Unbiased Recursive Partitioning Enables Robust and Reliable Outcome Prediction in Acute Spinal Cord Injury.

Neurological disorders usually present very heterogeneous recovery patterns. Nonetheless, accurate prediction of future clinical end-points and robust definition of homogeneous cohorts are necessary for scientific investigation and targeted care. For this, unbiased recursive partitioning with conditional inference trees (URP-CTREE) have received increasing attention in medical research, especially, but not limited to traumatic spinal cord injuries (SCIs). URP-CTREE was introduced to SCI as a clinical guidance tool to explore and define homogeneous outcome groups by clinical means, while providing high accuracy in predicting future clinical outcomes. The validity and predictive value of URP-CTREE to provide improvements compared with other more common approaches applied by clinicians has recently come under critical scrutiny. Therefore, a comprehensive simulation study based on traumatic, cervical complete spinal cord injuries provides a framework to investigate and quantify the issues raised. First, we assessed the replicability and robustness of URP-CTREE to identify homogeneous subgroups. Second, we implemented a prediction performance comparison of URP-CTREE with traditional statistical techniques, such as linear or logistic regression, and a novel machine learning method. URP-CTREE's ability to identify homogeneous subgroups proved to be replicable and robust. In terms of prediction, URP-CTREE yielded a high prognostic performance comparable to a machine learning algorithm. The simulation study provides strong evidence for the robustness of URP-CTREE, which is achieved without compromising prediction accuracy. The slightly lower prediction performance is offset by URP-CTREE's straightforward interpretation and application in clinical settings based on simple, data-driven decision rules.

The Central Cord Score: A Novel Classification and Scoring System Specific to Acute Traumatic Central Cord Syndrome.

BACKGROUND: Acute traumatic central cord syndrome (ATCCS) is the most common form of spinal cord injury in the United States. Treatment remains controversial, which is a consequence of ATCCS having an inherently different natural history from conventional spinal cord injury, thus requiring a separate classification system. We devised a novel Central Cord Score (CCscore), which both guides treatment and tracks improvement over time with symptoms specific to ATCCS. METHODS: Medical records of patients with a diagnosis of ATCCS were retrospectively reviewed at a single institution. The CCscore was devised based on signs, symptoms, and imaging findings we believed to be critical in assessing severity of ATCCS. Numeric values were assigned for distal upper extremity motor strength, upper extremity sensation, ambulatory status, magnetic resonance imaging cord signal, and urinary retention. RESULTS: We identified 51 patients with follow-up data; there were 17 cases of mild injury (CCscore 1-5), 23 moderate cases (CCscore 6-10), and 11 severe cases (CCscore 11-15). Patients treated surgically had significantly greater improvement in upper extremity motor scores and total CCscore only up to 3 months. In terms of timing of surgery, patients treated <24 hours after injury had significantly improved upper extremity motor scores and overall CCscores at last follow-up of ≥3 months. CONCLUSIONS: Based on these data and their alignment with past literature, the CCscore is able to objectively and specifically categorize the severity and outcome of ATCCS, which represents a step forward in the quest to determine the ultimate efficacy and timing of surgery for ATCCS.

Early Predictors of Neurological Outcomes After Traumatic Spinal Cord Injury: A Systematic Review and Proposal of a Conceptual Framework.

