disability in medicine. Patients have often been misdiagnosed for years, correctly
diagnosed late, and subject to poorly delivered diagnoses that prevent diagnostic
understanding and lead to inappropriate treatments, iatrogenic harm, unnecessary and costly evaluations, and poor outcomes.
Observations: “Functional Neurological Symptom Disorder/Conversion Disorder” was adopted by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), replacing psychogenic with functional in the diagnostic labeling and removing the former criterion of psychological stress as prerequisite for FND. A diagnosis can now be made in an inclusionary manner by identifying neurological signs that are specific to FND, without reliance on presence or absence of
psychological stressors or “suggestive” historical clues. The new model of FND highlights a wider range of past sensitizing events such as physical trauma, medical illness, or (psycho)physiological events. In this model, strong ideas and expectations about these events correlate with abnormal predictions of sensory data and body- focused attention. Neurobiological abnormalities include hypoactivation of the
supplementary motor area and relative disconnection with areas that select/inhibit movements and are associated with a sense of agency. Promising evidence has accumulated for the benefit of specific physical rehabilitation and psychological interventions alone or in combination, but controlled trial evidence remains limited.
Conclusions and Relevance: FND are a neglected but potentially reversible source of disability. Further research is needed to determine the dose and duration of various interventions, the value of combination treatments and multidisciplinary therapy, and the patients best suited for each therapeutic modality.