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← Paediatrics and child health indexChapter sections
OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

First afebrile seizure assessment

Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Ongoing seizure or incomplete recovery

A convulsive seizure lasting five minutes, repeated seizures without recovery, persistent focal deficit, cardiorespiratory compromise, severe hypoglycaemia, poisoning, meningism or major head injury requires emergency treatment and hospital assessment.

Action: Use ABCDE, protect the airway without restraining the child, give oxygen when hypoxaemic, check capillary glucose promptly and follow the paediatric convulsive-status algorithm while seeking senior paediatric help.

Overview

Recognise a likely first unprovoked seizure, separate it from common childhood mimics, identify acute symptomatic causes and organise urgent specialist assessment without prematurely diagnosing epilepsy.

Start with the circumstances: sleep or wakefulness, posture, exercise, pain, fever, illness, fasting, flashing light, medication or possible toxin. Ask for an uninterrupted witness account before suggesting features. Establish eye and head direction, initial limb, symmetry, colour, breathing, responsiveness, automatisms, duration, injury, tongue bite, incontinence and recovery. Phone video can be diagnostically valuable when consent and privacy are respected.

Clarify whether the event was provoked. Measure temperature and glucose where clinically indicated and review diabetes, vomiting, endocrine or renal disease, recent head injury, infection, prescribed and non-prescribed substances. A first seizure during an acute insult follows a different recurrence pathway from an unprovoked seizure, although both may require emergency care.

Examine vital signs, hydration, skin for neurocutaneous marks or injury, cardiovascular system, development and a complete neurological examination including fundoscopy when competent. Todd paresis should improve, but persistent weakness or altered consciousness requires urgent imaging and infection or vascular assessment rather than routine outpatient referral.

Aetiology

01

Unprovoked epileptic seizure

Transient cortical network dysfunction can occur without an immediate reversible insult and may be the first manifestation of an epilepsy syndrome.

02

Acute symptomatic seizure

Hypoglycaemia, electrolyte disturbance, infection, toxin, trauma, hypoxia or acute vascular injury can provoke a seizure requiring treatment of the cause.

03

Structural predisposition

Congenital malformation, remote perinatal injury, tumour, previous infection or traumatic scar can create a persistent epileptogenic network.

04

Genetic developmental epilepsy

Pathogenic ion-channel or developmental variants may produce age-linked seizure types, electroencephalographic patterns and associated learning or movement differences.

Pathophysiology

  1. 1
    Synchronous cortical discharge

    Excess excitation or reduced inhibition recruits neuronal networks abruptly, generating motor, sensory, autonomic, cognitive or awareness disturbance.

  2. 2
    Focal network onset

    Discharge beginning in one hemisphere produces lateralised symptoms and may spread bilaterally into a tonic-clonic convulsion.

  3. 3
    Generalised network onset

    Rapid bilateral thalamocortical recruitment can impair awareness or cause myoclonic, tonic, atonic or tonic-clonic activity from the outset.

  4. 4
    Postictal suppression

    Temporary network inhibition and metabolic exhaustion after the discharge cause sleepiness, confusion, headache or a transient focal Todd paresis.

Clinical features and red flags

Focal onset

Forced head or eye deviation, unilateral clonic activity, asymmetric tonic posture, aura or postictal unilateral weakness indicates a focal network.

Generalised convulsion

Abrupt loss of awareness, bilateral tonic stiffening then rhythmic clonic jerks, followed by stertorous breathing and postictal sleep supports tonic-clonic seizure.

Convulsive syncope

Pallor, autonomic prodrome and rapid orientation favour syncope even when several brief myoclonic jerks accompany cerebral hypoperfusion.

Postictal state

Gradually improving confusion, fatigue, headache or temporary Todd paresis supports seizure but prolonged deterioration is a red flag.

Acute symptomatic context

Fever, metabolic illness, toxin access, trauma or new neurological deficit directs immediate cause-specific assessment before syndrome classification.

Red flags requiring action

  • A seizure continuing for five minutes or more should be treated as convulsive status epilepticus rather than observed for spontaneous resolution.
  • Failure to recover progressively, persistent unilateral weakness, new speech loss or unequal pupils raises intracranial infection, haemorrhage, stroke or mass effect.
  • Fever with neck stiffness, non-blanching rash, bulging fontanelle, marked irritability or encephalopathy requires an urgent meningitis or encephalitis pathway.

