Median nerve deformability, mobility altered in patients with CTS

Patients with carpal tunnel syndrome (CTS) differ from normal subjects in terms of mobility and deformability of the median nerve, according to a study published in the April issue of Academic Radiology.

CTS is known to affect the motion of the wrist and fingers in patients, yet literature that quantitatively compares median nerve motion and deformation during wrist motion in patients with CTS and controls is lacking. Lead author Yuexiang Wang, MD, of the Mayo Clinic in Rochester, Minn., and colleagues examined the cross-sectional plane of the median nerve to establish deformation and mobility during six different hand and wrist motions in 13 patients with CTS. These results were then compared to the results reported for 10 healthy subjects in a previous study.

Defining the deformation ratio for each movement as the median nerve area, perimeter and circularity of the final position, the researchers found that the deformation ratio for circularity was significantly less in patients with CTS during wrist flexion.

Additionally, the mean vector of median nerve displacement during wrist flexion significantly varied between patients with CTS and healthy subjects. The displacement magnitude of the median nerve was less in patients with CTS compared to the healthy subjects during all movements except wrist extension with fingers extended.

“This study has revealed differences in median nerve transverse kinematics in the carpal tunnel between patients with CTS and healthy subjects,” wrote Wang and colleagues. “Further studies with a larger sample of patients are necessary to determine if changes of kinematics of the median nerve can be related to severity of CTS and whether these measurements may be usefulness for predicting treatment response,” they concluded.