BACKGROUND: Neurological outcomes after traumatic spinal cord injury are variable and depend on patient-, trauma-, and treatment-related factors as well as on spinal cord injury characteristics, imaging, and biomarkers. OBJECTIVE: The aims of the study were to identify and classify the early predictors of neurological outcomes after traumatic spinal cord injury. DATA SOURCES: The Medline, PubMed, Embase, and the Cochrane Central Database were searched using medical subject headings. The search was extended to the reference lists of identified studies. STUDY ELIGIBILITY CRITERIA: The study eligibility criteria were assessment of neurological outcomes as primary or secondary outcome, predictors collected during the acute phase after traumatic spinal cord injury, and multivariate design. PARTICIPANTS: The participants were adult patients with traumatic spinal cord injury followed at least 3 mos after injury. STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of studies was assessed by two independent reviewers using the Study Quality Assessment Tools for Observational Cohort and Cross-sectional Studies. The studies' narrative synthesis relied on a classification of the predictors according to quantity, quality, and consistency of the evidence. Results were summarized in a conceptual framework. RESULTS: Forty-nine articles were included. The initial severity of traumatic spinal cord injury (American Spinal Injury Association Impairment Scale, motor score, and neurological level of injury) was the strongest predictor of neurological outcomes: patients with more severe injury at admission presented poor neurological outcomes. Intramedullary magnetic resonance imaging signal abnormalities were also associated with neurological outcomes, as the presence of intramedullary hemorrhage was a factor of poor prognosis. Other largely studied predictors, such as age and surgical timing, showed some inconsistency in results depending on cutoffs. Younger age and early surgery were generally associated with good outcomes. Although widely studied, other factors, such as vertebral and associated injuries, failed to show association with outcomes. Cerebrospinal fluid inflammatory biomarkers, as emerging factors, were significantly associated with outcomes. CONCLUSIONS: This study provides a comprehensive review of predictors of neurological outcomes after traumatic spinal cord injury. It also highlights the heterogeneity of outcomes used by studies to assess neurological recovery. The proposed conceptual framework classifies predictors and illustrates their relationships with outcomes.

Evaluating the Severity and Prognosis of Acute Traumatic Cervical Spinal Cord Injury: A Novel Classification Using Diffusion Tensor Imaging and Diffusion Tensor Tractography.

STUDY DESIGN: Retrospective observational cohort study. OBJECTIVE: We explored the relationship between diffusion tensor imaging (DTI) parameters and prognosis in patients with acute traumatic cervical spinal cord injury (ATCSCI). SUMMARY OF BACKGROUND DATA: DTI has been used to diagnose spinal cord injury; nevertheless, its role remains controversial. METHODS: We analyzed retrospectively 24 patients with ATCSCI who were examined using conventional T2-weighted imaging and DTI. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were recorded at the injured site. Diffusion tensor tractography (DTT) was used to measure the spinal cord white matter fiber volume (MWFV). American Spinal Injury Association (ASIA) grades were recorded. Correlations between DTI parameters and ASIA scores were evaluated using Spearman correlation coefficients. RESULTS: FA values at injured sites were significantly lower than those of the control group, whereas ADC values in injured and control groups were not significantly different. DTT revealed that ATCSCI could be divided into four types: Type A1-complete rupture of spinal cord white matter fiber (MWF); Type A2-partial rupture of MWF; Type B-most MWF retained with severe compression or abnormal fiber conduction direction; and Type C-MWF basically complete with slight compression. Preoperative physical examinations revealed complete injury (ASIA A) in patients with A1 (n = 4) and A2 (n = 4). The ASIA grades or scores of A2 were improved to varying degrees, whereas there was no significant improvement in A1. FA values and MWFV of ASIA B, C, and D were significantly higher than those of ASIA A. FA and MWFV were correlated with ASIA motor score preoperatively and at final follow-up. CONCLUSION: We propose a classification for the severity of ATCSCI based on DTI and DTT that may explain why some patients with ASIA A recover, whereas others do not.Level of Evidence: 4.

Relationship between Machine-Learning Image Classification of T2-Weighted Intramedullary Hypointensity on 3 Tesla Magnetic Resonance Imaging and Clinical Outcome in Dogs with Severe Spinal Cord Injury.

Early prognostic information in cases of severe spinal cord injury can aid treatment planning and stratification for clinical trials. Analysis of intraparenchymal signal change on magnetic resonance imaging has been suggested to inform outcome prediction in traumatic spinal cord injury. We hypothesized that intraparenchymal T2-weighted hypointensity would be associated with a lower potential for functional recovery and a higher risk of progressive neurological deterioration in dogs with acute, severe, naturally occurring spinal cord injury. Our objectives were to: 1) demonstrate capacity for machine-learning criteria to identify clinically relevant regions of hypointensity and 2) compare clinical outcomes for cases with and without such regions. A total of 95 dogs with complete spinal cord injury were evaluated. An image classification system, based on Speeded-Up Robust Features (SURF), was trained to recognize individual axial T2-weighted slices that contained hypointensity. The presence of such slices in a given transverse series was correlated with a lower chance of functional recovery (odds ratio [OR], 0.08; confidence interval [CI], 0.02-0.38; p < 10-3) and with a higher risk of neurological deterioration (OR, 0.14; 95% CI, 0.05-0.42; p < 10-3). Identification of intraparenchymal T2-weighted hypointensity in severe, naturally occurring spinal cord injury may be assisted by an image classification tool and is correlated with functional recovery.

