Is Functional Neurological Disorder the Same as Conversion Disorder?
Yes, functional neurological disorder (FND) and conversion disorder refer to the same clinical entity, with FND now being the preferred terminology in modern clinical practice. 1
Terminology Evolution
The condition has undergone significant nomenclature changes that reflect evolving conceptual understanding:
Historically, this disorder has been called conversion disorder, psychogenic disorder, psychosomatic disorder, somatoform disorder, and medically unexplained symptoms—terms that reflected different behavioral, physical, and psychological perspectives. 1
Currently, there is reasonable consensus among neurologists and psychiatrists that "functional" is the most appropriate diagnostic term, primarily to emphasize a disorder of function with aetiological neutrality. 1
In DSM-5 (2013), the official diagnostic term is "Functional Neurological Symptom Disorder," which serves as the umbrella term for these disorders that lie at the interface between neurology and psychiatry. 1
Why the Terminology Changed
The shift from "conversion disorder" to "functional neurological disorder" represents more than semantic preference:
The term "functional" emphasizes that this is a disorder of nervous system function rather than structure, avoiding implications about psychological causation. 2, 3
The older term "conversion" implied that psychological distress was being "converted" into physical symptoms—a "one size fits all" formulation that is no longer widely accepted. 4
The new terminology removes the DSM-IV requirement that psychological stress be a prerequisite for diagnosis, recognizing that symptoms often develop following injury, illness, or physiological events rather than psychological stressors. 2, 5
Clinical Implications of the Name Change
This terminology shift has important practical consequences:
Diagnosis is now made positively by identifying specific neurological signs (such as Hoover's sign, tremor entrainment, or give-way weakness) rather than simply excluding organic disease. 6, 5
The absence of psychological distress or trauma should not be taken as evidence against the diagnosis—symptoms frequently develop in the context of physical injury, infection, or medical illness rather than major adverse life events. 1, 2
Using "functional" rather than "conversion" or "psychogenic" helps avoid the perception that symptoms are "all in the patient's head" and emphasizes that symptoms are real, involuntary, and potentially reversible. 6, 2
Current Diagnostic Criteria
Under DSM-5, the diagnosis requires:
One or more symptoms of altered voluntary motor or sensory function that are incompatible with or not better explained by recognized neurological or medical conditions. 1
Symptoms cause clinically significant distress or impairment in functioning. 1
Each symptom type may be specified (e.g., "with swallowing symptoms" or "with speech symptoms"). 1
Bottom Line for Clinical Practice
When communicating with patients and colleagues, use "functional neurological disorder" or "FND" as the primary terminology, while recognizing that "conversion disorder" refers to the same condition. 7, 6 The term "functional" better facilitates therapeutic engagement by emphasizing treatability and avoiding stigmatizing implications about psychological causation. 6, 2