Résumé
Lately, evidence of modifications in resting brain metabolism have been demonstrated in patients experiencing a first episode of motor functional neurological disorder. The aim of this study is to investigate the association between the level of peripheral inflammation markers, the markers of axonal integrity measured in blood and the course of both symptoms and brain metabolism in patients with motor functional neurological disorder. Methods: for this ancillary study, we used blood samples and 18-FDG PET brain metabolism data from the NCT02329626 prospective pilot study conducted from January 2016 to July 2017. We thawed the blood samples to measure neuronal integrity markers (neurofilaments light chain) and a panel of cytokines in the serum of 17 patients with motor functional neurological disorder. We compared the levels of these markers at inclusion with those measured in a population of depressed individuals (affective controls). The biological data were then correlated to the clinical data and to the brain metabolism measured with 18-FDG PET at inclusion and 3 months to follow-up. Results: at baseline, there were significantly higher concentration of TNF-α (p < 0,0001), CCL2 (p < 0,0001), IL-1ra (p < 0,0001), IL-6 (p < 0,01) and IFN-γ (p < 0,01) in patient with functional neurological disorder compared with the affective control. Conclusion: our data suggest existence of low-grade inflammation associated with functional neurological disorder in the acute phase. The increase in the rate of neurofilament and their correlation with brain metabolism in regions considered as state markers could be a witness of microscopic axonal lesions over disease course.