Characterizing Natural Recovery after Traumatic Spinal Cord Injury.

The predominant tool used to predict outcomes after traumatic spinal cord injury (SCI) is the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), in association with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). These measures have evolved based on analyses of large amounts of longitudinal neurological recovery data published in numerous separate studies. This article reviews and synthesizes published data on neurological recovery from multiple sources, only utilizing data in which the sacral sparing definition was applied for determination of completeness. Conversion from a complete to incomplete injury is more common in tetraplegia than paraplegia. The majority of AIS conversion and motor recovery occurs within the first 6-9 months, with the most rapid rate of motor recovery occurring in the first three months after injury. Motor score changes, as well as recovery of motor levels, are described with the initial strength of muscles as well as the levels of the motor zone of partial preservation influencing the prognosis. Total motor recovery is greater for patients with initial AIS B than AIS A, and greater after initial AIS C than with motor complete injuries. Older age has a negative impact on neurological and functional recovery after SCI; however, the specific age (whether >50 or >65 years) and underlying reasons for this impact are unclear. Penetrating injury is more likely to lead to a classification of a neurological complete injury compared with blunt trauma and reduces the likelihood of AIS conversion at one year. There are insufficient data to support gender having a major effect on neurological recovery after SCI.

Establishing the Injury Severity of Subaxial Cervical Spine Trauma: Validating the Hierarchical Nature of the AO Spine Subaxial Cervical Spine Injury Classification System.

STUDY DESIGN: Global cross-sectional survey. OBJECTIVE: The aim of this study was to validate the AO Spine Subaxial Cervical Spine Injury Classification by examining the perceived injury severity by surgeon across AO geographical regions and practice experience. SUMMARY OF BACKGROUND DATA: Previous subaxial cervical spine injury classifications have been limited by subpar interobserver reliability and clinical applicability. In an attempt to create a universally validated scheme with prognostic value, AO Spine established a subaxial cervical spine injury classification involving four elements: injury morphology, facet injury involvement, neurologic status, and case-specific modifiers. METHODS: A survey was sent to 272 AO Spine members across all geographic regions and with a variety of practice experience. Respondents graded the severity of each variable of the classification system on a scale from zero (low severity) to 100 (high severity). Primary outcome was to assess differences in perceived injury severity for each injury type over geographic regions and level of practice experience. RESULTS: A total of 189 responses were received. Overall, the classification system exhibited a hierarchical progression in subtype injury severity scores. Only three subtypes showed a significant difference in injury severity score among geographic regions: F3 (floating lateral mass fracture, P = 0.04), N3 (incomplete spinal cord injury, P = 0.03), and M2 (critical disk herniation, P = 0.04). When stratified by surgeon experience, pairwise comparison showed only two morphological subtypes, B1 (bony posterior tension band injury, P = 0.02) and F2 (unstable facet fracture, P = 0.03), and one neurologic subtype (N3, P = 0.02) exhibited a significant difference in injury severity score. CONCLUSION: The AO Spine Subaxial Cervical Spine Injury Classification System has shown to be reliable and suitable for proper patient management. The study shows this classification is substantially generalizable by geographic region and surgeon experience, and provides a consistent method of communication among physicians while covering the majority of subaxial cervical spine traumatic injuries.Level of Evidence: 4.

Updates of the International Standards for Neurologic Classification of Spinal Cord Injury: 2015 and 2019.

