversial whether early decompression following SCI conveys a benefit in neurologic outcome. METHODS: MEDLINE search of experimental and clinical studies showing the effect of decompression on neurologic outcome following SCI. We focused on articles published within the last 10 years, with a particular emphasis on research conducted within the past 5 years. RESULTS: A total of 66 articles were retrieved. Animal studies consistently show that neurologic recovery is enhanced by early decompression. There was 1 randomized controlled trial that showed no benefit to early (<72 hours) decompression. Several recent prospective series suggest that early decompression (<72 hours) can be performed safely and may improve neurologic outcomes. A recent systematic review showed that early decompression (<24 hours) resulted in statistically better outcomes compared to both delayed decompression and conservative treatment. CONCLUSIONS: There are currently no standards regarding the role and timing of decompression in acute SCI. We recommend urgent decompression of bilateral locked facets in a patient with incomplete tetraplegia or in a patient with SCI with neurologic deterioration. Urgent decompression in acute cervical SCI remains a reasonable practice option and can be performed safely. There is emerging evidence that surgery within 24 hours may reduce length of intensive care unit stay and reduce post-injury medical complications.

Animals↗

PubMed2006

Delayed transplantation of adult neural precursor cells promotes remyelination and functional neurological recovery after spinal cord injury.

Spinal cord injury (SCI) results in loss of oligodendrocytes demyelination of surviving axons and severe functional impairment. Spontaneous remyelination is limited. Thus, cell replacement therapy is an attractive approach for myelin repair. In this study, we transplanted adult brain-derived neural precursor cells (NPCs) isolated from yellow fluorescent protein-expressing transgenic mice into the injured spinal cord of adult rats at 2 and 8 weeks after injury, which represents the subacute and chronic phases of SCI. A combination of growth factors, the anti-inflammatory drug minocycline, and cyclosporine A immunosuppression was used to enhance the survival of transplanted adult NPCs. Our results show the presence of a substantial number of surviving NPCs in the injured spinal cord up to 10 weeks after transplantation at the subacute stage of SCI. In contrast, cell survival was poor after transplantation into chronic lesions. After subacute transplantation, grafted cells migrated >5 mm rostrally and caudally. The surviving NPCs integrated principally along white-matter tracts and displayed close contact with the host axons and glial cells. Approximately 50% of grafted cells formed either oligodendroglial precursor cells or mature oligodendrocytes. NPC-derived oligodendrocytes expressed myelin basic protein and ensheathed the axons. We also observed that injured rats receiving NPC transplants had improved functional recovery as assessed by the Basso, Beattie, and Bresnahan Locomotor Rating Scale and grid-walk and footprint analyses. Our data provide strong evidence in support of the feasibility of adult NPCs for cell-based remyelination after SCI.

Animals↗

PubMed2006

Radiographic measurement parameters in thoracolumbar fractures: a systematic review and consensus statement of the spine trauma study group.

STUDY DESIGN: Systematic review. OBJECTIVES: To review the various radiographic parameters currently used to assess traumatic thoracolumbar injuries, emphasizing the validity and technique behind each one, to formulate evidence-based guidelines for a standardized radiographic method of assessment of these fractures. SUMMARY OF BACKGROUND DATA: The treatment of thoracolumbar fractures is guided by various radiographic measurement parameters. Unfortunately, for each group of parameters, there has usually been more than 1 proposed measurement technique, thus creating confusion when gathering data and reporting outcomes. Ultimately, this effect results in clinical decisions being based on nonstandardized, nonvalidated outcome measures. METHODS: Computerized bibliographic databases were searched up to January 2004 using key words and Medical Subject Headings on thoracolumbar spine trauma, radiographic parameters, and methodologic terms. Using strict inclusion criteria, 2 independent reviewers conducted study selection, data abstraction, and methodologic quality assessment. RESULTS: There were 18 original articles that ultimately constituted the basis for the review. Of radiographic measurement parameters, 3 major groups were identified, depicting the properties of the injured spinal column: sagittal alignment, vertebral body compression, and spinal canal dimensions, with 14 radiographic parameters reported to assess these properties. CONCLUSIONS: Based on a systematic review of the literature and expert opinion from an experienced group of spine trauma surgeons, it is recommended that the following radiographic parameters should be used routinely to assess thoracolumbar fractures: the Cobb angle, to assess sagittal alignment; vertebral body translation percentage, to express traumatic anterolisthesis; anterior vertebral body compression percentage, to assess vertebral body compression, the sagittal-to-transverse canal diameter ratio, and canal total cross-sectional area (measured or calculated); and the percent canal occlusion, to assess canal dimensions.

