Neuropsychiatric phenotypes in functional movement disorder.

OBJECTIVE: Functional movement disorder (FMD), the motor-dominant subtype of functional neurological disorder, is a complex neuropsychiatric condition. Patients with FMD also manifest non-motor symptoms. Given that patients with FMD are diagnosed based on motor phenotype, the contribution of non-motor features to the neuropsychiatric syndrome is not well characterized. The objective of this hypothesis-generating study was to explore potential novel, neuropsychiatric FMD phenotypes by combining movement disorder presentations with non-motor comorbidities including somatic symptoms, psychiatric diagnoses, and psychological traits. METHODS: This retrospective chart review evaluated 158 consecutive patients with a diagnosis of FMD who underwent deep phenotyping across neurological and psychiatric domains. Demographic, clinical, and self-report features were analyzed. A data-driven approach using cluster analysis was performed to detect patterns when combining the movement disorder presentation with somatic symptoms, psychiatric diagnoses, and psychological factors. These new neuropsychiatric FMD phenotypes were then tested using logistic regression models. RESULTS: Distinct neuropsychiatric FMD phenotypes emerged when stratifying by episodic vs. constant motor symptoms. Episodic FMD was associated with hyperkinetic movements, hyperarousal, anxiety, and history of trauma. In contrast, constant FMD was associated with weakness, gait disorders, fixed dystonia, activity avoidance, and low self-agency. Pain, fatigue, somatic preoccupation, and health anxiety were common across all phenotypes. CONCLUSION: This study found patterns spanning the neurological-psychiatric interface that indicate that FMD is part of a broader neuropsychiatric syndrome. Adopting a transdisciplinary view of illness reveals readily identifiable clinical factors that are relevant for the development and maintenance of FMD.

Factors Influencing Triage to Rehabilitation in Functional Movement Disorder.

BACKGROUND: Treatment of functional movement disorder (FMD) should be individualized, yet factors determining rehabilitation engagement have not been evaluated. Subspecialty FMD clinics are uniquely poised to explore factors influencing treatment suitability and triage. OBJECTIVES: To describe our approach and explore factors associated with triage to FMD rehabilitation. METHODS: We conducted a retrospective chart review of 158 consecutive patients with FMD seen for integrated assessment by movement disorders neurology and psychiatry, with the purpose of triage to rehabilitation. Demographic and clinical variables were compared between patients triaged to therapy versus no therapy, and logistic regression was used to explore factors predictive of triage outcome. Change in primary outcome scores were analyzed. RESULTS: Sixty-six patients (42%) were triaged to FMD therapy from July 2019 to December 2021. Patients triaged to therapy were more likely to have a constant movement disorder, gait disorder and/or tremor, hyperarousal, readiness for change, and people pleasing traits. Patients triaged to no therapy demonstrated persistent diagnostic disagreement, an inability to appreciate motor symptom inconsistency, low self-agency, a propensity to dissociate, and cluster B traits. 90% of patients triaged to rehabilitation had improved outcomes. CONCLUSIONS: The ability to "opt-in" to FMD rehabilitation relies on different factors than those relevant to establishing a diagnosis. Unlike many other neurological disorders, a triage and treatment planning step is recommended to identify those likely to meaningfully engage at that time. Holistic assessment through a transdisciplinary lens, and working collaboratively with the patient is essential to prioritize symptoms, determine engagement, and identify treatment targets.