K. Ichihara et al., Gray matter of the bovine cervical spinal cord is mechanically more rigid and fragile than the white matter, J NEUROTRAU, 18(3), 2001, pp. 361-367
The gray matter of the cervical spinal cord has been thought to be equally
or less rigid than the white matter. Based on this assumption, various stud
ies have been conducted on the changes of stress distributions within the s
pinal cord under mechanical compression, although the mechanical properties
of the white and gray matters had not been fully elucidated. The present s
tudy measured the mechanical properties of the white and gray matter of bov
ine spinal cords. For both the white and gray matter, the stress-strain cur
ves had a nonlinear region, followed by a linear region, and then a region
where the stresses plateaued before failure. In the nonlinear region, stres
s was not significantly different between the gray and white matter samples
(strain similar to0-10 %), while stress and Young's modulus in the gray ma
tter was significantly higher than the white matter in the linear part of t
he curve. The gray matter ruptured at lower strains than the white matter.
These findings demonstrated the gray matter is more rigid and fragile than
the white matter, and the conventional assumption (i.e., the white matter i
s more rigid than the gray matter) is not correct. We then applied our data
to computer simulations using the finite element method, and confirmed tha
t simulations agreed with actual magnetic resonance imaging findings of the
spinal cord under compression. In future computer simulations, including f
inite element method using our data, changes in stress and strain within th
e cervical spinal cord under compression would be clarified in more detail,
and our findings would also help to elucidate the area which can easily re
ceive histologic damage or which could have hemodynamic disorders under mec
hanical compression, as well as severity and location of biochemical and mo
lecular biological changes.