Consensus↗

PubMed2006

A Web-based systematic review on traumatic spinal cord injury comparing the "citation classics" with the consumers' perspectives.

Although the citation index of an article is not a direct measure of its quality or importance, it is a measure of recognition that may suggest its impact on the scientific community. This study was undertaken to examine the characteristics of the top 100 most frequently cited articles (so-called "citation classics") on traumatic spinal cord injury (SCI) that were published between 1986 and 2003, and to compare this selected professional literature with the consumers' perspective on the key issues in SCI research. The 100 top-cited articles on traumatic SCI were identified using the Internet database of the Science Citation Index Expanded and the Web of Science with the terms "spinal cord injury" and "spinal cord injuries." Meeting abstracts, letters, and editorials were excluded. No language restriction was applied. From a consumers' perspective, the areas of greatest interest for people with SCI as reported in two previous large-scale surveys include motor function, bowel and bladder control, sexual function, and pain. The final list of citation classics on traumatic SCI included 82 original articles and 18 article reviews, which were cited 146 times on average. Topics on basic science (63%) were more frequent than clinical studies (37%). The years of publication were distributed in a bell-shape curve with a peak between 1992 and 1994. North American and European centers (99%) led the list of the citation classics. Most of the top 100 most frequently cited articles on traumatic SCI (63%) explicitly focused on at least one of the topics of greatest interest to individuals with SCI. Motor function was the leading topic in the matching list between professional literature and consumers' perspective. This bibliometric analysis, for the first time, identifies the key features of the citation classics on traumatic SCI between 1986 and 2003, a period that represents one of an unprecedented increase in knowledge in this field. The 100 top-cited peer-reviewed articles have been predominantly focused on basic science SCI research indicating a need for greater bench-to-bedside translational studies in SCI research. Although the body of this top-cited professional literature mostly matches with the consumers' perspective, most of this research has been focused on motor function assessment and recovery following SCI.

Bibliometrics↗

PubMed2006

Inhibition of Fas-mediated apoptosis through administration of soluble Fas receptor improves functional outcome and reduces posttraumatic axonal degeneration after acute spinal cord injury.

Fas receptor activation has been implicated in inflammatory responses, programmed cell death, Wallerian degeneration in neural injury and the axotomy induced death of motoneurons. Recent work using transection models of spinal cord injury (SCI) demonstrated that neutralization of Fas ligand with antibodies may promote axonal regeneration and functional recovery. Moreover, recent studies from our laboratory in mutant mice with deficient expression of Fas, show reduced cell death and enhanced behavioural recovery after SCI. The present paper examines the effects of soluble Fas receptor (sFasR) administration on inhibition of Fas receptor-Fas ligand interaction in the setting of acute SCI in vitro and in vivo. An in vitro model of SCI demonstrated that sFasR administration decreases cell death as assessed by propidium iodide fluorescence. Furthermore, in a moderately severe in vivo clip compression model of SCI at C7-T1, we demonstrate that subarachnoid infusion of sFasR results in increased neuron and oligodendrocyte survival, improved tissue and long tract axonal preservation, reduced apoptotic cell death and enhanced functional neurological outcome after acute SCI. These results strongly suggest that inhibiting Fas receptor activation is neuroprotective after acute SCI and that this strategy may have important translational significance.

Animals↗

PubMed2006

Surgical decision making for unstable thoracolumbar spine injuries: results of a consensus panel review by the Spine Trauma Study Group.

OBJECTIVES: The optimal surgical approach and treatment of unstable thoracolumbar spine injuries are poorly defined owing to a lack of widely accepted level I clinical literature. This lack of evidence-based standards has led to varied practice patterns based on individual surgeon preferences. The purpose of this study was to survey the leaders in the field of spine trauma to define the major characteristics of thoracolumbar injuries that influence their surgical decision making. In the absence of good scientific data, expert consensus opinions may provide surgeons with a practical framework to guide therapy and to conduct future research. METHODS: A panel of 22 leading spinal surgeons from 20 level I trauma centers in seven countries met to discuss the indications for surgical approach selection in unstable thoracolumbar injuries. Injuries were presented to the surgeons in a case scenario survey format. Preferred surgical approaches to the clinical scenarios were tabulated and comments weighed. RESULTS: All members of the panel agreed that three independent characteristics of thoracolumbar injuries carry primary importance in surgical decision making: the injury morphology, the neurologic status of the patient, and the integrity of the posterior ligaments. Six clinical scenarios based on the neurologic status of the patient (intact, incomplete, or complete) and on the status of the posterior ligamentous complex (intact or disrupted) were created, and consensus treatment approaches were described. Additional circumstances capable of altering the treatments were acknowledged. CONCLUSIONS: Decision making for the surgical treatment of thoracolumbar injuries is largely dependent on three patient characteristics: injury morphology, neurologic status, and posterior ligament integrity. A logical and practical decision-making process based on these characteristics may guide treatment even for the most complicated fracture patterns.

