Seizures and epilepsy

• An epileptic seizure is a transient burst of abnormal, synchronised activity in a group of cortical neurones; epilepsy is the enduring tendency of the brain to produce such seizures.
• The ILAE 2017 classification divides seizures by onset (focal, generalised, unknown) and by whether awareness is preserved; focal seizures can spread to both sides and look generalised.
• A single seizure is not epilepsy. Epilepsy is usually diagnosed after two unprovoked seizures more than 24 hours apart, or after one unprovoked seizure when the risk of recurrence is high. ^[9]
• Treatment is chosen by seizure type and syndrome: for example, ethosuximide first for absence seizures, and lamotrigine or levetiracetam first for focal seizures, per NICE NG217.
• For women and girls who may become pregnant, sodium valproate and topiramate carry pregnancy prevention requirements, because both are teratogenic.
• Driving rules differ by country; in the UK a person with epilepsy generally must be seizure-free for 12 months before driving a car. ^[9]
• Surgery and neuromodulation are genuine options for drug-resistant epilepsy, and SUDEP risk can be reduced by keeping seizures controlled. ^[7]

By the end of this page you should be able to:

1. Define seizure and epilepsy and explain how a seizure differs from syncope or a functional event.
2. Use the ILAE 2017 classification to label a seizure as focal, generalised, or unknown onset and say what "focal to bilateral tonic-clonic" means.
3. Distinguish provoked from unprovoked seizures and explain why that distinction matters for treatment and driving.
4. Plan the assessment after a first suspected seizure: history, ECG, EEG, MRI, and when each is indicated.
5. Match first-line and add-on antiseizure medications to seizure type and identify the drugs that worsen absence or myoclonic seizures. ^[4]
6. Apply the safety rules for women, men, older adults and people with multimorbidity, and counsel on driving.
7. Explain the surgical and non-pharmacological options for drug-resistant epilepsy and the NICE criteria for referral.
8. List the complications, prognosis and SUDEP risk factors, and the prevention and screening points that matter most.

The ILAE's practical definition also recognises epilepsy when the brain shows an epileptogenic abnormality and one unprovoked seizure has occurred. A person who has had a stroke, a brain infection or a birth injury can therefore meet the diagnosis before a second seizure.

The ILAE revised the operational classification of seizure types in 2017 to make onset (where the electrical storm starts) central, to allow "unknown onset" when the beginning was not witnessed, and to use clearer names. ^[1]

The 2017 classification has two versions: a Basic version for general use and an Expanded version for specialists. ^[1]

In the Expanded version the same framework is filled in with named subtypes. Focal onset now replaces the older terms "simple partial" and "complex partial". "Focal impaired awareness seizure" replaces "complex partial seizure"; "focal aware seizure" replaces "simple partial". "Focal to bilateral tonic-clonic" replaces "secondarily generalised tonic-clonic". Awareness may be impaired at any point during the seizure. A focal seizure that evolves into a bilateral tonic-clonic convulsion should still be classified as focal onset, because the origin was focal.

The ILAE classification of the epilepsies groups epilepsies by mode of onset (focal, generalised, combined generalised and focal, unknown), by aetiology (genetic, structural, metabolic, immune, infectious, unknown) and by syndrome. Naming the syndrome matters because it changes treatment and prognosis.

The distinction is not always clean; some events sit in between, such as a first seizure with sleep deprivation and alcohol. The pragmatic question is whether there is an acute reversible precipitant and whether the brain has an enduring predisposition. ^[9]

A first unprovoked seizure in a child carries a recurrence risk concentrated in the first 6 to 12 months. NICE recommends starting an antiseizure medication after a first unprovoked seizure when there is a neurological deficit on examination, unequivocal epileptic activity on EEG, a structural abnormality on brain imaging, or when the person and their family decide the risk is unacceptable. ^{[3] [2]}

Exact global prevalence depends on case definition, but epilepsy is among the most common serious neurological disorders. In many low- and middle-income settings structural epilepsy is proportionally more common than in high-income settings, because perinatal injury, central nervous system infection and parasitic disease are more frequent there.

