Status epilepticus

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Convulsive status epilepticus is a time-dependent neurological emergency. The practical management sequence has four parallel strands: terminate electrical and motor seizure activity, support airway and circulation, correct reversible causes, and prevent recurrence or secondary injury. Treatment times should be written on the resuscitation record because a vague sense of duration leads to both undertreatment and dangerous benzodiazepine accumulation.

First-line benzodiazepines enhance inhibitory GABA signalling but become less effective as status persists. After two appropriate doses, NICE recommends intravenous levetiracetam, phenytoin or sodium valproate as second-line options, with choice guided by contraindications, prior treatment, pregnancy and local familiarity. Phenytoin needs cardiac monitoring and controlled infusion; valproate carries major reproductive and hepatic constraints; levetiracetam has fewer acute interactions but still needs protocol-based dosing and renal consideration after stabilisation.

Non-convulsive status describes sustained electrographic seizure activity with altered cognition, behaviour or subtle motor signs rather than obvious generalised convulsions. It is particularly important after apparent convulsive cessation, in critical illness and in people with epilepsy who do not return to baseline. The current local adult or paediatric algorithm, resuscitation formulary, anaesthetic service and specialist advice determine exact doses and escalation.

Key points

Use the operational five-minute threshold because spontaneous termination becomes less likely and neuronal, respiratory, metabolic and systemic injury accumulates as convulsions continue.
Protect from injury, position and suction when feasible, give high-concentration oxygen if hypoxaemic, attach monitoring, obtain intravenous or intraosseous access and check capillary glucose immediately.
Give first-line benzodiazepine promptly: intravenous lorazepam when resuscitation facilities and access are available, or buccal midazolam or rectal diazepam when they are not, following the individual plan or local protocol.
If convulsions continue, a second benzodiazepine dose can be given after the protocol interval; after two adequate doses, move to intravenous levetiracetam, phenytoin or sodium valproate with expert guidance.
Do not let repeated small benzodiazepine doses consume the treatment window. Cumulative respiratory depression and failure to progress are common medication errors in prolonged seizures.
Refractory status persisting after an appropriate benzodiazepine and second-line medicine needs critical care, anaesthetic treatment and continuous EEG according to a specialist protocol.
Search for causes in parallel: non-adherence, stroke, infection, hypoglycaemia, sodium disturbance, alcohol or drug withdrawal, toxicity, eclampsia, trauma and autoimmune encephalitis all require mechanism-specific treatment.
For eclampsia, intravenous magnesium sulfate is the first-line anticonvulsant: use the obstetric regimen rather than substituting diazepam, phenytoin or a routine status-epilepticus load.
Persistent impaired consciousness after motor activity stops may be postictal, sedative-related or non-convulsive status; serial examination and urgent EEG help distinguish these pathways.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Established epilepsy and treatment interruption

Missed medicines, sleep loss, intercurrent illness or an ineffective regimen can permit seizures to continue or recur without recovery.

Acute structural brain injury

Stroke, haemorrhage, trauma, tumour and encephalitis can produce status as the first manifestation of cerebral disease.

Metabolic, toxic and withdrawal causes

Hypoglycaemia, sodium disturbance, organ failure, overdose and alcohol or sedative withdrawal destabilise cortical networks and require mechanism-specific correction.

Pregnancy-related disease

Eclampsia causes a distinct obstetric seizure emergency requiring simultaneous maternal stabilisation and pregnancy-specific seizure management through an obstetric pathway.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Persistent network recruitment
Excitatory cortical activity continues beyond normal self-termination and repeatedly recruits connected motor, autonomic and consciousness networks.
2
Inhibitory receptor failure
Sustained seizure activity internalises inhibitory receptors and strengthens excitation, making spontaneous cessation and later medicine response less likely.
3
Systemic physiological stress
Continuous muscle activity and impaired ventilation cause hypoxia, acidosis, hyperthermia, glucose disturbance and cardiovascular strain during prolonged seizures.
4
Neuronal injury
Prolonged excitotoxicity, inflammation and metabolic failure damage hippocampal and cortical neurons beyond the underlying cause during status epilepticus.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Convulsive statusRed flag

Continuous generalised convulsive activity at five minutes or recurrent convulsions without meaningful recovery meets the emergency treatment threshold and should be announced with elapsed time.

Subtle ongoing motor activityRed flag

Persistent eye deviation, eyelid twitching, facial jerks or rhythmic distal movement after major convulsions stop can represent continuing seizure activity rather than recovery.

Non-convulsive statusRed flag

Unexplained prolonged confusion, fluctuating responsiveness, behavioural change or coma, especially after a convulsion or in acute brain illness, warrants urgent EEG and neurological review.

Complicated physiologyRed flag

Hypoxia, hypercapnia, aspiration, hypotension, hyperthermia, acidosis, rhabdomyolysis and hyperkalaemia can emerge during prolonged convulsions and need concurrent resuscitative treatment.

