Abstract:Objective: Although there are several classifications for cervical myelopathy, these do not take differences between spinal cord segments into account. Moreover, there has been no report of stress analyses for individual segments to date. Methods: By using the finite element method, we constructed 3-dimensional spinal cord models comprised of gray matter, white matter, and pia mater of the second to eighth cervical vertebrae (C2-C8). We placed compression components (disc and yellow ligament) at the front and … Show more
“…Finite-element modeling has replicated this concept, identifying thresholds for ventral compression to exceed before mechanical stress is detected. 83,84 This is also supported by histological studies indicating the spinal cord tolerance of some compression, 85,86 with a re-alignment of spinal pathways, and cadaveric models demonstrating tension-related deformation before compression-related deformation. 82,87,88 Figure 5. Case Example: A single level disc prolapse without deformity or instability (MRI, T2 Weighted Sagittal Image).…”
Section: Introductionsupporting
confidence: 52%
“…In DCM, the mechanical stress experienced will be complicated by how these forces interact, 84 for example, in a finite-element model of static compression of the spinal cord, elasticity measured using ultrasound reduced when the spinal cord was compressed. 113 These forces too, will have been exhibited in combination, within the existing pre-clinical models that underpin our current investigations of DCM.…”
Study Design Literature Review (Narrative) Objective To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5. Methods Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual’s susceptibility, including the proposal of a new framework. Results Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual’s vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time. Conclusion Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease.
“…Finite-element modeling has replicated this concept, identifying thresholds for ventral compression to exceed before mechanical stress is detected. 83,84 This is also supported by histological studies indicating the spinal cord tolerance of some compression, 85,86 with a re-alignment of spinal pathways, and cadaveric models demonstrating tension-related deformation before compression-related deformation. 82,87,88 Figure 5. Case Example: A single level disc prolapse without deformity or instability (MRI, T2 Weighted Sagittal Image).…”
Section: Introductionsupporting
confidence: 52%
“…In DCM, the mechanical stress experienced will be complicated by how these forces interact, 84 for example, in a finite-element model of static compression of the spinal cord, elasticity measured using ultrasound reduced when the spinal cord was compressed. 113 These forces too, will have been exhibited in combination, within the existing pre-clinical models that underpin our current investigations of DCM.…”
Study Design Literature Review (Narrative) Objective To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5. Methods Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual’s susceptibility, including the proposal of a new framework. Results Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual’s vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time. Conclusion Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease.
“…27 There was a pathological study of CSM in a case in which the hind tract was not impaired, but the anterior and lateral tracts were severely impaired, suggesting that there is variation in the mode of progression of myelopathy. 28 Previous electrophysiological 12,15,29 and biomechanical studies [30][31][32] indicated that the lateral parts of the posterior column (Burdach tract), lateral corticospinal tract, and medial part of the posterior column (Goll tract; in this order) are more likely to be impaired by DCM. Therefore, the symptoms of DCM should expand from hand impairment to gait and urinary impairment as the myelopathy becomes more severe.…”
OBJECTIVE
Neurological and imaging findings play significant roles in the diagnosis of degenerative cervical myelopathy (DCM). Consistency between neurological and imaging findings is important for diagnosing DCM. The reasons why neurological findings exhibit varying sensitivity for DCM and their associations with radiological findings are unclear. This study aimed to identify associations between radiological parameters and neurological findings in DCM and elucidate the utility of concordance between imaging and neurological findings for diagnosing DCM.
METHODS
One hundred twenty-one patients with DCM were enrolled. The Japanese Orthopaedic Association (JOA) score, radiological parameters, MRI and kinematic CT myelography (CTM) parameters, and the affected spinal level (according to multimodal spinal cord evoked potential examinations) were assessed. Kinematic CTM was conducted with neutral positioning or at maximal extension or flexion of the cervical spine. The cross-sectional area (CSA) of the spinal cord, dynamic change in the CSA, C2–7 range of motion, and C2–7 angle were measured. The associations between radiological parameters and hyperreflexia, the Hoffmann reflex, the Babinski sign, and positional sense were analyzed via multiple logistic regression analysis.
RESULTS
In univariate analyses, the upper- and lower-limb JOA scores were found to be significantly associated with a positive Hoffmann reflex and a positive Babinski sign, respectively. In the multivariate analysis, a positive Hoffmann reflex was associated with a higher MRI grade (p = 0.026, OR 2.23) and a responsible level other than C6–7 (p = 0.0017, OR 0.061). A small CSA during flexion was found to be significantly associated with a positive Babinski sign (p = 0.021, OR 0.90). The presence of ossification of the posterior longitudinal ligament (p = 0.0045, OR 0.31) and a larger C2–7 angle during flexion (p = 0.01, OR 0.89) were significantly associated with abnormal great toe proprioception (GTP).
CONCLUSIONS
This study found that the Hoffmann reflex is associated with chronic and severe spinal cord compression but not the dynamic factors. The Babinski sign is associated with severe spinal cord compression during neck flexion. The GTP is associated with large cervical lordosis. These imaging features can help us understand the characteristics of the neurological findings.
“…Recent studies have also highlighted the importance of internal, or subject-specific, factors on tissue-level biomechanics. These factors include the mechanical properties of the constituent tissues ( 10 , 21 , 26 – 29 ), and the transverse morphology of the spinal cord and canal of the individual subject (such as the cord mediolateral and dorsoventral diameter ( 3 , 22 ), and the thickness of CSF surrounding the spinal cord ( 30 )).…”
Section: Biomechanics Of Contusion Models Of Scimentioning
Large animal contusion models of spinal cord injury are an essential precursor to developing and evaluating treatment options for human spinal cord injury. Reducing variability in these experiments has been a recent focus as it increases the sensitivity with which treatment effects can be detected while simultaneously decreasing the number of animals required in a study. Here, we conducted a detailed review to explore if head and neck positioning in a cervical contusion model of spinal cord injury could be a factor impacting the biomechanics of a spinal cord injury, and thus, the resulting outcomes. By reviewing existing literature, we found evidence that animal head/neck positioning affects the exposed level of the spinal cord, morphology of the spinal cord, tissue mechanics and as a result the biomechanics of a cervical spinal cord injury. We posited that neck position could be a hidden factor contributing to variability. Our results indicate that neck positioning is an important factor in studying biomechanics, and that reporting these values can improve inter-study consistency and comparability and that further work needs to be done to standardize positioning for cervical spinal cord contusion injury models.
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