Marieke van Rosmalen

Chapter 3 44 ABSTRACT Objective: Magnetic resonance imaging (MRI) of the brachial plexus shows nerve thickening in approximately half of the patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). The reliability of qualitative evaluation of brachial plexus MRI has not been studied previously. Methods: We performed an interrater study in a retrospective cohort of 19 patients with CIDP, 17 patients with MMN and 14 controls. The aim was to assess inter-rater variability between radiologists using a predefined scoring system that allowed the distinction of no, possible or definite nerve thickening. Results: Raters agreed in 26 of 50 (52%) of all brachial plexus images. Kappa coefficient was 0.30 (SE 0.08, 95% CI 0.14 – 0.46, p < 0.0005). Conclusion: Our results indicate that inter-rater reliability of qualitative evaluation of brachial plexus MRI is low. Objective criteria for abnormality are needed to optimize the diagnostic value of MRI for inflammatory neuropathies.