Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Functional neurological disorder
Psychiatry · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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New neurological emergency
First, prolonged or injurious seizure-like events, new focal deficit, reduced consciousness, severe headache, pregnancy, metabolic disturbance or physiological instability must be assessed urgently before an established functional diagnosis is invoked.
Action: Use ABCDE, check glucose and relevant reversible causes, follow stroke or seizure pathways when indicated, prevent injury without harmful restraint, and seek urgent neurological or acute medical review for new signs or a changed pattern.
Overview
Make and communicate a rule-in diagnosis of functional neurological disorder, distinguish new emergencies and comorbidity, and support multidisciplinary rehabilitation without implying feigning or diagnostic closure.
Functional neurological disorder presents with genuinely experienced motor, sensory or seizure-like symptoms caused by altered functioning of nervous-system networks rather than a structural lesion that explains the pattern. Diagnosis is positive. A clinician identifies signs that are characteristic of functional symptoms within an appropriate neurological assessment; normal tests alone are insufficient and psychological adversity is neither necessary nor diagnostic.
Positive motor signs demonstrate preserved capacity under different conditions. In functional leg weakness, hip extension may improve when the opposite hip flexes against resistance; in functional tremor, rhythm may change with distraction or entrainment. Such signs must be elicited and interpreted competently. They are useful because they show how attention and automatic movement influence function, not because they catch the patient out.
Practice
Two practice questions
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PsychiatryOriginal SBA
Rule-in functional weakness
A woman with variable right leg weakness has greater hip extension when the left hip flexes against resistance than during direct testing. MRI does not explain the deficit. Which finding most supports FND?
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Functional seizures are episodic events resembling epilepsy without the epileptic electrical mechanism. Event history, witness description, video and specialist assessment are central; video-EEG may be needed when diagnostic uncertainty persists. Antiseizure drugs do not treat functional seizures unless epilepsy also exists, but medication should not be stopped abruptly before diagnostic and prescribing review.
Communication influences outcome. State that FND is common, recognised and treatable; explain which positive feature supports the diagnosis; acknowledge uncertainty and comorbidity; and check what the person heard. A purely psychogenic explanation, a statement that nothing is wrong or an unsolicited assumption about trauma can produce shame and disengagement.
Rehabilitation retrains function using attention-shifting, automatic movement, graded practice and reduction of unhelpful compensatory strategies. Occupational therapy addresses routines, fatigue, equipment and participation; psychological therapy may target threat, avoidance, trauma, anxiety or adjustment when relevant. Goals are meaningful activities and self-management, with a relapse plan and route for reassessment of genuinely new neurological signs.
Key points
FND is a disorder of neurological functioning and is diagnosed through positive clinical features, not simply because imaging or laboratory tests are normal.
Internal inconsistency means a function changes with task, attention or automatic movement; it does not mean the person is deliberately inconsistent.
Examples include Hoover or hip-abductor signs, distractible or entrainable tremor, and specialist recognition of functional-seizure semiology.
Explain the diagnosis clearly, name it, show a positive sign with permission and emphasise that symptoms are real and potentially reversible.
FND can coexist with epilepsy, multiple sclerosis, migraine, Parkinsonism or other neurological disease; new symptoms are assessed normally.
Treatment is individualised rehabilitation, commonly involving neurology, specialist physiotherapy, occupational therapy and psychological expertise.
Trauma, stress, anxiety or depression may be relevant but are not required to diagnose FND and should not be presumed.
Functional seizures require driving advice: the person must stop driving and notify DVLA, with relicensing determined by current standards and specialist review.
Aetiology
01
Multifactorial vulnerability
Biological predisposition, illness, injury, attention, expectation, learning, stress and social context may combine differently; no single psychological cause is required.
02
Precipitating events
Symptoms may begin after pain, migraine, infection, panic, surgery or injury, yet the initiating event may not explain why altered function persists.
Pathophysiology
1
Altered motor prediction
Mismatch between intended movement, attention and predicted sensory consequences can impair voluntary control despite preserved basic motor pathways.
2
Attention-dependent function
Over-focused conscious control may disrupt movement that improves during distraction, rhythm or automatic goal-directed activity, producing positive inconsistency.
3
Threat and learning networks
Arousal, symptom expectations and reinforced avoidance can stabilise abnormal movement or event patterns without deliberate production.
Clinical features and red flags
Functional limb weakness
Weakness shows positive internal inconsistency, such as improved hip extension during contralateral effort, while examination still considers pain, neglect and organic disease.
Functional movement disorder
Tremor may be distractible, variable or entrain to another rhythm; gait patterns may improve with altered attention or automatic movement.
Functional seizures
Events require specialist semiological assessment because duration, movement, responsiveness and recovery patterns overlap imperfectly with epilepsy and syncope.
Functional sensory symptoms
Altered sensation or vision may follow patterns incompatible with a single anatomical lesion, but positive interpretation requires neurological expertise and context.
Symptom variability
Symptoms may fluctuate with attention, fatigue, stress or context; variability is a clinical feature rather than evidence of fabrication.
Red flags requiring action
Sudden persistent focal deficit, aphasia, visual loss or severe imbalance requires time-critical stroke assessment regardless of previous FND.
A first seizure-like episode, status, cyanosis, significant injury, pregnancy or failure to regain baseline needs acute medical evaluation.
Progressive objective neurological signs, cognitive decline, systemic illness or a substantially different event pattern should reopen the differential.
Investigations
01Positive neurological examinationFirst step
Why
Identify reproducible signs characteristic of functional weakness, movement or sensory disturbance within a complete relevant examination.
