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

Sonography of Carpal Tunnel Syndrome According to Pathophysiologic Type: Conduction Block Versus Axonal Degeneration

“…Our results are also consistent with a few previous reports describing sonographic findings and their correlations with pathophysiologic types . Several studies have reported that axonal nerve lesions lead to greater nerve swelling than demyelinating lesions do . One study reported a correlation between sonographic and electrophysiologic findings in patients with common fibular neuropathy at the fibular head and found that axonal damage was frequently accompanied by an increase in the cross‐sectional area …”

“…A few previous studies have evaluated sonographic findings in nerves and their relationships with pathophysiologic types, as assessed electrophysiologically. Among the studies comparing electrophysiologic and sonographic data in patients with ulnar neuropathy at the elbow, several have reported that axonal nerve lesions lead to greater nerve swelling than demyelinating lesions do . One study reported a correlation between sonographic and neurophysiologic findings in patients with common fibular neuropathies at the fibular head, where axonal damage was frequently accompanied by an increase in the cross‐sectional area .…”

Neuromuscular ultrasound in electrically non‐localizable ulnar neuropathy

“…As abnormal but non‐localizing ulnar electrophysiology denotes axonal loss more than demyelination, our study is also in agreement with several studies of UNE in which the ulnar CSA was greatest in patients with axonal loss physiology …”

Carpal tunnel syndrome in advanced age: A sonographic and electrodiagnostic study

“…The usual response to peripheral nerve compression in experimental animal studies involves a cascade of events that include “endoneurial edema, demyelination, inflammation, distal axonal degeneration, fibrosis, growth of new axons, remyelination, and thickening of the perineurium and endothelium.” Resected nerve segments from patients with advanced stages of compression show “thickening of the walls of the microvessels in the endoneurium and perineurium as well as epineurial and perineurial edema, thickening, and fibrosis at the site of the injury.” It is likely that the enlarged median nerve CSA in patients with CTS reflects the morphological changes associated with these biological events, particularly edema and fibrosis, leading to nerve thickening. Animal models of nerve compression have also shown that the degree of axonal degeneration is associated with the amount of endoneurial edema, which again is consistent with the ultrasound finding in our younger population with CTS and in previous studies of compressive mononeuropathy that suggests a positive relationship between nerve CSA and disease severity …”