Functional neurological disorder
Exam Tips
- In UK exams, state that FND is a positive clinical diagnosis, not merely diagnosis of exclusion.
- Name at least two positive signs (for example Hoover's sign and distractibility/entrainment of tremor) and explain what they demonstrate.
- For seizure-like episodes, always mention immediate exclusion of ongoing epileptic status and other acute medical causes before confirming dissociative seizures.
- Communication station pearl: validate that symptoms are real, explain brain network dysfunction in plain language, and avoid pejorative terms such as 'pseudoseizure' or 'non-organic'.
- Management marks come from MDT planning (neurology + neuropsychiatry/psychology + specialist physio), treatment of comorbidity, and reducing iatrogenic harm.
- Image reference: see illustrative diagrams of Hoover's sign, hip abductor sign, and functional gait patterns in the FND Action clinician guidance figures and standard neurology OSCE atlases.
Definition
Functional neurological disorder (FND) is a common neurological condition in which genuine symptoms arise from abnormal nervous system functioning (a problem of brain network operation) rather than structural damage such as stroke, tumour, or demyelination. It is diagnosed positively using characteristic clinical features (internal inconsistency and incongruence with recognised neuroanatomy), and causes substantial morbidity across motor, sensory, seizure-like, speech, cognitive, and balance domains.
Pathophysiology
Current models describe FND as a brain network disorder involving disrupted interaction between sensorimotor, salience/attention, limbic (threat-emotion), and self-agency networks. A biopsychosocial framework is most useful: predisposing factors (for example prior illness, trauma history, neurodivergence, pain syndromes), precipitating events (injury, acute stress, panic, migraine, infection), and perpetuating factors (fear-avoidance, symptom hypervigilance, deconditioning, stigma, maladaptive illness beliefs). Mechanistically, altered top-down predictions and attention can override normal motor/sensory processing, so involuntary symptoms are experienced as real and outside voluntary control.
Risk Factors
- Female sex (overall higher prevalence; sex gap narrows with increasing age)
- Coexisting anxiety, depression, chronic pain, fatigue, irritable bowel syndrome, or migraine
- Pre-existing neurological disease (FND can coexist with organic neurological diagnoses)
- Neurodivergence (for example autism spectrum condition or ADHD)
- Childhood or adult trauma/stressful life events (not required for diagnosis)
- Physical trauma including accident or head injury
- Social stressors, reduced support, and stigma-related barriers to care
Clinical Features
Symptoms
- Motor gain phenomena: tremor, dystonia, jerks, tics, fixed postures
- Motor loss phenomena: limb or facial weakness, episodes of paralysis
- Functional seizures/dissociative seizures (often prolonged, fluctuating, or with pauses)
- Sensory symptoms: numbness, paraesthesia, visual or hearing disturbance, tinnitus
- Speech and voice disturbance
- Gait disturbance and imbalance
- Persistent postural-perceptual dizziness pattern (non-vertiginous dizziness worsened upright/in visually busy environments)
- Cognitive complaints: poor concentration, memory lapses, word-finding difficulty
Signs
- Internal inconsistency over time or with distraction/redirection
- Incongruence with recognised neuroanatomical patterns
- Hoover's sign: weak hip extension normalises with contralateral hip flexion against resistance
- Hip abductor sign: apparent weakness improves with contralateral effort
- Give-way/collapsing weakness not explained by pain
- Functional gait signs: monoplegic dragging, sudden knee buckling, marked slowness/hesitation despite preserved balance strategies
- Marked sway on Romberg without true falls, often attention-dependent
- Variable tremor amplitude/frequency and entrainment with rhythmic tasks
- Disproportionate effort behaviours (huffing, grimacing, breath-holding) during examination
Investigations
Management
Lifestyle Modifications
- Give a clear, validating explanation that symptoms are real, common, and potentially reversible; explicitly share positive examination signs used for diagnosis
- Co-produce a rehabilitation plan with early graded return to normal movement, function, education/work, and activity pacing
- Specialist physiotherapy/occupational therapy using motor retraining, attention redirection, and reduction of maladaptive movement patterns
- Psychological therapy (often CBT-informed; trauma-focused work when indicated) targeting symptom beliefs, threat processing, and avoidance
- Address sleep, pain, migraine triggers, alcohol/substance use, and social stressors; involve family/carers to reduce reinforcement of disability
- Safety-net for new neurological red flags and avoid repeated low-value investigations once diagnosis is established
Pharmacological Treatment
Core FND symptoms
- No medication has proven disease-modifying efficacy for core FND symptoms
Avoid polypharmacy and iatrogenic harm; review and deprescribe ineffective drugs. Do not start antiseizure medication for dissociative seizures unless there is confirmed comorbid epilepsy.
Comorbid depression/anxiety (BNF-aligned examples)
- Sertraline 50 mg once daily initially; increase in 50 mg steps to usual maximum 200 mg daily
- Fluoxetine 20 mg once daily initially; may increase to 40-60 mg daily if needed
Use standard SSRI cautions: early agitation/suicidal ideation risk (especially under 30), serotonin syndrome interactions, hyponatraemia, GI bleeding risk (higher with NSAIDs/anticoagulants), and withdrawal symptoms if stopped abruptly.
Comorbid neuropathic-type pain/headache overlap (selected cases)
- Amitriptyline 10 mg at night initially; titrate gradually (commonly 25-75 mg nightly for pain)
- Propranolol for migraine prevention: 40 mg two to three times daily initially, titrated to response
Amitriptyline: anticholinergic effects, sedation, QT-risk, overdose toxicity; avoid/caution in significant cardiac disease, glaucoma, urinary retention. Propranolol: contraindicated in asthma, severe bradycardia, or heart block; caution in diabetes (masks hypoglycaemia).
Complications
- Persistent disability with impaired mobility, self-care, employment, and social participation
- Reduced quality of life comparable to other chronic neurological disorders
- Comorbid anxiety, depression, chronic pain, fatigue, and dissociative symptoms
- Stigma, diagnostic invalidation, and mistrust of healthcare
- High healthcare utilisation (including repeated ED/neurology attendances)
- Increased mortality compared with the general population (multifactorial; mechanism uncertain)
Prognosis
Course is often relapsing-remitting with fluctuating symptom burden; many patients have persistent symptoms over years, while a minority achieve full remission. Better outcomes are linked to early confident diagnosis, good explanation, and timely multidisciplinary treatment. Poorer outcomes are associated with long symptom duration, severe disability, chronic pain/depression/personality difficulties, fixed abnormal movement patterns, social isolation, and entrenched illness beliefs or adversarial medicolegal context.
Sources & References
🏥BMJ Best Practice(2)
✅NICE Guidelines(1)
- Functional neurological disorder[overview]
📖Textbook References(7)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1071)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1016, 1017)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1831)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 287)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 209)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1028, 1029)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 287)[context]