Shear wave elastography as a marker of anisotropy in denervated muscle tissue

To assess the capability of shear wave elastography (SWE) to detect muscle denervation.

36 patients underwent electrodiagnostic studies (EDX) of the lower limbs and volunteered to undergo ultrasound examination of the Tibialis anterior (TA) and the Gastrocnemius medialis (GCM) muscles. A variable reflecting the level of anisotropy was created by calculating the difference between the longitudinal and transverse shear wave velocity (SWE-D).

In the TA muscles, SWE-D correlated negatively with the quantity of fibrillation potentials (FP) and the degree of interference pattern (IP) reduction (p = 0.032, r = -0.185 and p = 0.006, r = -0.236, respectively). In the GCM muscles, SWE-D only correlated with the amount of IP reduction among patients of normal weight (p = 0.030, r = -0.285). There was also a significant difference in the overall SWE-D values in the GCM muscles between patients of normal weight and obese patients (p = 0.007).

Loss of anisotropy caused by denervation of muscle tissue may be measured quantitatively by calculating the differences between longitudinal and transverse shear wave velocities. However, obesity seems to hinder the SWE-based assessment of muscle denervation.

Being able to measure anisotropy caused by denervation acts as a base for further development of SWE methods to evaluate neurogenic injury.