Interpretation and limitations
A valid positive sign supports a rule-in diagnosis; poor effort, normal imaging or inconsistency described without a recognised sign does not.
02Event history and video
Why
Characterise warning, awareness, movement, duration, injury, recovery and context of seizure-like episodes using witness accounts or safe recordings.
Interpretation and limitations
Patterns can raise or lower suspicion but should be integrated by an experienced clinician; one feature rarely distinguishes functional seizure from epilepsy.
03Video electroencephalography
Why
Capture a typical event with simultaneous behaviour and EEG when epilepsy and functional seizures remain difficult to separate.
Interpretation and limitations
A typical clinical event without epileptic correlate supports functional seizures, but some epileptic seizures have limited surface EEG change and require specialist interpretation.
04Targeted structural testing
Why
Investigate plausible neurological or systemic alternatives and coexisting disease according to history, examination and change over time.
Interpretation and limitations
Normal results do not
Differential diagnosis
01
Epilepsy or syncope
Seizure-like events require history, witness evidence and sometimes video-EEG because epilepsy, cardiac syncope and functional seizures can overlap or coexist.
02
Structural neurological disease
Stroke, demyelination, neuropathy, myopathy and movement disorders produce characteristic patterns that may be absent, incidental or present alongside functional signs.
03
Factitious or feigned symptoms
Intentional symptom production is a separate determination requiring evidence of conscious behaviour; fluctuation or a positive functional sign does not establish it.
1Name FND and validate that the symptom is real, involuntary and produced by altered nervous-system functioning.
2With permission, demonstrate the positive sign and explain that preserved capacity under different conditions creates a rationale for retraining.
3Check understanding, address concerns about missed disease and provide a written plan for rehabilitation, comorbidity and new symptoms.
02RehabilitationRetrain function collaborativelyThe diagnosis is understood sufficiently to set activity-based recovery goals.+
1Identify a baseline and practise automatic, goal-directed movement using distraction or altered attention rather than repeated maximal strength testing.
2
Complications
01
Mobility and participation loss
Falls, fear, deconditioning and unnecessary restriction can reduce independence, education, employment and social roles despite preserved neurological capacity.
02
Emergency treatment harm
Misinterpreted functional seizures may lead to repeated benzodiazepines, unnecessary intubation, antiseizure polypharmacy, prolonged admission and intensive-care complications.
03
Stigma and disengagement
Explanations that imply feigning or hidden trauma can damage trust, obstruct rehabilitation and drive repeated consultations for a credible diagnosis.
Monitoring and follow-up
Track task-specific function, falls, injuries, participation and self-efficacy rather than asking only whether symptoms have disappeared.
Document whether events remain typical, their frequency and recovery, and any features suggesting epilepsy, syncope or another new disorder.
Review pain, fatigue, sleep, mood, trauma symptoms, substance use and adverse effects of medicines that may obstruct rehabilitation.
Revisit the person's understanding of the diagnosis and correct language that implies damage, feigning or inevitable chronicity.
Confirm driving and occupational safety advice, coordination between services, and a clear route for review of new neurological signs.
Special situations
Positive signs are therapeutic
When demonstrated respectfully, a positive sign supplies diagnostic evidence and shows preserved capacity that rehabilitation can use, making the explanation more than reassurance after normal tests.
Dual diagnosis is common
Functional seizures can coexist with epilepsy and functional motor symptoms with structural neurological disease, so treatment must specify which evidence supports each component.
Equipment can help or hinder
Aids may preserve safety and participation, but unnecessarily fixed dependence can reduce automatic movement practice; occupational and physiotherapy review should balance both effects.
Trauma inquiry needs consent
Ask sensitively when clinically relevant and explain why, but do not require disclosure, infer hidden trauma or make recovery conditional on a psychological narrative.
Driving is a clinical intervention
For dissociative or functional seizures, clear stop-driving and DVLA notification advice protects the patient and public while specialist evidence informs any later licensing decision.
Common pitfalls
01
Diagnosing FND only because scans are normal or symptoms seem unusual, without a recognised positive clinical feature.
02
Describing inconsistency as poor effort, which confuses an involuntary functional mechanism with deception.
03
Telling the person that nothing neurological is wrong or that symptoms are all due to stress.
04
Stopping antiseizure medication abruptly after suspected functional seizures before epilepsy and withdrawal risk have been reviewed.
05
Sending every typical established event through repeated invasive emergency pathways while failing to create an individual safety plan.
06
Attributing new focal signs to FND and thereby delaying assessment of stroke, epilepsy, inflammatory disease or another comorbidity.
Suicidal intent, repeated injury, unsafe driving, severe self-neglect or safeguarding vulnerability requires urgent coordinated action.
themselves diagnose FND; a structural abnormality may be causal, incidental or comorbid and must be clinically correlated.
Preserved automatic movement and task-specific variability guide retraining, while risk, pain and comorbidity shape pace and setting.
Address sleep, pain, fatigue, anxiety, trauma or mood as relevant while occupational therapy supports routines, participation and proportionate equipment.
3Measure meaningful function, build a self-management and relapse plan, and coordinate messages across neurology, primary care and therapy.
03Recurrent eventUse a safe functional-seizure planA previously characterised functional seizure occurs in its usual pattern without acute red flags.+
1Protect from injury, avoid restraint or objects in the mouth, maintain calm observation and follow the person's agreed emergency plan.
2EscalationAvoid repeated emergency medication or invasive escalation solely because an established typical event is prolonged, unless clinical features create acute concern.
3After recovery, identify triggers or injury, reinforce driving restrictions and seek reassessment if the pattern, neurology or recovery has changed.