Risk factors for a first unprovoked seizure or for epilepsy developing include previous brain injury, central nervous system infection, stroke, brain tumour, malformation of cortical development, hippocampal sclerosis, genetic predisposition and the complications of birth injury. ^[6] In adults, vascular risk factors (diabetes, hypertension, atrial fibrillation) and mental health problems (depression, anxiety, psychosis, substance misuse) are modifiable factors that can raise the risk of a further seizure. ^[2] Sepsis also increases risk. ^[2]

A seizure is the final common pathway of excessive neuronal excitation or failed inhibition. The aetiology can be grouped in the ILAE 2017 framework:

• Genetic (or presumed genetic). Channelopathies and polygenic predisposition, notably in idiopathic generalised epilepsies. Family history matters more in childhood-onset syndromes.
• Structural. Stroke, traumatic brain injury, hippocampal sclerosis, malformations of cortical development, brain tumours, vascular malformations, and post-infectious or post-surgical scarring.
• Metabolic. Hypoglycaemia, hepatic or renal failure, electrolyte disturbance, inborn errors of metabolism, especially in neonates and infants.
• Immune. Autoimmune encephalitis, for example anti-NMDA receptor or anti-LGI1 antibody disease.
• Infectious. Meningitis, encephalitis, neurocysticercosis, malaria, HIV.
• Unknown. Still the largest group in adults in many series.

A seizure arises when the balance between excitation (mainly glutamate) and inhibition (mainly GABA) in cortical networks tips towards runaway synchronous discharge. Normal cortex can produce a seizure if enough excitatory drive is applied or enough inhibition is removed; epileptic cortex has a lowered threshold.

Focal seizures begin in a local network and can remain local or spread. Generalised seizures engage both hemispheres from the outset, often via thalamocortical circuits. Focal seizures that spread to both hemispheres produce focal to bilateral tonic-clonic seizures, which look identical to generalised tonic-clonic seizures clinically and cannot be distinguished without a witness account of the onset or an ictal EEG. That distinction matters: the management of focal onset and generalised onset epilepsy differs.

During a tonic-clonic seizure the typical sequence is tonic stiffening (rigid extension, often with a cry from forced expiration), then clonic jerking, then a post-ictal state with confusion, headache and sleepiness. A focal impaired awareness seizure may appear as arrest of activity, automatisms such as lip-smacking, or wandering; the person is usually unaware and amnesic afterwards. Absence seizures are brief lapses, often in children.

Status epilepticus is a seizure lasting 5 minutes or more, or repeated seizures without recovery between them. ^[5]

A first seizure is diagnosed from the story; tests rarely make the diagnosis on their own. The history should capture:

• The account of an eyewitness, or video, if available. What happened first, in what order, and how it ended.
• Duration of the whole event and of each phase.
• Whether awareness was present or lost at any point.
• Automatisms, motor phenomena, vocalisation, autonomic symptoms (pallor, flushing, nausea, incontinence), and the post-ictal period.
• Precipitants: sleep deprivation, alcohol, fever, photic stimulation, menstruation, hormonal change, medication changes, missed doses.
• Past medical, birth and developmental history, head injury, infections, stroke, and family history of seizures.
• Medications, including over-the-counter drugs and recreational drugs.

A physical examination may be normal between seizures. Look for:

• A focal neurological deficit that might betray the seizure origin or an underlying lesion.
• Signs of head injury, tongue biting, or other injury.
• Skin and neurocutaneous signs (hypopigmented macules, neurofibromas, port-wine stain, cafe-au-lait spots) suggesting neurocutaneous disease.
• Cardiovascular findings: an arrhythmia or a murmur that could be a mimic rather than epilepsy.

The first question is whether the event was an epileptic seizure at all; the second is which seizure type or mimic.

NICE NG217 structures the assessment after a first suspected seizure. ^[2]

MRI is not required for people with idiopathic generalised epilepsy or self-limited epilepsy with centrotemporal spikes. Repeat scanning is considered when the first scan was suboptimal, when seizures continue despite treatment, or when surgery is being considered. A CT scan is not needed for a person with established epilepsy presenting to an emergency department after a typical seizure, unless there are other concerns. ^[2]

An EEG supports the diagnosis and helps classify the syndrome, but a normal EEG never excludes epilepsy. ^[2]

Epilepsy is a clinical diagnosis. The criteria rest on a combination of history, EEG and imaging rather than on one test:

• Two unprovoked seizures more than 24 hours apart; or ^[9]
• One unprovoked seizure with an EEG or imaging abnormality that predicts a recurrence risk comparable to two seizures; or
• A recognised epilepsy syndrome.

