Abstract
Objective
Functional motor disorders (FMDs) are disabling neurological conditions characterized by abnormal movements which are inconsistent and incongruent with recognized neurological diseases. Aim of this study is to investigate whether FMDs are related to structural axonal damage.
Methods
Consecutive patients with a definite diagnosis of FMD with no other neurological/psychiatric comorbidities (pure FMDs) and age-matched healthy controls (HCs) were recruited in a tertiary center and demographic/clinical data were collected. Serum neurofilament light chain (NfL) assessment was performed with ultrasensitive paramagnetic bead-based enzyme-linked immunosorbent assay.
Results
34 patients with FMDs and 34 HCs were included. NfL levels were similar (p = 0.135) in FMDs (median 8.3 pg/mL, range 2–33.7) and HCs (median 6.1 pg/mL, range 2.7–15.6). The area under curve (0.606, 95% CI 0.468–0.743) confirmed that NfL concentration was not different in the two groups. NfL values were similar in patients with paroxysmal vs persistent disease course (p = 0.301), and isolated vs combined symptoms (p = 0.537). NfL levels were associated with age (p < 0.0001), but not with disease duration (p = 0.425), number of CNS acting drugs (p = 0.850), or clinical features (p = 0.983).
Discussion
Our preliminary data show that NfL levels are similar in patients with FMDs and HCs, indicating the lack of neuroaxonal damage. These results have relevant pathogenic and clinical implications and suggest that serum NfL may be a promising diagnostic biomarker, potentially useful to differentiate functional vs structural neurological disorders.
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Data Availability Statement
Data are available for sharing and further examination from the corresponding authors on reasonable request. The data are not publicly available because they contain information that could compromise patients’ privacy.
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Dinoto, A., Marcuzzo, E., Chiodega, V. et al. Neurofilament light chain: a promising diagnostic biomarker for functional motor disorders. J Neurol 270, 1754–1758 (2023). https://doi.org/10.1007/s00415-022-11480-6
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DOI: https://doi.org/10.1007/s00415-022-11480-6