This study used ultrasound/electrophysiology of predefined nerves to differentiate between Charcot-Marie Tooth hereditary neuropathy (CMT1) and chronic inflammatory demyelinating polyradiculoneuropathies (CIDP), multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor neuropathies (MADSAM) and healthy controls. Ultrasound pattern sum score (UPSS, sum of the amount of 12 predefined measurement points), homogeneity score (HS) and regional nerve enlargement index (RNEI) in ulnar, median, and tibial nerve were used for evaluation of morphology. Significant enlargement was shown in all neuropathies compared to the controls, (p<0.001), however the amount of enlargement as evaluated by the UPSS was most prominent in CMT compared to the others (median UPSS 18 vs. 11/8.5/5 in CIDP/MADSAM/MMN, p<0.001). Homogeneous enlargement was significantly more often seen in CMT (67%, HS 6 vs. 2-3 in immune-mediated PNP, p<0.001), while in CIDP the enlargement was regional, homogeneous or inhomogeneous with equal contribution. In MMN and MADSAM regional enlargement (48%/40%) next to normal segments (∼20%) predominated (RNEI in MMN=2, in MADSAM=1 vs. 0 in the others). CSAs were inversely correlated with motor conduction velocity. Ultrasound, quantified by UPSS, HS, and RNEI facilitates a reliable and reproducible differentiation of immunoneuropathies and hereditary neuropathies by the use of boundary values. SIGNIFICANCE: By the use of quantitative scores, ultrasound differentiation of demyelinating neuropathies is operationalized and ameliorated compared to CSA measurements only.
