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Mechanical functioning of peripheral nerves: linkage with the "mushrooming" effect
Erik T Walbeehm1, Andrew Afoke, Thijs de Wit
1Department of Plastic and Reconstructive Surgery, UHR Dijkzigt and Erasmus University, Rotterdam, The Netherlands. erikwalbeehm@mac.com
Cell and Tissue Research
|February 27, 2004
Summary
Nerve biomechanics are influenced by the interplay between internal swelling pressure and external sheath restraint. Damage to nerve integrity significantly impairs its mechanical properties and strength.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Materials Science
Background:
- Nerve biomechanical properties are extensively studied, with neural matrix tissues considered primary load-bearing components.
- The epineurium's architecture may allow nerve extensibility, while the perineurium might resist endoneurial pressure.
Purpose of the Study:
- To investigate the hypothesis that nerve mechanical behavior depends on the interaction between core swelling pressure and outer sheath restraint.
- To determine the effects of altered nerve integrity on biomechanical properties.
Main Methods:
- Rat sciatic nerves were subjected to mechanical loading in vivo and ex vivo.
- Nerve segment retraction was measured post-excision and after incubation or freezing.
- Nerve swelling properties were assessed using water or phosphate buffer solution (PBS) with intact or opened epineurium.
Main Results:
- Excision led to a significant decrease in nerve strength and stiffness compared to in vivo conditions, with an average retraction of 11%.
- Freezing or incubation did not significantly alter nerve retraction.
- Nerve swelling properties differed significantly between intact and opened epineurium, suggesting the epineurium acts as a constraint and nerves are underhydrated.
Conclusions:
- The intact nerve model involves a connective tissue tube (epineurium) constraining internal neural core swelling pressure.
- Loss of nerve integrity detrimentally affects its biomechanical properties, highlighting the importance of this structural balance.