Differentiation of Guillain-Barré syndrome (GBS) and acute-onset chronic inflammatory demyelinating polyradiculoneuritis (CIDP) might be intricate in early stages. We compared electrodiagnostics (EDx) and nerve ultrasound (NUS) as tools for early distinction and follow-up. NUS and EDx have been performed at first visitation and after 6 months. The nerve conduction study score (NCSS), the ultrasound pattern sum score (UPSS), and clinical scores were used for comparison. Compared with the 33 GBS patients, the 34 CIDP patients (50% with symptoms < 4 weeks) revealed significant nerve enlargement in ultrasound (p < 0.001) except for the roots and vagus, which exhibited increased values in both groups. EDx has no significant differences between both groups except for the A-wave frequency and the sural sparing pattern, which is more frequent in GBS (Fisher's exact p < 0.05). In the latter, particularly, pure sensory nerves were not enlarged in contrast to CIDP, in which those were mostly enlarged (p < 0.001). This ultrasonic sensory sparing pattern (uSSP) in combination with enlarged roots/vagus is the hallmark finding in GBS with sensitivity, specificity, and positive predictive value > 85%, whereas in CIDP, enlarged sensory und multifocally enlarged sensorimotor nerves are key differentiation features to GBS. Increased echointensity of the nerves further arises only in CIDP. After 6 months, in CIDP, the significant nerve enlargement persisted, whereas in GBS, all segments almost normalized. Clinical, ultrasonic, and NCS scores correlated significantly over the time. Enlarged roots/vagus in combination with uSSP might facilitate differentiation of GBS and CIDP in the early stage, and ultrasonic 6-month normalization underlines the diagnosis of GBS in cases of uncertainty. Trial Registration: DRKS-ID 00005253.
Keywords: CIDP; GBS; UPSS; high-resolution ultrasound; immune-mediated neuropathies.