Ultrasonography of ulnar neuropathy at the elbow: Axonal involvement leads to greater nerve swelling than demyelinating nerve lesion

► High-resolution ultrasound shows pronounced focal morphological abnormalities of the ulnar nerve at the elbow in UNE, which may be of significant diagnostic help particularly in nerve lesions with non-localizing axonal loss. ► Nerve size parameters, such as the largest cross sectional area (CSAmax) of the ulnar nerve around the elbow and the cubital-to-humeral nerve area ratio (CHR) show significantly larger nerve swelling in axonal lesions, as compared to predominantly demyelinating lesions. ► The subtype of axonal lesion also affects nerve size parameters: CSAmax values in patients with sensorimotor axonal lesion were significantly higher than in those with pure sensory axonal involvement.