Sabrina Lee, Ph.D.
Physical Therapy and Human Movement Sciences
ultrasound, nerve, shear wave velocity, SWV, stiffness, upper extremity, median, ulnar, radial, proximal, distal
Third Floor, Feinberg Pavilion, Northwestern Memorial Hospital
Shear wave ultrasound elastography is used to quantify mechanical properties, such as stiffness. As shear wave velocity (SWV) increases, stiffness increases. Preliminary data of patients with peripheral nerve injury suggest that: 1) nerves distal to the injury site have increased SWV, indicating increased stiffness and 2) nerves proximal to the injury are similar to non-injured nerves. However, little is known about the spatial dependence of nerve stiffness. The aim of our study was to spatially characterize mechanical properties, specifically stiffness, of nerves by measuring SWV in the median, ulnar, and radial nerves of healthy individuals. We measured SWV of these three nerves on the arms of 11 healthy individuals (7 males, 4 females, 26.0± 4.0 yrs, 177.7± 5.0 kg, and 1.8± .05 m) at the bicep (proximal location) and on the lower third of the forearm (distal location). We found SWV values to be greater at distal locations (radial = 5.41± 1.05 m/s, ulnar = 5.77± 1.55 m/s, median = 6.36± 0.76 m/s) (p < 0.05) than at proximal locations (radial = 3.93± 0.69 m/s, ulnar = 3.67± 0.95 m/s, median = 5.02± 1.39 m/s) (p < 0.05). These findings suggest that upper extremity nerves are naturally stiffer more distally than proximally.