Prognostic value of nerve ultrasonography: A prospective multicenter study on the natural history of chronic inflammatory neuropathies.

BACKGROUND AND OBJECTIVE Nerve ultrasound is a promising new tool in chronic inflammatory neuropathies. The aim of this study was to determine its prognostic value in a prospective multicenter cohort study including incident and prevalent patients with CIDP and MMN. METHODS We enrolled 126 patients with CIDP, and 72 with MMN; 71 were treatment-naive. Patients with chronic idiopathic axonal polyneuropathy (CIAP; n = 35) were considered as disease controls. Standardized neurological examination, questionnaires, and nerve ultrasonography were obtained at time of inclusion and 1-year follow-up. Nerve size development over time and correlation between nerve size and clinical outcome measures were determined using linear mixed effects models. RESULTS Nerve size development over time was heterogeneous. Only in MMN was there a correlation between C5 nerve root size and deterioration of grip strength (-1.3 kPa/mm2 (95% confidence interval [CI] -2.3 to -0.2). No other significant correlations between nerve size and clinical outcome measures were found. In MMN, presence of nerve enlargement at inclusion predicted deterioration of grip strength, and MMN patients with enlargement confined to the brachial plexus seemed to have more favorable outcomes. No other predictive effects of sonographic nerve size were found. CONCLUSIONS The present study indicates that the natural course of nerve size development in CIDP and MMN is heterogeneous, and that the prognostic value of sonographic nerve enlargement is limited. It had some predictive effect in patients with MMN. Further research in specific subgroups of chronic inflammatory neuropathy is necessary to determine the usefulness of nerve ultrasonography after the diagnostic phase.