You can keep up with all your speculations, as long as you cite studies with no control group or mathematical model, that's all it is: speculation
Im not an expert on this type of mathematical modelling but there are certainly branches of science involving systems perhaps even more complex than the human body, where we take modelling quite seriously , like climate science. So I don't think it's fair to say that modelling is only speculation.
I think the discussion of background and metrics is interesting.
"Kubota demonstrated that a clivo-axial angle of less than 130° was associated with delay or failure to recover after foramen magnum decompression.[
18] Numerous series of patients report cervicomedullary kyphosis or ventral flattening in the presence of a kyphotic clivo-axial angle or retroflexed odontoid process.[
2,
5,
6,
16] Medullary kinking and basilar invagination introduce abnormal deformative stresses in the brainstem and spinal cord,[
19–
23] which result in neurobiological changes that are believed to underlie the pathophysiology of many of the observed neurological changes in this group of patients.[
12–
15,
22–
32]
In a novel approach, the authors applied a finite element analysis (FEA) research tool to compute estimates of preoperative and postoperative mechanical stress within the brainstem and spinal cord in 5 children with medullary kinking due to kyphotic clivo-axial angulation in the context of Chiari malformation or basilar invagination. These stresses were compared with clinical metrics.
Finite element analysis is a mathematical method that reduces a continuous structure into discrete finite brick elements. This method allows the approximation of partial differential equations with a linear system of ordinary differential equations, which can then be solved by numerical methods with the appropriate boundary conditions. In this particular case, the equations concern mechanical strain, out-of-plane loading and material properties such as Young’s modulus of elasticity or Poisson’s ratio.
A model of the brainstem and spinal cord that incorporates patient-specific anatomical data such as deformity over the odontoid process, lengthening of brainstem and spinal cord with flexion, and numerous other features such as compression of the spinal cord by a herniated disc or spur has been developed to parametrically generate specific finite element models for each patient. The computations derived from these models undergoing flexion and extension generate estimates of the stresses existing within the brainstem and spinal cord in the neutral, flexion and extension conditions. The estimated stresses reflect the dynamic change in stress exerted on the neural tissue. The importance of biomechanical stress has recently been demonstrated in the neurobiological, clinical, experimental and biomechanical literature.
The FEA estimations of deformative strain, generated postoperatively, were used to test the hypothesis that reduction of abnormal stresses improved neurological deficits. The 5 patients studied herein underwent open reduction (normalization of the clivo-axial angle) and posterior translation to normalize the craniospinal relationship. This reduction was followed by occipitocervical fusion and stabilization.[
1,
7,
16] Correlation of computed mechanical stresses with clinical outcome indices suggested a direct relationship between reduction of deformative stress and clinical improvement....
An FEA program (PRIMEGen) was adapted for the purpose of modeling the brainstem and cervical and upper thoracic spinal cord under dynamic loading and strain. The resulting Spinal Cord Stress Injury Analysis (SCOSIA©) technology computes probable magnitude and location of stress within the brainstem and upper spinal cord. The Von Mises stress is the aggregate of both in-line strain, or stretching; and the stress due to “out-of-plane loading,” such as from odontoid compression.
Computer-driven stress analysis–based finite element formulations provide a unique perspective on the biomechanical behavior of the human cervical spine under normal, degenerative and iatrogenically surgically altered conditions. Due to the reproducibility and repeatability of finite element models, detailed parametric analysis with regards to the geometrical conditions and material property changes can be performed, and biomechanical responses can be evaluated using FEA. FEA is routinely used to study spine mechanics.[
37–
47] More recently, FEA has been applied to spinal disorders[
48] and spinal cord pathologies.[
20,
21,
49]
Due to the displacement-based formulation of structural finite elements, nodal displacements are primary output variables and nodal stresses are computed variables using nodal displacements. In other words, stresses are predicted based upon the deformation or stretching of specific nodes, with specific Cartesian coordinates within the system."
As for no study with a control group, I did fins a Milhorat/Bolognese study on measurements supine vs upright which had a healthy control group as well as a group with only chiari and no ctd, posted in other thread , i couldn't upload the PDF from scihub but it's there, if anyone cares to read full text.
https://thejns.org/spine/view/journals/j-neurosurg-spine/7/6/article-p601.xml
Just take the doi from this study and put it into scihub
I do think it's possible that the mathematical modelling is very relevant to this discussion, but I don't know much about it. I know there must be someone on this board who's an engineer or understands the physics that might understand it.