Investigations

  1. 01
    First-line witness history and videoFirst stepFirst line
    Why
    Establish whether the event was epileptic and classify its likely onset before ordering tests.
    Interpretation and limitations
    Consistent focal or generalised semiology is more informative than a single nonspecific laboratory or EEG abnormality.
  2. 02
    Twelve-lead ECG
    Why
    Identify long-QT syndrome, pre-excitation, conduction disease or another cardiac cause of collapse.
    Interpretation and limitations
    An abnormal trace or exertional phenotype needs urgent cardiac review; a normal ECG does not exclude every intermittent arrhythmia.
  3. 03
    Targeted capillary and venous tests
    Why
    Detect hypoglycaemia, electrolyte disturbance, infection, toxin or organ dysfunction when the clinical context supports them.
    Interpretation and limitations
    Correct a dangerous abnormality immediately and classify the event as acute symptomatic if causally linked.
  4. 04
    Electroencephalography
    Why
    Support epilepsy diagnosis and identify focal, generalised or syndrome-specific epileptiform activity.
    Interpretation and limitations
    Request promptly when indicated, ideally within 72 hours after a first seizure; normal results cannot exclude epilepsy.
  5. 05

Differential diagnosis

01

Vasovagal syncope

Prodromal warmth, pallor, nausea, visual dimming and rapid recovery when supine favour cerebral hypoperfusion, although brief stiffening or jerks can occur.

02

Cardiac syncope

Sudden exertional collapse, palpitations, injury without warning, abnormal ECG or family sudden death demands urgent cardiac assessment.

03

Reflex anoxic or breath-holding event

Pain, fright or crying can trigger pallor or cyanosis, brief loss of tone and stiffening in younger children without epilepsy.

04

Functional non-epileptic event

Variable prolonged movements, eye closure and fluctuating responsiveness may suggest a functional event, but diagnosis requires positive specialist evidence and respectful explanation.

05

Sleep or movement phenomenon

Parasomnias, tics, stereotypies, shuddering and dystonia have characteristic triggers and preserved awareness that careful video review can reveal.

Management

01EmergencyStabilise and stop prolonged seizureFirst stepThe event continues for five minutes or recovery is unsafe.+
  1. 1Use ABCDE, time the seizure, protect the child and check glucose without delaying treatment.
  2. 2Follow the paediatric status algorithm and treat infection, toxin, trauma or metabolic disturbance in parallel.
  3. 3EscalationEscalate persistent altered consciousness, focal deficit or cardiorespiratory compromise for urgent imaging and critical care.
02ReconstructDecide whether seizure is likelyThe child has recovered after a first afebrile paroxysmal event.+
  1. 1Obtain child, witness and video descriptions of prodrome, onset, movements, awareness and recovery.
  2. 2Examine cardiovascular and neurological systems and review development, medicines, family history and provoking factors.

Complications

01

Recurrent prolonged seizure

A future seizure may persist into status epilepticus, so families need first-aid teaching and an individual rescue plan when risk warrants.

02

Injury and aspiration

Loss of awareness can cause falls, burns, drowning or aspiration, particularly around baths, heights, traffic and unsupervised swimming.

03

Missed acute cause

Attributing every convulsion to epilepsy can delay treatment of hypoglycaemia, infection, poisoning, arrhythmia or raised intracranial pressure.

04

Psychosocial restriction

Premature labelling can create school exclusion, anxiety and unnecessary activity restriction before the diagnosis and recurrence risk are established.

Monitoring and follow-up

  • Confirm the urgent specialist appointment, ECG review and ownership of any EEG or imaging request.
  • Ask families to record event timing, possible triggers, recovery and safe video if another episode occurs.
  • Review school attendance, anxiety, sleep and activity restriction so provisional diagnosis does not create avoidable disability.
  • Reassess immediately for another seizure lasting five minutes, clustering, injury, fever with meningism or incomplete recovery.
  • If treatment begins, monitor seizure type and frequency, adherence, cognition, mood, growth and medicine-specific laboratory or reproductive risks.
  • Update the written safety plan when diagnosis, recurrence risk, rescue threshold or school circumstances change.

Special situations

Jerks do not prove epilepsy

Brief myoclonic movements are common during syncope, so sequence, colour, prodrome and recovery carry more diagnostic weight.

EEG supports rather than vetoes

Interictal epileptiform activity can strengthen diagnosis, but a normal short recording does not sample every epileptogenic discharge.

Todd paresis has a clock

Temporary postictal weakness may follow a focal seizure, yet failure to improve demands urgent investigation for structural or vascular disease.

Video improves semiology

A safe witness recording can show eye state, asymmetry and responsiveness more accurately than retrospective labels such as fit.

One seizure is not epilepsy

Diagnosis depends on recurrent unprovoked seizures or a sufficiently high enduring recurrence risk, not the drama of one event.

Common pitfalls

  1. 01

    Diagnosing epilepsy solely because witnesses saw limb jerking.

  2. 02

    Using a normal routine EEG to exclude epilepsy.

  3. 03

    Ordering EEG for clear vasovagal syncope and overinterpreting incidental findings.

  4. 04

    Starting long-term treatment before classifying seizure type and recurrence risk.

  5. 05

    Missing cardiac warning features and omitting the ECG.

  6. 06

    Giving vague safety advice without a five-minute emergency threshold.