Cause-specific emergencyRed flag

Fever with meningism, pregnancy-associated hypertension, focal deficit, head trauma, severe hyponatraemia or toxic exposure directs an additional time-critical pathway alongside seizure termination.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Capillary glucose and immediate physiological monitoringFirst step
Why
Detect a rapidly reversible cause and quantify respiratory and circulatory compromise during treatment.
Interpretation and limitations
Treat low glucose immediately according to protocol and consider thiamine where clinically indicated without delaying glucose. Pulse oximetry, ECG, blood pressure, temperature and capnography after airway intervention guide resuscitation.
02
Urgent blood sampling
Why
Identify electrolyte, infectious, toxic, hepatic, renal and medication-related precipitants and complications.
Interpretation and limitations
Send electrolytes including calcium and magnesium, renal and liver profiles, full blood count, inflammatory markers, blood gas, pregnancy test where relevant and antiseizure levels when actionable; do not await results before first-line therapy.
03
Emergency brain imaging
Why
Find haemorrhage, infarction, mass, trauma or another acute structural cause when the context requires it.
Interpretation and limitations
CT is often the immediate modality after stabilisation; vascular imaging and later MRI depend on focal signs and suspected mechanism. Imaging must not interrupt active seizure treatment or airway resuscitation.
04
Electroencephalography
Why
Confirm ongoing non-convulsive seizures, assess apparent refractory status and guide anaesthetic suppression.
Interpretation and limitations
Urgent or continuous EEG is particularly important when consciousness does not recover, paralysis masks motor activity or anaesthetic therapy is used. Findings require neurophysiology and clinical correlation.
05
Lumbar puncture and directed microbiology
Why
Investigate CNS infection or autoimmune inflammation after imaging and procedural safety have been assessed.
Interpretation and limitations
CSF sampling follows stabilisation and should not delay empiric antimicrobial or antiviral treatment when infection is strongly suspected. Tailor tests to age, immune status, travel and phenotype.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Functional prolonged seizure

Fluctuating asynchronous movement and preserved physiology may support a functional event, but emergency uncertainty requires skilled assessment without injurious repeated sedation.

Convulsive syncope

A hypoperfusion trigger, pallor and rapid recovery favour syncope; persistent convulsions or impaired consciousness require a seizure pathway.

Rigors or movement disorder

Shivering, dystonia and tremor preserve awareness and have different rhythmic or postural characteristics without a postictal phase.

Postictal state or non-convulsive status

Failure to recover after motor activity may reflect sedation or postictal suppression, but urgent EEG is needed when electrical seizures remain possible.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

010–10 minutesResuscitate and give benzodiazepineFirst stepA convulsive seizure reaches five minutes or repeats without recovery.

11. Call the emergency team, state seizure duration, protect airway and cervical spine as relevant, monitor ABCDE and check capillary glucose.
22. Give intravenous lorazepam if access and resuscitation facilities are present, otherwise use buccal midazolam or rectal diazepam according to plan and protocol.
33. Document drug, dose and exact time, reassess ventilation and circulation, obtain IV or IO access and send urgent cause-directed blood tests.
4Second line4. If seizure activity continues after the specified interval, give one further adequate benzodiazepine dose while preparing second-line therapy and critical-care support.

0210–30 minutesEscalate after two adequate dosesEscalationConvulsions continue despite two correctly delivered benzodiazepine treatments.

11. Obtain senior and anaesthetic help and select intravenous levetiracetam, phenytoin or sodium valproate using contraindications, prior medicine and local algorithm.
22. Infuse with the required ECG, blood-pressure and airway monitoring, avoiding an unsafe rate or a sequence of incomplete loading doses.
33. Continue cause treatment, including antimicrobials, electrolyte correction and toxicology measures; for eclampsia use the obstetric magnesium-sulfate regimen rather than substituting the routine status-epilepticus load.
4Second line4. Prepare for intubation, critical-care transfer and continuous EEG if electrical or clinical seizure activity persists after the second-line load.

03RefractoryControl seizures in critical careSecond lineStatus continues after a benzodiazepine and an appropriate second-line intravenous antiseizure medicine.

11. Secure the airway and use anaesthetic seizure suppression under critical-care and neurology leadership with continuous cardiorespiratory monitoring.
22. Start continuous EEG to confirm electrographic control and guide depth and duration of therapy, particularly when neuromuscular blockade removes visible movement.
33. Re-examine the cause for infection, autoimmune encephalitis, toxin, metabolic disease, structural injury and missed or insufficient maintenance treatment.
44. Plan maintenance antiseizure therapy, weaning, complication surveillance and post-event communication once control is achieved.

Key medicines and prescribing safety5 treatments · regimens, roles and cautions

First-line hospital treatment for convulsive status when intravenous access and resuscitation facilities are immediately available.

Intravenous lorazepam

A common adult protocol uses 0.1 mg/kg intravenously up to 4 mg, with one repeat dose after 5–10 minutes if convulsions continue; use the current local algorithm.

Monitor airway, respiratory rate, oxygenation and blood pressure. Count pre-hospital benzodiazepines before repeating, and do not postpone second-line treatment through serial subtherapeutic dosing.

