The Complex Pathway of Conventional Investigations before the Diagnosis of Functional Motor Disorders

Background: Functional motor disorder (FMD) is a diagnosis of inclusion based on the presence of positive signs on clinical examination, and only a few tests are validated as biomarkers for FMD identification. Objectives: The aim of this study was to assess the relative frequency of different types of conventional instrumental investigations (such as magnetic resonance imaging/computed tomography [MRI/CT] scan, dopamine transporter single-photon emission computed tomography (DaT-SPECT), electroencephalography (EEG), neurophysiological tests, and other tests) in FMD patients before diagnosis and to identify the clinical and demographic features associated with their use. Methods: Data were obtained from the Italian Registry of Functional Motor Disorders, a multicenter initiative involving patients with a diagnosis of clinically definite FMD. Patients were consecutively enrolled at 25 Italian centers during 2 phases. Data collection initially took place between September 2018 and August 2019, and during phase 2, between January 2020 and December 2022. Results: Among the 853 patients included during the 2 phases of the registry, we identified 794 patients (93.1%) who underwent 1 or more categories of conventional investigations. Overall, conventional investigations were more likely to be performed in older FMD patients (Odds ratio [OR]: 1.02; P = 0.013). Interestingly, we found that more than one category of investigation was more likely to be performed in FMD patients presenting with weakness (OR: 1.85; P = 0.002) and with additional functional symptoms (OR: 1.54; P = 0.026). Conclusions: Our findings provide novel insights into the complex diagnostic process of FMD patients. This study highlights the need to identify reliable biomarkers that may help physicians diagnose FMD earlier and carefully select the most appropriate conventional investigations.