Epilepsy should be diagnosed and treatment started once the diagnosis is confirmed. Review the diagnosis if seizures continue despite an optimal dose of a first-line antiseizure medication. ^[3] The diagnosis is made by a clinician with expertise in first seizures and epilepsy; urgent referral after a first suspected seizure should be for an appointment within 2 weeks. ^[2]

• Use monotherapy with one antiseizure medication whenever possible. ^[3]
• Start an antiseizure medication once epilepsy is confirmed; consider it after a first unprovoked seizure if the criteria above are met. ^[3]
• Individualise the choice: seizure type, syndrome, age, sex, comorbidity, other medications, pregnancy plans, education, employment and driving all matter. ^[3]
• Review the diagnosis if the first drug at an adequate dose does not help. ^[3]
• In older people, check interactions, start low and titrate slowly. ^[3]

Doses are not given here; they must be titrated against the British National Formulary or local formulary, weight, renal and hepatic function, and the person's response.

Generalised tonic-clonic seizures. First-line monotherapy: lamotrigine, levetiracetam or sodium valproate (with valproate pregnancy precautions). ^[4] If monotherapy fails, add (in priority order): clobazam, lamotrigine, levetiracetam, perampanel, sodium valproate, topiramate (with topiramate pregnancy precautions). ^[4] Second-line add-ons include brivaracetam, lacosamide, phenobarbital, primidone and zonisamide. ^[4]

Focal seizures (with or without evolution to bilateral tonic-clonic). First-line monotherapy: lamotrigine or levetiracetam. ^[4] Second-line monotherapy: carbamazepine, oxcarbazepine or zonisamide; third-line: lacosamide. ^[4] First-line add-ons include carbamazepine, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, topiramate (with pregnancy precautions) and zonisamide. ^[4]

Absence seizures. First-line: ethosuximide. ^[4] Second-line (monotherapy or add-on): lamotrigine, levetiracetam or sodium valproate (with valproate precautions). ^[4] If absence occurs with other seizure types, first-line is lamotrigine, levetiracetam or sodium valproate, with ethosuximide as a second-line add-on. ^[4]

Myoclonic seizures. First-line: levetiracetam or sodium valproate (with precautions). ^[4] Second-line options include brivaracetam, clobazam, clonazepam, lamotrigine, phenobarbital, piracetam, topiramate (with precautions) and zonisamide. ^[4]

Tonic or atonic seizures. First-line: lamotrigine or sodium valproate (with precautions). ^[4] Second-line: clobazam, rufinamide or topiramate (with precautions); ketogenic diet if seizures persist; felbamate as a last resort. ^[4]

Idiopathic generalised epilepsies. First-line: lamotrigine, levetiracetam or sodium valproate (with precautions). ^[4] Second-line add-ons: perampanel or topiramate (with precautions). ^[4]

• Status epilepticus is seizures lasting 5 minutes or more; it is a medical emergency. Resuscitate, give a benzodiazepine first-line (buccal midazolam or rectal diazepam in the community; intravenous lorazepam if intravenous access and resuscitation are available), and call emergency services. ^[5]
• If two benzodiazepine doses fail, give levetiracetam, phenytoin or sodium valproate intravenously as second-line treatment. ^[5]
• Third-line: phenobarbital or general anaesthesia under expert guidance. ^[5]
• Repeated or cluster seizures (typically 3 or more self-terminating seizures in 24 hours) and prolonged seizures (more than 2 minutes longer than the person's usual seizure) are also emergencies. ^[5]
• Non-epileptic (dissociative) seizures can mimic convulsive status epilepticus; consider the diagnosis. ^[5]

• Common: sedation, dizziness, cognitive slowing, mood change (levetiracetam), weight change, gastrointestinal upset, tremor.
• Serious hypersensitivity and skin reactions occur with several agents: phenytoin carries higher risk in people of Han Chinese or Thai background; carbamazepine and chemically related drugs (oxcarbazepine, eslicarbazepine acetate) in Han Chinese, Thai, European and Japanese backgrounds. ^[3]
• Long-term treatment with carbamazepine, phenytoin, primidone or sodium valproate is associated with decreased bone mineral density and osteomalacia; consider calcium and vitamin D in those at risk. ^[3]
• Carbamazepine, oxcarbazepine, phenytoin and topiramate can impair the effectiveness of hormonal contraceptives; oestrogen-containing contraceptives and HRT can impair the effectiveness of lamotrigine. ^[3]
• Valproate warnings apply to men as well as women: possible association with neurodevelopmental disorders in children conceived while the father is taking valproate, and possible fertility effects. ^[3]

