Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Diagnose functional or dissociative seizures from positive clinical evidence, protect patients from iatrogenic emergency treatment and stigma, identify coexisting epilepsy, and communicate a credible rehabilitation-focused treatment plan.
Functional seizures are episodes of impaired awareness, responsiveness or movement generated by a disorder of nervous-system functioning rather than epileptic cortical discharges. They may involve shaking, collapse, motionless unresponsiveness or staring. Predisposing, precipitating and perpetuating factors differ substantially between people; trauma, anxiety or depression may be relevant for some but are neither universal nor required for diagnosis. Calling the events stress alone or saying tests are normal fails to provide a positive neurological formulation.
Semiology is interpreted probabilistically. Long duration, waxing and waning intensity, asynchronous or side-to-side movement, eye closure with resistance, retained recall or modulation by interaction can point towards a functional event. Yet syncope, frontal lobe seizures, movement disorders and sleep events can overlap. A clear smartphone video reviewed by an expert is often valuable. The strongest confirmatory test is simultaneous video-EEG capture of the person’s usual event with clinical features of a functional seizure and no corresponding epileptic activity, while acknowledging that some focal seizures are difficult to see on scalp EEG.
Functional seizures arise from interacting attentional, arousal, learning and neurobiological factors rather than deliberate production or conscious simulation.
Illness, injury, panic, pain or adverse experience may precede onset, although no single stressor is required for diagnosis.
Some people have both functional and epileptic seizures, which can shape expectations, emergency responses and symptom learning.
Fear, hypervigilance, avoidance, sleep disruption and repeated emergency treatment can reinforce attack networks after the original trigger has passed.
Some models propose that internal sensations or contextual cues acquire excessive salience and trigger an involuntary defensive or dissociative state.
Functional disruption of awareness, movement and autonomic control occurs without the hypersynchronous cortical discharge that defines an epileptic seizure.
The resulting episode can produce unresponsiveness, shaking, collapse or sensory change with variable duration and preserved physiological stability.
Alarm, avoidance and iatrogenic intervention can reinforce expectations of danger, increasing recurrence unless a credible rehabilitation model replaces them.
A prolonged episode with pauses, changing intensity, asynchronous thrashing or side-to-side head movement can support functional seizure when the whole video and context are assessed by an experienced clinician.
Motionless apparent unresponsiveness lasting many minutes, sometimes with partial recall or an escalating bodily warning, may represent a functional seizure rather than sleep, syncope or focal epilepsy.
Sustained eye closure during a convulsive-appearing event, particularly with resistance to opening, can add diagnostic weight but should never function as a solitary bedside test.
A separate stereotyped brief event with lateralised onset, injury, postictal confusion or epileptiform evidence should be characterised independently rather than folded into the functional diagnosis.
Repeated benzodiazepines, intubation or critical-care admission for prolonged stable events despite prior functional diagnosis signals the need for an accessible, specific emergency plan and staff education.
Stereotyped onset, lateral tongue injury, postictal change and ictal EEG support epilepsy, although scalp recordings can miss selected focal seizures.
Presyncope, pallor, a trigger and rapid recovery favour hypoperfusion; brief jerks are common during syncope and cerebral hypoperfusion.
Prominent fear, hyperventilation and retained interaction may suggest panic, but functional seizures can include similar autonomic symptoms.
Tics, dystonia, parasomnia and REM behaviour have characteristic timing, urge, posture or sleep-stage relationships during assessment.
Repeated benzodiazepines, restraint and intubation can cause hypoventilation, aspiration and procedure injury during physiologically stable functional events.
Misdiagnosis produces sedation, reproductive risk, interactions and monitoring without treating the functional mechanism during prolonged treatment.
Unpredictable loss of control creates collision risk and work or financial consequences even after epilepsy has been confidently excluded.
Disbelief and fragmented explanations worsen shame, avoidance, healthcare use and disengagement from effective rehabilitation over time.
Showing the observed features that support FND is more credible and safer than saying MRI and routine EEG were normal, because normal tests occur in epilepsy too.
Functional symptoms are not consciously produced; malingering and factitious disorder are different constructs and should not be insinuated through ambiguous language.
A concise description of the habitual event, expected duration and escalation triggers can reduce repeated benzodiazepines and intubation while preserving reassessment for genuine emergencies.
When epilepsy and functional seizures both occur, family and emergency teams need distinguishing features and separate rescue thresholds rather than one generic seizure instruction.
FND-informed psychological treatment can address warning signals, attention, dissociation, avoidance and comorbidity even when no trauma or current stressor is identified.
Diagnosing functional seizures solely because routine EEG and MRI are normal mistakes absence of evidence for positive diagnostic evidence.
Administering escalating benzodiazepines to every prolonged stable habitual event can cause respiratory depression, intubation and intensive-care harm.
Telling a patient that episodes are just stress or all in the mind invalidates involuntary symptoms and offers no treatment mechanism.
Withdrawing all antiseizure medicine immediately after one functional event can expose unrecognised coexisting epilepsy and precipitate withdrawal seizures.
Ending neurological follow-up at diagnosis leaves communication, rehabilitation, driving, comorbidity and possible diagnostic evolution without clinical ownership.
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A patient has prolonged fluctuating shaking episodes despite two antiseizure medicines. Routine interictal EEG is normal, and a witness video suggests functional features. Which investigation most directly strengthens diagnostic certainty?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
Never stop abruptly or taper before all event phenotypes and the original epilepsy evidence are reviewed. Some people have both conditions, and benzodiazepine or barbiturate withdrawal requires a particularly slow specialist schedule.
Agree a named target and monitor response. Avoid sedative polypharmacy, opioid escalation and adverse interactions, and do not imply that prescribing proves a purely psychiatric cause.