The International Standards for Neurologic Classification of Spinal Cord Injury (ISNCSCI) are the most widely used classification system in spinal cord injury medicine. The purpose of the ISNCSCI is to ensure accurate and consistent communication among patients, clinicians, and researchers. Since its first publication in 1982, the ISNCSCI has continued to evolve with the latest updates and revisions published in 2015 and 2019. The updates were incorporated into the 2019 ISNCSCI worksheet and booklet, and the International Standards Training e-Learning Program. This article details the ISNCSCI update from 2015 and revision in 2019.

A Comparison of Diagnostic Stability of the ASIA Impairment Scale Versus Frankel Classification Systems for Traumatic Spinal Cord Injury.

OBJECTIVE: To determine whether the "sacral sparing" definition for completeness of traumatic spinal cord injury (SCI) is a more stable definition than the previously used Frankel Classification. DESIGN: Retrospective analysis of individuals enrolled in the Spinal Cord Injury Model Systems (SCIMS) database between 2011 and 2018. SETTING: SCIMS centers. PARTICIPANTS: Individuals (N=804) with traumatic SCI who were at least 16 years old at time of injury, were admitted to rehabilitation within 30 days, had American Spinal Injury Association Impairment Scale (AIS) grades A-D at admission, and had complete neurologic data at the time of admission and 1 year. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Frankel and AIS scores were computed for a cohort of 804 eligible cases. Stability was compared between the 2 classification systems by calculating the proportions of cases in which regression (conversion to a more severe impairment level) was observed. RESULTS: A larger proportion of individuals classified with "incomplete" injuries (grades B-D) at the time of admission using the Frankel system regressed to complete status at 1 year compared with the AIS criteria (9.4% vs 2.0%). Those with grade B injuries regressed to grade A more often using the Frankel system compared with the AIS system (19.7% to 5.4%). A larger proportion of people diagnosed as Frankel grade C or D regressed to Frankel grade A compared with individuals diagnosed as AIS grade C or D who regressed to AIS grade A (5.0% to 1.1%). CONCLUSIONS: More individuals diagnosed with neurologically incomplete SCI regressed to complete status at 1 year when using the Frankel system compared with AIS classification, which is based on sacral sparing. This reinforces the finding that the "sacral sparing" definition is a more stable classification in traumatic SCI.

Can a relatively large spinal cord for the dural sac influence severity of paralysis in elderly patients with cervical spinal cord injury caused by minor trauma?

Retrospective reviewThe degree of spinal cord compression and bony spinal canal stenosis are risk factors for the occurrence of spinal cord injury (SCI) without major fracture or dislocation, but they do not affect the severity of neurological symptoms. However, whether a relatively large spinal cord for the dural sac influences the severity of symptoms in SCI cases is unknown.The purpose of this study was to verify the influence of spinal cord size relative to dural sac on the severity of paralysis in elderly patients with cervical SCI caused by minor trauma.Subjects were 50 elderly patients with SCI caused by falls on flat ground. At 72 hours after injury, neurological assessment was performed using the Japanese Orthopaedic Association (JOA) scoring system. Bony canal anteroposterior diameters (APD) at mid C5 vertebral body were measured with computed tomography. We measured dural sac and spinal cord APD at the injured level and mid C5 with magnetic resonance imaging. Spinal cord compression ratio was calculated by dividing spinal cord at the injured level by spinal cord at mid C5. As the evaluation of spinal cord size relative to the dural sac, spinal cord/dural sac ratio was calculated at the injured level and mid C5. To clarify the factors influencing the severity of paralysis, the relationships between JOA score and those parameters were examined statistically.A significant negative correlation was observed between JOA score and spinal cord/dural sac ratio at mid C5. No clear relationship was observed between JOA score and bony canal APD or spinal cord compression ratio.In elderly patients with SCI caused by minor trauma, a relatively large spinal cord for the dural sac was shown to be a factor that influences the severity of paralysis. This result can be useful for the treatment and prevention of SCI in the elderly.

Transforming Research and Clinical Knowledge in Spinal Cord Injury (TRACK-SCI): an overview of initial enrollment and demographics.

