What are the changes in the diagnostic criteria for Conversion Disorder (Functional Neurological Symptom Disorder) across Diagnostic and Statistical Manual of Mental Disorders (DSM) versions III, III‑TR, IV, V, V‑TR and International Classification of Diseases (ICD) versions X and XI?

Evolution of Conversion Disorder/Functional Neurological Symptom Disorder Diagnostic Criteria

DSM Evolution (DSM-III through DSM-5-TR)

The most significant change across DSM versions was DSM-5's elimination of the requirement for psychological factors and the addition of positive neurological signs as diagnostic criteria, fundamentally shifting conversion disorder from a psychologically-based to a neurologically-based diagnosis. 1, 2

DSM-III and DSM-IV Era

• DSM-III and DSM-IV-TR required a temporal relationship between psychological factors and symptom onset or exacerbation as a core diagnostic criterion 1, 2
• Both versions required explicit exclusion of intentional symptom production (feigning) as a mandatory criterion 1, 2
• The diagnosis relied heavily on identifying psychological stressors temporally associated with neurological symptoms 2
• The term "conversion disorder" was retained, reflecting psychoanalytic theory of psychological conflict "converting" into physical symptoms 1

DSM-5 Revolutionary Changes

• DSM-5 abandoned the requirement for psychological factors entirely, recognizing that physical trauma or stress occurs in 37% of patients at symptom onset rather than psychological stressors 2
• The criterion excluding intentional production was relegated to accompanying text rather than mandatory criteria 1
• DSM-5 introduced the requirement for positive neurological signs showing internal inconsistency or incongruity with recognized neurological disease 1, 2
• The disorder was renamed "Functional Neurological Symptom Disorder" with conversion disorder as a parenthetical alternative, though the name change remains controversial 1, 3
• A cognitive symptoms subtype was added to capture the full spectrum of presentations 1
• The disease exclusion criterion was modified to require symptoms "not better explained" by neurological disease if present, rather than absolute exclusion 1

Evidence Supporting DSM-5 Changes

• Studies demonstrated that different forms of stress were found in equal proportions (20%) in patients with and without conversion disorder, indicating no specific psychological stressors 2
• Childhood abuse percentages varied widely from 0-85%, providing no reliable diagnostic marker 2
• "La belle indifference" occurred in only 3% of conversion disorder patients versus 2% of controls, eliminating its diagnostic utility 2
• Most positive clinical tests for partial paralysis, sensory disorders, and gait disorders demonstrated high specificity for the diagnosis 2

DSM-5-TR Modifications

• DSM-5-TR maintained the DSM-5 framework with minor clarifications but no fundamental criterion changes 4
• The emphasis on positive neurological signs and de-emphasis of psychological factors was preserved 4

ICD Evolution (ICD-10 through ICD-11)

ICD-11 represents the most substantial revision in psychiatric classification history, expanding from 11 to 21 disorder groupings and harmonizing with DSM-5's approach to functional neurological symptoms. 5

ICD-10 Framework

• ICD-10 maintained conversion disorder within the broader category of dissociative (conversion) disorders 4
• ICD-10 required positive signs of concurrent psychological distress in temporal association with neurological symptoms 4
• The absence of biological dysfunction underlying neurological symptoms was central to diagnosis 4

ICD-11 Major Restructuring

• ICD-11 eliminated the separate disorder grouping for mental and behavioral disorders with onset during childhood and adolescence, redistributing these across other groupings to emphasize developmental continuity across the lifespan 5
• The chapter expanded from 11 to 21 disorder groupings, representing the largest participative development process in mental health classification history 5, 6
• ICD-11 harmonized with DSM-5's structure and approach, including the emphasis on positive neurological signs over mandatory psychological factors 5

ICD-11 Dimensional Additions

• ICD-11 introduced dimensional symptom qualifiers that can be applied across disorders, including severity ratings (mild, moderate, severe) and remission status (partial or full) 6
• The system incorporated dimensional approaches while maintaining categorical diagnoses required for treatment justification and epidemiological data collection 5
• Field studies demonstrated 82.5-83.9% of clinicians rated ICD-11 as quite or extremely easy to use, with higher reliability and clinical utility compared to ICD-10 6, 7

ICD-11 Implementation

• ICD-11 was adopted by the 72nd World Health Assembly in May 2019 for implementation by WHO member states beginning January 1,2022 5, 6

Critical Diagnostic Considerations

Positive Neurological Signs

• Positive neurological signs showing internal inconsistency or incongruity with recognized disease patterns are now the cornerstone of diagnosis rather than psychological factor identification 1, 2
• These signs include Hoover's sign for leg weakness, tubular visual field defects, and non-anatomical sensory loss patterns 2

Psychological Factors Controversy

• The requirement for psychological factors was removed because studies showed no specific stressors distinguish conversion disorder patients from controls 2
• However, some experts argue that both positive neurological signs AND psychological signs should be considered to increase diagnostic certainty 4

Malingering Differentiation

• No reliable tests exist for distinguishing functional neurological symptom disorder from simulation or malingering 2
• The criterion for excluding intentional production was moved to accompanying text in DSM-5 because it cannot be reliably assessed 1

Neuroimaging Advances

• Recent neuroimaging studies have revealed complex neural underpinnings of functional neurological disorder, supporting its conceptualization as a genuine neurological condition rather than purely psychological 3
• Neuroimaging shows potential for predicting treatment response and understanding the disorder's multifaceted nature 3

Common Diagnostic Pitfalls

• Do not automatically diagnose functional neurological symptom disorder when initial medical workup is negative—repeated neurological assessments may reveal organic pathology, as demonstrated in cases where deep vein thrombosis was initially missed 4
• Do not rely on absence of psychological distress to exclude the diagnosis under DSM-5/ICD-11 criteria, as this is no longer required 4, 2
• Do not assume childhood trauma or "la belle indifference" support the diagnosis, as these lack diagnostic specificity 2
• Interdisciplinary assessment combining neurology and psychiatry perspectives remains essential for complex cases despite operationalized criteria 4