Posture-induced changes in peripheral nerve stiffness measured by ultrasound shear-wave elastography

Introduction: Peripheral nerves slide and stretch during limb movements. Changes in nerve stiffness associated with such movements have not been examined in detail but may be important in understanding movement-evoked pain in patients with a variety of different musculoskeletal conditions. Methods: Shear-wave elastography was used to examine stiffness in the median and tibial nerves of healthy individuals during postures used clinically to stretch these nerves. Results: Shear-wave velocity increased when limbs were moved into postures that are thought to increase nerve stiffness (mean increase: median nerve = 208% in arm, 236% in forearm; tibial nerve = 136%). There was a trend toward a negative correlation between age and shear-wave velocity (r = 0.58 for tibial nerve). Conclusions: Shear-wave elastography provides a tool for examining nerve biomechanics in healthy individuals and patients. However, limb position, age, and effects of nerve tension on neural architecture should be taken into consideration.