OBJECTIVE: Traumatic spinal cord injury (SCI) is a dreaded condition that can lead to paralysis and severe disability. With few treatment options available for patients who have suffered from SCI, it is important to develop prospective databases to standardize data collection in order to develop new therapeutic approaches and guidelines. Here, the authors present an overview of their multicenter, prospective, observational patient registry, Transforming Research and Clinical Knowledge in SCI (TRACK-SCI). METHODS: Data were collected using the National Institute of Neurological Disorders and Stroke (NINDS) common data elements (CDEs). Highly granular clinical information, in addition to standardized imaging, biospecimen, and follow-up data, were included in the registry. Surgical approaches were determined by the surgeon treating each patient; however, they were carefully documented and compared within and across study sites. Follow-up visits were scheduled for 6 and 12 months after injury. RESULTS: One hundred sixty patients were enrolled in the TRACK-SCI study. In this overview, basic clinical, imaging, neurological severity, and follow-up data on these patients are presented. Overall, 78.8% of the patients were determined to be surgical candidates and underwent spinal decompression and/or stabilization. Follow-up rates to date at 6 and 12 months are 45% and 36.3%, respectively. Overall resources required for clinical research coordination are also discussed. CONCLUSIONS: The authors established the feasibility of SCI CDE implementation in a multicenter, prospective observational study. Through the application of standardized SCI CDEs and expansion of future multicenter collaborations, they hope to advance SCI research and improve treatment.

George Chance and Frank Holdsworth: Understanding Spinal Instability and the Evolution of Modern Spine Injury Classification Systems.

The concept of spinal cord injury has existed since the earliest human civilizations, with the earliest documented cases dating back to 3000 BC under the Egyptian Empire. Howevr, an understanding of this field developed slowly, with real advancements not emerging until the 20th century. Technological advancements including the dawn of modern warfare producing mass human casualties instigated revolutionary advancement in the field of spine injury and its management. Spine surgeons today encounter "Chance" and "Holdsworth" fractures commonly; however, neurosurgical literature has not explored the history of these physicians and their groundbreaking contributions to the modern understanding of spine injury. A literature search using a historical database, Cochrane, Google Scholar, and PubMed was performed. As needed, hospitals and native universities were contacted to add their original contributions to the literature. George Quentin Chance, a Manchester-based British physician, is well known to many as an eminent radiologist of his time who described the eponymous fracture in 1948. Sir Frank Wild Holdsworth (1904-1969), a renowned British orthopedic surgeon who laid a solid foundation for rehabilitation of spinal injuries under the aegis of the Miners' Welfare Commission, described in detail the management of thoraco-lumbar junctional rotational fracture. The work of these 2 men laid the foundation for today's understanding of spinal instability, which is central to modern spine injury classification and management algorithms. This historical vignette will explore the academic legacies of Sir Frank Wild Holdsworth and George Quentin Chance, and the evolution of spinal instability and spine injury classification systems that ensued from their work.

The sacral exam-what is needed to best care for our patients?

Sacral reflexes are important to allow the SCI practitioner to gain information about the state of the sacral spinal cord segments. The presence of the bulbocavernosus and/or the anal wink reflex indicate an intact spinal reflex arc and reflex conal autonomic function (as part of the upper motor neuron syndrome); their absence defines a lower motor neuron syndrome. The assessment of sacral reflexes helps predict the type of bladder, bowel and sexual functions and the related therapeutic interventions. We suggest adding the sacral component of the International Standards for the Assessment of Autonomic Function after SCI (ISAFSCI) to the International Standards for the Neurologic Classification of Spinal Cord Injury (ISNCSCI) examination so there can be a detailed description of these important functions. As an alternative, the performance of sacral reflexes should be routinely required as part of the neurologic examination after SCI. Whether the sacral motor neuron system is classified as upper or lower motor neuron injury is also quite useful and as such should be present in the ISCNSCI.

Are Body Composition, Strength, and Functional Independence Similarities Between Spinal Cord Injury Classifications? A Discriminant Analysis.

