Dissociative neurological symptom disorder

ICD-10F44.4–F44.7	Dissociative motor and sensory disorders
DSM-5-TRF44.4–F44.7	Functional Neurological Symptom Disorder (Conversion Disorder)

1. Definition and nosology

Dissociative Neurological Symptom Disorder (ICD-11: 6B60; DSM-5-TR: F44.4–F44.7 Functional Neurological Symptom Disorder / Conversion Disorder) — impairment of motor, sensory, or cognitive functions normally under voluntary control, not fully explained by a neurological or medical illness. Previously termed “conversion disorder” or “hysteria”.

2. History

• Charcot J.M. (19th century) — Studies on ‘hysteria’ at Salpêtrière.
• Freud S. — psychoanalytic “conversion” model.
• DSM-III (1980) — “Conversion Disorder” within somatoform disorders.
• DSM-5 (2013) — “Functional Neurological Symptom Disorder” — emphasis on joint neurological and psychiatric assessment.
• ICD-11 (2019) — transferred to the category of dissociative disorders.

3. Epidemiology

• In primary care and neurological clinics — 5–10% (reviews by Carson A.J. et al.).
• Sex: 2–3 times higher in females.
• Onset: adulthood, but also in children and the elderly.
• Comorbidity: MDD, anxiety, trauma history, somatic illnesses.

4. Etiology and pathogenesis

• A traumatic or stressful trigger is common, but in a substantial and variable proportion of patients no trigger can be identified (0–77% across studies; Ludwig L. et al. Lancet Psychiatry 2018 meta-analysis) — which is why DSM-5 and ICD-11 no longer require a stressor for diagnosis.
• Neurobiological — impaired sensorimotor and cognitive prediction processing; predictive coding hypothesis (Edwards M.J.).
• “Functional” term — not telling the patient it is “made up”, but a functional disorder of the nervous system.

5. Clinical features

Typical symptoms

• Motor: Weakness, paralysis, involuntary movements (functional tremor, dystonia), gait disturbance.
• Sensory: sensory loss (anesthesia), visual impairment (functional blindness), hearing impairment.
• Functional (psychogenic) non-epileptic seizures (PNES): during seizure-like episodes there is no epileptiform activity on EEG.
• Cognitive: “Foggy” concentration, slow processing — “functional cognitive disorder”.

Clinical signs (positive features).

• Signs that differ from typical neurological patterns (e.g., Hoover sign in motor weakness — positive indicator of functional component).
• Distractibility — symptom changes when attention is directed elsewhere.
• Entrainability — tremor adapts to another rhythm.

6. Diagnosis

6.1 Unified diagnostic criteria

A. Impairment of one or more motor, sensory, or cognitive functions.

B. Clinical findings demonstrate incompatibility of the disorder with known neurological or medical illness (positive clinical features).

C. Symptoms are not better explained by another psychiatric or medical condition.

D. Significant distress or functional impairment.

6.2 Differences between sources

• DSM-5-TR — diagnosis based on “positive features” (not an exclusion method); joint assessment by neurologist and psychiatrist.
• ICD-11 — in the category of dissociative disorders.

6.3 Diagnostic algorithm

1. Neurological examination — functional positive features (Hoover, entrainability, distractibility).
2. Exclusion of typical neurological conditions — MRI, EEG, EMG, lumbar puncture (according to clinical presentation).
3. In PNES cases — video-EEG monitoring is the gold standard.
4. Psychiatric evaluation — comorbid trauma, MDD, anxiety.
5. The patient’s diagnosis should be explained positively — “not fabricated, but a functional disorder of the nervous system”.

6.4 Differential diagnosis

7. Examination and assessment

• Neurological examination (positive features).
• Video-EEG — in PNES cases.
• MRI, laboratory exclusion of neurological disease.
• Trauma and psychiatric assessment.

8. Treatment

1. Positive explanation of the diagnosis to the patient — “Functional neurological disorder is not fabricated”; the structured explanation of diagnosis is critical for functional improvement (Stone J. summaries).
2. Multidisciplinary approach — neurologist + psychiatrist + physiotherapist.
3. Physiotherapy (for motor symptoms) — evidence-based benefit (Nielsen G. et al. J Neurol Neurosurg Psychiatry 2017 RCT).
4. CBT — cognitive restructuring; specific protocols for PNES (LaFrance W.C. JAMA Psychiatry 2014).
5. Against a background of trauma — trauma-focused approach.
6. Anticonvulsants for PNES are ineffective and harmful — accurate diagnosis of the patient and discontinuation of antiepileptic drugs is critical.
7. SSRIs for comorbid depression/anxiety.

8.1 Treatment methods

1. Positive clinical diagnosis presentation — Stone (Stone J.) — The diagnosis is made by ruling in, not by ruling out; positive clinical signs explained to patient (e.g., Hoover sign demonstrated).
2. Physiotherapy for FND — Specific manual training, movement instruction; Nielsen G. et al. J Neurol Neurosurg Psychiatry 2017.
3. CBT for PNES — LaFrance (LaFrance W.C.) — Manualized 12 sessions; seizure diary, cognitive restructuring; LaFrance W.C. et al. JAMA Psychiatry 2014.
4. Video-EEG — PNES diagnosis gold standard.

8.2 Differences between sources

• FND-specific international consensus (Stone J., Carson A., LaFrance W.C.).
• NICE — multidisciplinary approach for functional symptoms.

9. Prognosis

• Improvement with early accurate diagnosis and intervention.
• Late diagnosis and polypharmacy — chronicity.

10. Myths and misconceptions

Myth 1: “The patient is malingering / ‘faking’”

Evidence: Functional disorder is a real clinical condition — functional impairment of the nervous system; positive clinical signs prove it. It is distinct from factitious disorder and simulation.

Myth 2: “Anticonvulsants are needed for PNES”

Evidence: Anticonvulsants ineffective in PNES, cause polypharmacy side effects; correct diagnosis and discontinuation of antiepileptic drugs is critical.

Myth 3: “Functional impairment is psychological ‘weakness’, not physical”

Evidence: Functional disorder is a biological process of the nervous system; requires joint psychiatric and neurological assessment.

Myth 4: “Just ‘dumping’ the patient on a psychiatrist is enough”

Evidence: Neurologist and psychiatrist must collaborate; ‘dismissing’ the patient disrupts therapeutic alliance and reduces the chance of improvement.

Myth 5: “Functional symptoms are not treatable”

Evidence: Physiotherapy, CBT, multidisciplinary approach show a significant effect.

11. Sources

1. WHO. ICD-11. 6B60 Dissociative neurological symptom disorder. 2024.
2. APA. DSM-5-TR. 2022.
3. Stone J., Carson A. Functional neurological disorders: the neurological assessment as treatment. Pract Neurol 2016;16(1):7–17.
4. Nielsen G. et al. Physiotherapy for functional motor disorders: a consensus recommendation. J Neurol Neurosurg Psychiatry 2015;86(10):1113–1119.
5. LaFrance W.C. et al. Multicenter pilot treatment trial for psychogenic nonepileptic seizures: a randomized clinical trial. JAMA Psychiatry 2014;71(9):997–1005.
6. Edwards M.J., Adams R.A., Brown H., Pareés I., Friston K.J. A Bayesian account of “hysteria”. Brain 2012;135(Pt 11):3495–3512.