A Scoping Review of Measures Used to Assess Stress-Related Motor Dysfunction in Functional Movement Disorder.

Abstract

Functional Neurological Disorder (FND) is a complex condition characterized by a range of motor and non-motor symptoms, including tremors, dystonia, sensory disturbances and dissociative episodes. Functional Movement Disorder (FMD), a common motor subtype of FND, specifically involves abnormal involuntary movements without an identifiable structural or organic cause. There isn't a validated assessment tool that currently exists to measure the specific impact of stress on motor symptom variability in FMD. The absence of such tools presents a barrier to accurate diagnosis, treatment planning, and longitudinal monitoring. This review focuses specifically on the FMD subtype, as it represents the most relevant phenotype for assessing stress-related motor dysfunction in the context of movement disorders. Following PRISMA-ScR guidelines, a systematic search was conducted across four major databases-PubMed, PsycINFO, Embase, and Scopus-using keywords related to FND, stress, motor symptoms, and psychometric evaluation. A total of 15 studies met inclusion criteria. Findings reveal a gap in available instruments: while several measures assess general stress (e.g., PSS-10, DASS-21) or motor symptoms (e.g., S-FMDRS), none are designed to capture the dynamic and stress-sensitive nature of motor dysfunction in FND. The review underscores the need for a patient-reported outcome (PRO) measure that is condition-specific, psychometrically validated, and capable of assessing real-time symptom variability linked to stress. Such a tool may offer significant benefits for clinical care and research by improving the precision of symptom monitoring, enhancing patient-provider communication, and guiding targeted interventions.