Algorithms↗

PubMed2006

Agreement between orthopedic surgeons and neurosurgeons regarding a new algorithm for the treatment of thoracolumbar injuries: a multicenter reliability study.

INTRODUCTION: Considerable variability exists in the management of thoracolumbar (TL) spine injuries. Although there are many influences, one significant factor may be the treating surgeon's specialty and training (ie, orthopedic surgery vs. neurosurgery). Our objective was to assess the agreement between spinal orthopedic and neurologic surgeons in rating the severity of TL spine injuries with a new treatment algorithm. This information could be important in establishing consensus-based protocols for managing these challenging injuries. METHODS: Twenty-eight spinal surgeons (8 neurosurgeons and 20 orthopedic surgeons) reviewed 56 TL injury case histories. Each case was classified and scored according to the TL injury severity score (TLISS). The case histories were reordered and the physicians repeated the exercise 3 months later. At both intervals the surgeons were asked if they agreed with the final treatment recommendation of the TLISS algorithm. The reliability and decision validity of the TLISS was compared. RESULTS: Between-group interrater reliability was similar to within group reliabilities. Intrarater reliability was also similar between groups. The between speciality interrater reliability of the TLISS management recommendation was moderate (74% agreement, kappa=0.532). Orthopedic and neurosurgeons agreed with the TLISS management recommendation 91.4% and 94.4% of the time, respectively. CONCLUSIONS: The TLISS demonstrated good reliability in terms of intraobserver and interobserver agreement on the algorithmic treatment recommendations. The recommendation for operation seems to be consistent between fellowship-trained orthopedic and neurosurgical spine surgeons. This type of classification system may reduce the existing variability and initial management decision for treatment of TL injuries.

Algorithms↗

PubMed2006

Intrarater and interrater reliability and validity in the assessment of the mechanism of injury and integrity of the posterior ligamentous complex: a novel injury severity scoring system for thoracolumbar injuries. Invited submission from the Joint Section Meeting On Disorders of the Spine and Peripheral Nerves, March 2005.

OBJECT: A new classification and treatment algorithm for thoracolumbar injuries was recently introduced by Vaccaro and colleagues in 2005. A thoracolumbar injury severity scale (TLISS) was proposed for grading and guiding treatment for these injuries. The scale is based on the following: 1) the mechanism of injury; 2) the integrity of the posterior ligamentous complex (PLC); and 3) the patient's neurological status. The reliability and validity of assessing injury mechanism and the integrity of the PLC was assessed. METHODS: Forty-eight spine surgeons, consisting of neurosurgeons and orthopedic surgeons, reviewed 56 clinical thoracolumbar injury case histories. Each was classified and scored to determine treatment recommendations according to a novel classification system. After 3 months the case histories were reordered and the physicians repeated the exercise. Validity of this classification was good among reviewers; the vast majority (> 90%) agreed with the system's treatment recommendations. Surgeons were unclear as to a cogent description of PLC disruption and fracture mechanism. CONCLUSIONS: The TLISS demonstrated acceptable reliability in terms of intra- and interobserver agreement on the algorithm's treatment recommendations. Replacing injury mechanism with a description of injury morphology and better definition of PLC injury will improve inter- and intraobserver reliability of this injury classification system.

Algorithms↗

PubMed2006

Surgical management of tethered cord syndrome in adults: indications, techniques, and long-term outcomes in 60 patients.