One NICE-listed second-line option for established convulsive status, with relatively few acute pharmacokinetic interactions.

Intravenous levetiracetam

Many UK emergency protocols use 60 mg/kg up to 4.5 g infused over about 10 minutes after two benzodiazepine doses; confirm dose and infusion with the local formulary.

Do not delay airway escalation while it infuses. Record renal impairment for subsequent maintenance adjustment and monitor sedation, agitation and clinical or electrographic seizure persistence.

Alternative second-line treatment with long clinical experience, particularly when the seizure and patient context favour a sodium-channel option.

Intravenous phenytoin

A typical adult loading regimen is 20 mg/kg up to 2 g, usually no faster than 50 mg/min, using continuous ECG and blood-pressure monitoring under the local protocol.

Avoid or seek specialist alternatives in significant conduction disease, bradycardia or hypotension. Extravasation can injure tissue, interactions are extensive, and it may aggravate some generalised epilepsies.

Broad-spectrum second-line option that may be useful when phenytoin is unsuitable and the seizure syndrome supports it.

Intravenous sodium valproate

Some emergency algorithms use 40 mg/kg up to 3 g as a controlled intravenous load; prescribing must comply with current MHRA restrictions and specialist or emergency protocol.

Avoid in known significant liver disease, mitochondrial disorder and pregnancy unless the emergency specialist balance leaves no suitable alternative. Apply reproductive-risk safeguards after stabilisation.

First-line anticonvulsant treatment for an eclamptic fit; routine diazepam, phenytoin or other anticonvulsants must not be substituted for magnesium sulfate.

Intravenous magnesium sulfate for eclampsia

Use the NICE obstetric regimen: 4 g intravenously over 5–15 minutes, then 1 g/hour for 24 hours; if seizures recur, give a further 2–4 g intravenously over 5–15 minutes under the obstetric emergency protocol.

Involve obstetrics, anaesthesia and critical care. Renal impairment increases accumulation risk; follow the obstetric protocol for adjustment and monitor respiration, oxygenation, tendon reflexes, urine output and renal function, with calcium gluconate available for toxicity treatment.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Hypoxia and aspiration

Loss of airway control, secretion, vomiting and respiratory depression cause pneumonia, hypoxic injury and arrest during convulsions.

Permanent neuronal injury

Continuing excitotoxic and metabolic stress can leave lasting cognitive, memory and focal neurological disability or cause death.

Rhabdomyolysis and renal injury

Sustained convulsions generate heat, muscle breakdown, electrolyte disturbance and myoglobin-related kidney damage during prolonged generalised convulsions.

Treatment-related cardiorespiratory harm

Cumulative benzodiazepines, anaesthesia and intravenous antiseizure medicines can cause hypotension, arrhythmia and respiratory failure during escalation.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Use a visible timeline documenting clinical seizure onset, every rescue and loading dose, response, airway intervention and recurrence so treatment stages are not repeated or missed.
Continuously monitor oxygenation, ECG and blood pressure during active status and second-line infusion, adding capnography when ventilation is assisted or the airway secured.
Repeat glucose, blood gas, electrolytes, temperature, renal function and creatine kinase according to duration and physiology, watching for aspiration and rhabdomyolysis.
Assess recovery of consciousness and focal neurology serially; absent recovery should trigger EEG and renewed structural, infectious, toxic and medication review.
After control, reconcile usual antiseizure medicines, adherence and levels where meaningful, then provide an updated emergency plan and specialist follow-up.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

The clock is a treatment

Explicitly announcing five, ten and subsequent elapsed minutes reduces therapeutic drift and helps the team prepare the next drug before failure is confirmed.

Motor cessation may deceive

Visible convulsions can stop while electrographic seizure activity continues, especially after paralytic or sedative treatment, making EEG central in refractory cases.

Benzodiazepine history matters

Ambulance, carer and emergency-department doses are cumulative; accurate handover prevents both needless repetition and the mistaken belief that two adequate doses were given.

Second-line options are contextual

Similar average efficacy does not make levetiracetam, phenytoin and valproate interchangeable for a person with arrhythmia, pregnancy, liver disease or a particular epilepsy syndrome.

Postictal is a diagnosis under review

Sedation and a genuine postictal state are common, but persistent coma should never be assumed benign before non-convulsive status and acute brain disease are considered.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for venous access when buccal or rectal rescue treatment is immediately available loses time during continuing neuronal and systemic stress.
02
Giving many undocumented benzodiazepine increments increases respiratory depression while obscuring whether the protocol threshold for second-line treatment has been met.
03
Infusing phenytoin without ECG and blood-pressure monitoring risks avoidable hypotension and dysrhythmia.
04
Stopping the diagnostic work once convulsions cease can miss meningitis, stroke, eclampsia, intoxication or severe electrolyte disease that will provoke recurrence.
05
Assuming an unresponsive paralysed patient is seizure-free without EEG can leave refractory electrographic status untreated.