Ultrasonography of the peripheral nervous system in the early stage of Guillain‐Barré syndrome

Ultrasonography can be used to visualize peripheral nerve abnormalities in immune‐mediated neuropathies. The objective of this study was to prove the role of ultrasonography (US) in acute phase of Guillain‐Barré syndrome (GBS). Systematic ultrasonic measurements of several peripheral nerves including the vagal nerve as well as the sixth cervical nerve root were performed in 18 patients with GBS at days 1–3 after symptom onset and compared to 21 healthy controls. Nerve conduction studies (NCS) of corresponding nerves were undertaken. Consequently, significant differences between the groups were found in compound muscle action potential amplitudes, F‐wave latency, and persistency. Ultrasonic cross‐sectional areas (CSAs) showed significant enlargement in all nerves except of the ulnar nerve (upper arm) and the sural nerve compared to healthy controls, most prominent in proximal and middle median nerve (p < 0.01). The vagal nerve also showed enlargement compared to controls (p < 0.05), which was most pronounced in patients with autonomic dysfunction compared to patients without (p < 0.05). C6 root diameter showed a significant correlation to the amount of cerebrospinal fluid (CSF)‐protein (Pearson correlation, p < 0.05). US shows nerve enlargement in several peripheral nerves including vagal nerve and C6 root in acute phase of GBS and could be an additional diagnostic tool for example, in GBS of atypical onset and autonomic dysfunction.