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. Muscle Nerve 55: 213-222, 2017.