Fig. 1

Representative nerve-ultrasound results from two case studies. The white bordered areas display the perimeter measurement of the nerves used for CSA calculation. Diameter measurements of the described nerves are marked by the straight white lines. Patient 1: NMUS showed an increase of cross-sectional area (CSA) of the median nerve at the forearm of 13.4 mm² (a) and the dorsal roots C5 (upper diameter, 5.1 mm) and C6 (lower diameter, 4.4 mm) (b) at first presentation. After 2 months of therapy discontinuation, a significant reduction of CSA was visible in dorsal root C6 (d), which was consistent with a relevant clinical response of motor function and normalization of cranial nerves. After 5 months, the cross-sectional area of the median nerve (c) decreased from 13.4 to 8.4 mm². Patient 2: NMUS showed nerve swelling of the vagus nerve with a CSA of 3.6mm² (e), the increased diameter of the nerve roots C5 (3.78 mm) (f) and C6 (5.1 mm) (h) as well as the fibular nerve with an increased CSA of 11.6mm² (g) at the onset of diffuse CNS and PNS symptoms only a few days after the 1st cycle of durvalumab. Abbreviations: UA upper arm