OBJECT: The adult presentation of tethered cord syndrome (TCS) is well recognized but continues to pose significant diagnostic and management challenges. The authors performed a retrospective study of clinical outcomes after neurosurgical intervention in 60 adults with TCS. METHODS: All patients who underwent detethering surgery for caudal cord tethering at Toronto Western Hospital between August 1993 and 2004 were identified. Their clinical charts, operative records, and follow-up data were reviewed. Detethering procedures were performed in 62 patients (age range 17-72 years) for TCS of various origins. Long-term (mean 41.5 months) follow-up data were obtained in 60 patients. The tethering lesions were tight terminal filum in 29 patients, postrepair myelomeningocele in 15, lipomyelomeningocele/lipoma in nine, split cord malformation in four, and arachnoidal adhesions in three. Fifty-nine patients presented with progressive pain and/or neurological dysfunction. One patient underwent prophylactic sectioning of the terminal filum. Most patients (71%) had bladder dysfunction at presentation. Microsurgical release of the tethered cord was performed in each case while using multimodality intraoperative neurophysiological monitoring. The most common complication was cerebrospinal fluid leakage, which occurred in nine patients and was managed by reinforcement sutures in four patients, temporary external drainage in three, and the placement of a lumboperitoneal shunt in two. Infective complications included superficial wound infection in three patients, meningitis in one, and urinary tract infection in one. One patient who had undergone multiple previous intradural procedures experienced worsened foot weakness postoperatively. Another patient experienced temporary unilateral lower-limb numbness. At follow up, improvement was noted in the majority of patients presenting with back (78%) and leg (83%) pain. Improvement was more likely in patients with preoperative motor weakness than in those with sensory deficits. Overall, neurological status was improved or stabilized in 90% of patients. Subjective improvement in bladder function was noted in 50% of patients with bladder dysfunction at presentation. CONCLUSIONS: Surgery in adult patients with TCS is safe and effective for improving pain and neurological status in the majority of patients; however, patients who have undergone previous intradural detethering procedures in general fare less well, and considerable judgment is required in their management.

Adolescent↗

PubMed2005

Functional changes in genetically dysmyelinated spinal cord axons of shiverer mice: role of juxtaparanodal Kv1 family K+ channels.

Axonal dysfunction after spinal cord injury (SCI) and other types of neurotrauma is associated with demyelination and exposure of juxtaparanodal K+ channels. In this study, sucrose gap electrophysiology using selective and nonselective K+ channel blockers, confocal immunohistochemistry, and Western blotting were used to study the role of Kv1.1 and Kv1.2 K+ channel subunits in dysmyelination-induced spinal cord axonal dysfunction in shiverer mice, which lack the gene encoding myelin basic protein (MBP) and exhibit incomplete myelin sheath formation on CNS axons. The shiverer spinal cord axons exhibited smaller amplitude of compound action potentials (CAPs), reduced conduction velocity, reduced excitability, and greater degree of high-frequency conduction failure. The "fast" K+ channel blocker 4-aminopyridine, the toxin DTX-I, which targets the Kv1.1 and Kv1.2, but not DTX- K, which has higher selectivity for Kv1.1, increased the amplitude and area of CAPs of shiverer mice spinal cord axons but had insignificant effects in wild-type mice. Confocal immunohistochemistry showed that, unlike wild-type mice, which have a precise juxtaparanodal localization of the Kv1.l and Kv1.2 K+ channel subunits, shiverer mouse axons displayed a dispersed distribution of these subunits along the internodes. In contrast, the Kv1.l and Kv1.2 subunits, Na+ channels remained highly localized to the nodal regions. Western blotting showed an increased expression of Kv 1.1 and 1.2 in the shiverer mouse spinal cord. These results provide evidence that the neurological deficits associated with myelin deficiency reflect the altered distribution and expression of the K+ channel subunits Kv1.l and Kv1.2 along the internodes of spinal cord axons associated with the biophysical consequences caused by alterations in the myelin sheaths.

Action Potentials↗

PubMed2005

Anterior cervical screw extrusion leading to acute upper airway obstruction: case report.

STUDY DESIGN: Case report of late postoperative complication. SUMMARY OF BACKGROUND DATA: There have been a number of reports of migration and extrusion of cervical fusion instrumentation. The majority of such cases have a benign outcome. To our knowledge, cervical instrumentation extrusion resulting in prevertebral abscess and acute airway obstruction has not been reported. METHODS: A 56-year-old man who had undergone a prior C3-C6 anterior cervical decompression and fusion presented to a hospital with dysphagia and acute airway obstruction requiring an emergency tracheostomy. His neck radiograph showed that a C6 screw was missing compared to prior films. Magnetic resonance imaging showed a large prevertebral abscess anterior to C2-C7 causing complete upper airway obstruction. RESULTS: He underwent surgical drainage of the abscess and had a good neurologic recovery. CONCLUSIONS: We report a case of acute upper airway obstruction from prevertebral abscess, likely secondary to a loosened anterior cervical screw penetrating the prevertebral soft tissue. In contrast to case reports in the literature involving instrumentation extrusion with a usually benign outcome, our case presented with a life-threatening condition.

Airway Obstruction↗