CONTEXT: There seems to be no consensus on which aspects better distinguish the different levels of spinal cord injury regarding body composition, strength, and functional independence. OBJECTIVE: The study aimed to determine which variables better differentiate tetraplegia (TP) from paraplegia and high paraplegia (HP) from low paraplegia (LP). DESIGN: Cross-sectional study. SETTING: Rehabilitation hospital network. PATIENTS: Forty-five men with spinal cord injury, n = 15 for each level (TP, HP, and LP) causing complete motor impairment (American Spinal Injury Association Impairment Scale: A or B) were enrolled in the study. MAIN OUTCOME MEASURES: The 1-maximum repetition test, functional independence measure, spinal cord independence measure, and body composition (skinfold sum, body fat percentage, and body mass index) were assessed. Discriminant analysis was carried out using the Wilks lambda method to identify which strength and functional variables can significantly discriminate subjects for injury classification (TP, HP, and LP). RESULTS: The discriminant variable for TP versus HP was body mass index and for TP versus LP was 1-maximum repetition (P ≤ .05). There were no variables that discriminated HP versus LP. CONCLUSIONS: The discriminant variables for TP versus HP and TP versus LP were body mass index and 1-maximum repetition, respectively. The results showed that HP and LP are similar for strength and functional variables.

Assessing the ability of the Sacral Autonomic Standards to document bladder and bowel function based upon the Asia Impairment Scale.

Study design: Retrospective review of data. Objective: To determine if there is a relationship between the Asia Impairment Scale (AIS) and the bladder and bowel components of the International Standards to Document Remaining Autonomic Function after SCI (ISAFSCI). Setting: University-Based Academic Rehabilitation Program. Methods: Retrospective cross-sectional study assessing International Standards for Neurologic Classification After SCI (ISNCSCI) examination along with bladder and bowel components of the ISAFSCI. Results: Subjects with AIS A injuries were statistically less likely to have history of bladder control and bowel control per investigator determination and bladder sensation via self-report versus patients categorized with AIS B injuries. Self-reported history of bowel sensation and control of voiding were more likely in subjects with C, D, or E injuries than with B injuries. Bowel and bladder control as determined by investigator and bladder and bowel sensation and control as self-reported were all statistically less likely in persons with AIS A injuries versus CDE. Conclusions: This retrospective study provides initial data regarding components of the bladder and bowel sections of the sacral ISAFSCI and AIS. Further prospective research is needed to further characterize the relationship between retention of bladder and bowel sensation and function and the AIS. We suggest that incorporation of the sacral components of the ISAFSCI into the ISNCSCI may be beneficial to obtain further information about retention of sacral function with specific patterns of injury.

The standing and walking assessment tool for individuals with spinal cord injury: A qualitative study of validity and clinical use.

Context/Objective: The Spinal Cord Injury (SCI) Standing and Walking Assessment Tool (SWAT) combines stages of walking recovery with measures of balance and walking. It standardizes the timing and content of walking assessment in inpatient rehabilitation. The study aims were: (1) Evaluate the content validity of the SWAT stages of walking recovery, and (2) Understand physical therapists' (PTs) experiences using the SWAT to gauge acceptance, implementation and impact. Design: Qualitative, exploratory study. Setting: Nine Canadian rehabilitation hospitals. Participants: Thirty-four PTs who had used the SWAT ≥10 times. Interventions: Seven focus group meetings were completed. Semi-structured questions queried the content, order and spacing of SWAT stages, and current SWAT use (i.e. processes, challenges, facilitators, impact on practice). Meetings were audio-recorded and transcribed. Themes and categories were derived through a conventional content analysis. Outcome Measure: Not applicable. Results: PTs agreed with the ordering and content of the SWAT stages, but reported unequal spacing between stages. Three themes related to PTs' use of the SWAT were identified: (1) Variable process: SWAT implementation varied across sites, PTs and patients. (2) Implementation challenges: unfamiliarity of the SWAT, lack of time, not required by place of work, and patients who are outliers or have poor gait quality. (3) Potential to influence clinical decision-making: the SWAT did not influence clinical decisions, but PTs recognized the potential of the tool to do so. Conclusions: Content validity of the SWAT stages was supported and implementation challenges identified. Variability in SWAT implementation may reflect the heterogeneity and person-centeredness of SCI rehabilitation.