Clinical features of adolescent-onset functional motor disorders in tertiary movement disorders centers

Background: Functional Motor Disorders (FMDs) represent a diagnostic and therapeutic challenge in pediatric neurology, particularly among adolescents. Their clinical presentation is common but often nonspecific, leading to frequent misdiagnoses and diagnostic delays. We aimed to characterize FMDs in adolescents and to examine the frequency of isolated and combined phenotypes and their associations with demographic and clinical variables. Methods: In this observational study, data were obtained from the Italian Registry of FMDs, including patients with a clinically definite diagnosis of FMD consecutively enrolled at 25 Italian tertiary movement disorders centers. Results: Among 847 patients, 93 (10.9%) had adolescent-onset FMDs. Motor phenotypes did not differ significantly between adolescent- and adult-onset FMDs, with the exception of parkinsonism, which was observed only in the latter. Compared with adult-onset FMDs, adolescent-onset FMDs were associated with a longer disease duration, a higher number of medical consultations before diagnosis, and a higher frequency of functional seizures and infections, but with lower rates of insomnia, fatigue, and antipsychotic use. In multivariable analysis, adolescent-onset FMDs remained independently associated with a greater number of medical consultations (adjusted OR 1.07; 95% CI 1.02–1.13), the presence of functional seizures (adjusted OR 2.06; 95% CI 1.09–3.8), and with lower occurrence of insomnia (adjusted OR 0.49; 95% CI 0.27–0.92) and fatigue (adjusted OR 0.51; 95% CI 0.30–0.86). Pain was more likely to be associated with the combined FMDs phenotype. Conclusions: Adolescent-onset FMDs are common and are associated with several non-motor symptoms in tertiary movement disorders centers. Early and accurate diagnosis may help to reduce unnecessary investigations and inappropriate treatments.