In vitro and in vivo mechanical properties of human ulnar and median nerves

Abstract

Peripheral nerves are often subjected to mechanical stretching, which in excess results in various degrees of impairment of their function. An understanding of the biomechanical behavior of peripheral nerves is important to the prevention of nerve injury during surgical manipulation. Here, in vitro mechanical properties and viscoelastic behavior of human ulnar/median nerves were measured with a tensile tester. In vivo stress and deformation of an ulnar nerve was also examined in continuity during a surgical procedure. Finite element models were developed to determine in vitro and in vivo viscoelastic parameters of the nerves. The results show that in vitro mechanical properties of fresh ulnar nerve are different from those measured in vivo. Several factors that are possibly attributed to the difference were analyzed. The in situ strain of the nerves is one of the major factors that must be considered to obtain accurate strain-stress relationship in the in vivo measurement.

Detecting Median Nerve Strain Changes with Cyclic Compression Apparatus: A Comparison of Carpal Tunnel Syndrome Patients and Healthy Controls

“…On the basis of the results of this study, there is a need to define the normal strains of age-specific groups. Third, we did not confirm our findings by alternative methods, such as magnetic resonance elastography (McCullough et al 2011) or other strain measurement methods (Ma et al 2013). However, there is still no gold standard for the measurement of peripheral nerve strain both in vivo and in vitro.…”

Towards viscoelastic characterisation of the human ulnar nerve: An early assessment using embalmed cadavers

“…Human peripheral nerves are known to exhibit viscoelastic properties [16] and this has been demonstrated for the human ulnar nerve by performing in vitro stress relaxation tests [17].…”

Differences in the Microstructure and Biomechanical Properties of the Recurrent Laryngeal Nerve as a Function of Age and Location

“…Other research groups have performed studies on the mechani cal behavior and/or the microstructure of other peripheral nerves including but not limited to the ulnar nerve, tibial nerve, median nerve, and sciatic nerve [32,[42][43][44][45][46][47][48][49], Ma et al published a study of adult human cadaver ulnar nerves stretched at a rate of 0.05 mm/s up to 10% strain found an average maximum value of tensile stress to be 0.18 MPa which is lower on average than the stresses we have calculated in the porcine RLN [43], In another study of the sciatic nerve of female guinea pigs, Young's Modulus was reported at 5%, 10%, 15%, and 20% strain, being 32 MPa (±13) at 15% which is the maximum stretch we achieved in our study [46]. This is higher than the values we reported which may be due to differences in species and/or differences in the amount of force imposed on the sciatic nerve than the RLN.…”