PMC10225816_01
NUS, MRI, and 18F-FDG PET/CT findings. A: NUS of the right median nerve shows marked enlargement (CSA: 54 mm2) at the forearm, 7 cm proximal from the wrist in short-axis and longitudinal views (thin arrows). The nerve fascicles and perineurium are swollen, resulting in irregular fascicular patterns. A fusiform hypoechoic mass (triangles) is observed between the nerve and thickened epineurium (arrowheads). B: NUS shows massive enlargements of the supraclavicular region of the brachial plexus (dotted frame) (167 mm2). Color Doppler imaging depicts increased epineural and perineural vascularity. C: A Dixon sequence of MRI shows the enlarged right median nerve with a short-axis view. The nerve is surrounded by the thickened epineurium, consistent with the NUS findings (white arrow). D: Massive enlargement of the right nerve roots and brachial plexus is seen in MRI with a STIR sequence (open arrow). E: 18F-FDG PET/CT shows an abnormal FDG uptake in the right median nerve (white arrows), nerve roots, and brachial plexus (open arrows), corresponding to the abnormal findings in the NUS and MRI. The right axillary lymph node also shows abnormal uptake (arrowhead). * Normal values for CSA at our laboratory for the evaluated sections: the median nerve (wrist), 8 mm2; the brachial plexus, 45 mm2. CSA, cross-sectional area; MRI, magnetic resonance imaging; NUS, nerve ultrasound; SCA, subclavian artery; 18F-FDG PET/CT, fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography.
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Additionally, a fusiform hypoechoic mass was observed between the nerve and the thickened epineurium (Fig. 1A, Supplementary Video 1). Supplementary Video 2). Subsequent MRI revealed massive swelling of the right median nerve, nerve roots, and brachial plexus, consistent with the NUS findings, and these structures showed abnormal FDG uptake on 18F-FDG PET/CT, suggesting NL (Fig. 1D-F).
Sequential NUS assessments. The CSA of the right median nerve at the forearm and the brachial plexus (supraclavicular region) shows a remarkable decrease after two courses of chemotherapy (54 mm2 to 16 mm2 and 167 mm2 to 63 mm2, respectively). CSA, cross-sectional area; SCA, subclavian artery.
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NCS were still absent, suggesting severe axonal loss and poor functional outcome (Table 1, Post-chemotherapy). Nevertheless, in the NUS, the enlargement of the nerves, brachial plexus, and nerve roots had dramatically subsided, demonstrating the effectiveness of chemotherapy (Fig. 2).