Positive Clinical Signs in Functional Neurological Disorders: A Narrative Review and Development of a Clinical Decision Tool. [Review]

Abstract

Background: Functional Neurological Disorders (FNDs) encompass a spectrum of disabling conditions, including functional limb weakness, tremor, gait disorders, seizures, and cognitive impairments. While previously diagnosed by exclusion, a growing consensus now supports the use of positive clinical signs as a basis for diagnosis. Despite this paradigm shift, frontline clinicians lack an integrated, accessible clinical tool for guiding diagnostic reasoning across FND subtypes. Objectives: This study aims to (1) synthesize the contemporary evidence on positive clinical signs across major FND subtypes and (2) develop a structured Clinical Decision Tool to support early and confident diagnosis in routine clinical settings. Methods: A focused narrative review was conducted using peer-reviewed publications and neurology reference texts, identifying reproducible positive clinical signs relevant to FND diagnosis. Signs were extracted, tabulated by subtype, and integrated into a modular decision-making framework designed for usability across outpatient, emergency, and specialist contexts. Results: The review identified 60+ positive signs across seven FND subtypes. These include Hoover's sign for limb weakness, entrainment for tremor, variable responsiveness in NESs, and paradoxical memory performance in Functional Cognitive Disorder. A Clinical Decision Tool was developed, featuring subtype-specific checklists, diagnostic confidence indicators, and red flag alerts, and it is currently available in printable format. Conclusions: This study offers a novel, evidence-based decision tool to facilitate the positive diagnosis of FND. By consolidating observable signs into a practical format, it aims to reduce diagnostic delays, avoid unnecessary investigations, and enhance patient-clinician communication. Future efforts will focus on clinical validation and digital implementation.