Semiquantitative assessment of preganglionic nerves for chronic immune-mediated neuropathies using brachial plexus magnetic resonance imaging.

BACKGROUND: Brachial plexus magnetic resonance imaging (MRI) is an important noninvasive supplementary diagnostic method of chronic immune peripheral neuropathies, but few MRI studies on the preganglionic nerves have been conducted. This retrospective cross-sectional study aimed to establish a reliable assessment for brachial plexus preganglionic nerve thickness and to use this method to assess and compare nerve characteristics in various types of peripheral neuropathies.

METHODS: Hospitalized patients diagnosed as positive for anti-neurofascin-155 (NF155)-positive autoimmune nodopathy (AN) (NF155+ ), chronic inflammatory demyelinating polyneuropathy (CIDP), or multifocal motor neuropathy (MMN) at Huashan Hospital of Fudan University in Shanghai, China, who underwent brachial plexus MRI between October 2011 and August 2023 were consecutively recruited for this study. We also recruited participants who underwent brachial plexus MRI during this period with no history of trauma, inflammation, tumors, compression, or degenerative conditions as healthy controls. According to our self-developed semiquantitative assessment of preganglionic nerves, we assessed the bilateral preganglionic C5-C8 nerves individually and scored the enlargement degree from 0 to 4 points. Furthermore, a sum score ≥20 was defined as definite enlargement.

RESULTS: A total of 122 participants were enrolled, including 28 with NF155+ , 40 with CIDP, 15 with MMN, and 39 healthy controls. In the comparison of the single-nerve scores, we found that there was a significant difference distribution among the four groups (χ2 test; P<0.001), with the patients with NF155+ exhibiting the highest scores in each of the bilateral C5-C8 nerves. In the comparison of the sum scores, a descending tendency was observed in patients NF155+ , CIDP, and MMN, with median scores of 11, 4, and 0 points, respectively (Kruskal-Wallis test; P=0.003, P<0.001, and P=0.005, respectively for NF155+ vs . CIDP, NF155+ vs . MMN, and CIDP vs . MMN). The proportion of definite enlargement in those with NF155+ was greater than that in healthy controls (21% vs . 0%; χ2 test; P=0.004), and the sum score at 0 points was lower in the NF155+ group than in CIDP, MMN, and healthy control groups (7% vs . 37%, 87%, and 41%, respectively; χ2 test; P<0.001).

CONCLUSIONS: This semiquantitative assessment can be a valuable tool for measuring preganglionic nerve enlargement, which was found to be decreased, respectively, in those with NF155+ , CIDP, and MMN. Presence of definite enlargement could be a strong indicator of NF155+ in clinic.