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Viscoelasticity of spinal cord and meningeal tissues.
Acta Biomater 2018; 75:253-262AB

Abstract

Compared to the outer dura mater, the mechanical behavior of spinal pia and arachnoid meningeal layers has received very little attention in the literature. This is despite experimental evidence of their importance with respect to the overall spinal cord stiffness and recovery following compression. Accordingly, inclusion of the mechanical contribution of the pia and arachnoid maters would improve the predictive accuracy of finite element models of the spine, especially in the distribution of stresses and strain through the cord's cross-section. However, to-date, only linearly elastic moduli for what has been previously identified as spinal pia mater is available in the literature. This study is the first to quantitatively compare the viscoelastic behavior of isolated spinal pia-arachnoid-complex, neural tissue of the spinal cord parenchyma, and intact construct of the two. The results show that while it only makes up 5.5% of the overall cross-sectional area, the thin membranes of the innermost meninges significantly affect both the elastic and viscous response of the intact construct. Without the contribution of the pia and arachnoid maters, the spinal cord has very little inherent stiffness and experiences significant relaxation when strained. The ability of the fitted non-linear viscoelastic material models of each condition to predict independent data within experimental variability supports their implementation into future finite element computational studies of the spine.

STATEMENT OF SIGNIFICANCE

The neural tissue of the spinal cord is surrounded by three fibrous layers called meninges which are important in the behavior of the overall spinal-cord-meningeal construct. While the mechanical properties of the outermost layer have been reported, the pia mater and arachnoid mater have received considerably less attention. This study is the first to directly compare the behavior of the isolated neural tissue of the cord, the isolated pia-arachnoid complex, and the construct of these individual components. The results show that, despite being very thin, the inner meninges significantly affect the elastic and time-dependent response of the spinal cord, which may have important implications for studies of spinal cord injury.

Authors+Show Affiliations

School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA.Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA.School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA; Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA; Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA. Electronic address: puttlitz@engr.colostate.edu.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29852238

Citation

Ramo, Nicole L., et al. "Viscoelasticity of Spinal Cord and Meningeal Tissues." Acta Biomaterialia, vol. 75, 2018, pp. 253-262.
Ramo NL, Troyer KL, Puttlitz CM. Viscoelasticity of spinal cord and meningeal tissues. Acta Biomater. 2018;75:253-262.
Ramo, N. L., Troyer, K. L., & Puttlitz, C. M. (2018). Viscoelasticity of spinal cord and meningeal tissues. Acta Biomaterialia, 75, pp. 253-262. doi:10.1016/j.actbio.2018.05.045.
Ramo NL, Troyer KL, Puttlitz CM. Viscoelasticity of Spinal Cord and Meningeal Tissues. Acta Biomater. 2018 07 15;75:253-262. PubMed PMID: 29852238.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Viscoelasticity of spinal cord and meningeal tissues. AU - Ramo,Nicole L, AU - Troyer,Kevin L, AU - Puttlitz,Christian M, Y1 - 2018/05/28/ PY - 2018/03/18/received PY - 2018/05/02/revised PY - 2018/05/25/accepted PY - 2018/6/1/pubmed PY - 2019/6/14/medline PY - 2018/6/1/entrez KW - Constitutive modeling KW - Mechanical characterization KW - Pia mater KW - Spinal cord KW - Viscoelasticity SP - 253 EP - 262 JF - Acta biomaterialia JO - Acta Biomater VL - 75 N2 - : Compared to the outer dura mater, the mechanical behavior of spinal pia and arachnoid meningeal layers has received very little attention in the literature. This is despite experimental evidence of their importance with respect to the overall spinal cord stiffness and recovery following compression. Accordingly, inclusion of the mechanical contribution of the pia and arachnoid maters would improve the predictive accuracy of finite element models of the spine, especially in the distribution of stresses and strain through the cord's cross-section. However, to-date, only linearly elastic moduli for what has been previously identified as spinal pia mater is available in the literature. This study is the first to quantitatively compare the viscoelastic behavior of isolated spinal pia-arachnoid-complex, neural tissue of the spinal cord parenchyma, and intact construct of the two. The results show that while it only makes up 5.5% of the overall cross-sectional area, the thin membranes of the innermost meninges significantly affect both the elastic and viscous response of the intact construct. Without the contribution of the pia and arachnoid maters, the spinal cord has very little inherent stiffness and experiences significant relaxation when strained. The ability of the fitted non-linear viscoelastic material models of each condition to predict independent data within experimental variability supports their implementation into future finite element computational studies of the spine. STATEMENT OF SIGNIFICANCE: The neural tissue of the spinal cord is surrounded by three fibrous layers called meninges which are important in the behavior of the overall spinal-cord-meningeal construct. While the mechanical properties of the outermost layer have been reported, the pia mater and arachnoid mater have received considerably less attention. This study is the first to directly compare the behavior of the isolated neural tissue of the cord, the isolated pia-arachnoid complex, and the construct of these individual components. The results show that, despite being very thin, the inner meninges significantly affect the elastic and time-dependent response of the spinal cord, which may have important implications for studies of spinal cord injury. SN - 1878-7568 UR - https://www.unboundmedicine.com/medline/citation/29852238/Viscoelasticity_of_spinal_cord_and_meningeal_tissues_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1742-7061(18)30322-2 DB - PRIME DP - Unbound Medicine ER -