Practice

Two practice questions

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Question 1 of 2
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Paediatrics and child healthOriginal SBA

First diagnostic step

A 12-year-old has recovered fully after an unexplained collapse with brief stiffening. Witness details are incomplete and there is no fever. Which investigation belongs in the initial first-suspected-seizure assessment?

Choose one answer, then submit
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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.

  • NICE NG217 Epilepsies GuidelineFirst suspected seizure referral, ECG, EEG, imaging and treatment principles.
  • NICE NG127 Neurological RecognitionUrgent paediatric referral for seizures, weakness and neurological red flags.
  • NHS Epilepsy DiagnosisWitness history, diagnostic tests and practical patient information.
  • Resuscitation Council UK Paediatric Basic Life SupportCurrent paediatric airway, breathing and resuscitation support principles.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

NICE places diagnosis in specialist clinical assessment. A 12-lead ECG is part of first-seizure evaluation. EEG supports diagnosis and classification when the history suggests epilepsy; a normal EEG never rules it out, and indiscriminate EEG for probable syncope can create misleading incidental abnormalities. Sleep-deprived or ambulatory EEG is considered when uncertainty persists after routine testing.

Neuroimaging is driven by phenotype and urgency. MRI using an epilepsy protocol is preferred for non-acute structural assessment. Immediate CT may be justified by trauma, focal deficit, persistent depressed consciousness or concern for haemorrhage or mass effect. Blood tests are targeted to glucose, electrolytes, calcium, infection, toxicology or metabolic disease rather than ordered as a universal panel.

Long-term antiseizure treatment usually waits for paediatric neurology assessment after one unprovoked seizure. Earlier treatment may be considered when there is an unequivocal epileptic EEG, a structural neurological condition, a neurological deficit or a recurrence risk the family regards as unacceptable. Provide a written plan, school communication and clear thresholds for ambulance use while diagnostic work continues.

Key points

  • A first afebrile event is not automatically epilepsy; reconstruct exactly what happened before, during and after the episode from the child, witnesses and any video.
  • Stabilise first and check capillary glucose promptly when the child is still unwell, has not recovered or an acute metabolic cause is plausible.
  • NICE recommends urgent specialist assessment, usually within two weeks, after a first suspected seizure in a child or young person.
  • Obtain a 12-lead ECG after a first suspected seizure because arrhythmic syncope can produce stiffening and jerks that mimic epilepsy.
  • If the history supports epilepsy, EEG may support seizure classification but must not be used to exclude epilepsy; when requested after a first seizure, perform it as soon as possible, ideally within 72 hours.
  • MRI with an epilepsy protocol is the preferred structural study when indicated; emergency CT is reserved for an acute question such as trauma, haemorrhage or raised intracranial pressure.
  • Do not routinely start long-term antiseizure medicine after a single unprovoked seizure; specialist treatment depends on recurrence risk, EEG, neurological findings, imaging and family preference.
  • Teach seizure first aid: time the event, protect from hazards, cushion the head, do not
  • Exertional collapse, palpitations, family sudden death or a seizure-like event with little postictal confusion may represent a dangerous cardiac syncope.
  • Possible ingestion, diabetes, electrolyte loss, adrenal disease or metabolic disorder changes immediate glucose, blood and toxicology assessment.
  • A first seizure in an infant, a child with developmental regression or a child with a known brain lesion merits accelerated paediatric neurology review.
    • Epilepsy-protocol brain MRI
    Why
    Identify a congenital, neoplastic, vascular, inflammatory or acquired structural epileptogenic lesion.
    Interpretation and limitations
    MRI is preferred for planned structural evaluation; emergency CT answers selected acute questions but has lower lesion sensitivity.
  • 3Arrange ECG and only phenotype-directed blood, EEG and imaging investigations.
    • 03ReferUse the first-seizure pathwayClinical assessment supports a first suspected unprovoked seizure.+
    1. 1Arrange urgent paediatric specialist assessment within two weeks through the local pathway.
    2. 2Provide first-aid, school, water, height and emergency-call advice while diagnosis remains provisional.
    3. 3Record who will request and review EEG, MRI or cardiac assessment and how results reach the family.
    04Treat riskIndividualise recurrence preventionSpecialist assessment identifies a high recurrence risk or epilepsy.+
    1. 1Classify seizure type and syndrome before selecting an antiseizure medicine.
    2. 2Discuss likely benefit, adverse effects, reproductive safety and family priorities before starting treatment.
    3. 3Create an individual care plan covering rescue medication, follow-up, school and transition when appropriate.
    put anything in the mouth, place in recovery position when movements stop and call emergency help at five minutes.
  • Document driving implications only when age-relevant, but address bathing, swimming, heights, cycling and school supervision immediately and proportionately.
  • A normal examination and normal routine EEG reduce neither the importance of a convincing witness history nor the need for specialist review.