The right median nerve is swollen at 0.26 sq cm. Note the loss/blurring of the polyfascicular pattern. A sagittal view of the median nerve through the carpal tunnel shows hypoechoic, fusiform thickening and loss of the normal fascicular pattern. Bowing of the flexor retinaculum in the absence of hyperaemia (not shown) or obvious space occupying lesion such as a patent median artery.
The left flexor retinaculum is bowed in the absence of hyperaemia (not shown) or obvious SOL. The changes are less severe than on the right. There is hypoechoic thickening of the median nerve proximally with flattening distally. The left median nerve is swollen at 0.2 sq cm and there is blurring of the polyfascicular pattern.
Again, changes are less severe than on the right. Unlike on the right, there is no bowing of the flexor retinaculum at the distal carpal tunnel. However, the median nerve is flattened, surface area is at the upper limit of acceptable or the lower limit of pathological at 0.15 sq cm and there is complete loss of the polyfascicular pattern.