Drug-resistant epilepsy is failure to achieve seizure freedom after adequate treatment with antiseizure medication. Such patients should be referred to a tertiary epilepsy service for assessment, including resective surgery. ^[6]

• Resective surgery. For focal epilepsies with a clear, resectable focus, particularly those with hippocampal sclerosis, malformation of cortical development, epilepsy-associated low-grade tumours, hypothalamic hamartoma, neuronal migrational disorder, tuberous sclerosis complex, vascular malformation (including Sturge-Weber), cerebral contusion, or no MRI abnormality but a good electroclinical picture. ^[6] Do not exclude people with learning disability or a genetic abnormality from referral. ^[6]
• Vagus nerve stimulation. Consider as an add-on if resective surgery is not suitable. ^[6]
• Ketogenic diet. Under a specialist team, for certain childhood-onset syndromes or drug-resistant epilepsy when other options have failed. ^[6]
• Non-pharmacological care always runs alongside antiseizure medication, not instead of it.

• Review adults with epilepsy at least annually if they have a learning disability, drug-resistant epilepsy, high SUDEP risk, serious comorbidity, or are taking sodium valproate or other drugs with long-term effects or interactions; children and young people at least every 12 months, tailored to need. ^[3]
• After 2 years seizure-free, carry out an individualised assessment before withdrawing antiseizure medication. Reducing over at least 3 months is typical, and medications are withdrawn one at a time. ^[3]
• If seizures recur during or after withdrawal, reverse the last reduction and seek specialist advice. ^[3]
• After epilepsy surgery, withdrawal is guided by the surgery centre. ^[3]
• Medication should not be withdrawn while the person is driving; effective advice must be given. ^[9]

• Injury. Tongue biting, fractures, burns and drowning risk; head injury from falls.
• Status epilepticus. A medical emergency with mortality.
• Cognitive and behavioural problems. Memory and attention problems in people with frequent seizures; psychiatric comorbidity is common and should be screened for.
• SUDEP. Sudden unexpected death in epilepsy; risk factors include generalised tonic-clonic seizures, uncontrolled seizures, nocturnal seizures, non-adherence to medication, living or sleeping alone, and alcohol or drug misuse. ^[7]
• Medication-related harm. Teratogenicity (valproate, topiramate), reduced bone density, serious skin reactions, and drug interactions.
• Social. Stigma, employment and driving restrictions, and impact on education and relationships.

Prognosis depends on seizure type, syndrome, cause and response to treatment. Many syndromes of childhood are self-limited; drug-resistant focal epilepsy can still be improved by surgery. Some people become seizure-free on the first appropriate drug, and others respond to a second drug or to combination therapy.

The recurrence risk in children after a first unprovoked seizure is highest in the first 6 to 12 months and is raised by an abnormal EEG or imaging and by a neurological deficit. ^[2] After 2 years seizure-free on medication, an individualised decision can be made about withdrawal, with recurrence risk assessment. ^[3]

• Treat the cause where possible: stroke prevention, infection control and birth injury prevention all reduce epilepsy incidence.
• Antiseizure medication should not be stopped abruptly, because rebound seizures and status epilepticus can follow.
• Screening for seizure-related death risk starts at diagnosis: discuss SUDEP and the modifiable risk factors, including medication adherence, alcohol misuse and nocturnal safety. ^[7]
• Night-time supervision (alarms, shared sleeping) can be considered for people assessed as higher risk who have nocturnal seizures. ^[7]
• Bone health: consider calcium and vitamin D for people at risk of reduced bone density. ^[3]
• Women of childbearing age need a documented discussion of the risks of antiseizure medications in pregnancy, and review before conception. ^[3][8]

• Women and girls with epilepsy who are planning pregnancy or are pregnant should be referred to an epilepsy specialist team, with care shared between epilepsy and obstetric teams. ^[3]
• They should not stop medication without medical supervision. ^[3]
• Valproate carries the greatest teratogenic risk among the older antiseizure medications: higher than carbamazepine in terms of major congenital malformations, and it reduces cognitive outcomes in exposed children. ^[8]
• Valproate is associated with neural tube defects and facial clefts; phenytoin with cleft palate; phenobarbital with cardiac malformations in some studies. ^[8]
• Risk rises with dose, particularly above about 1,000 mg daily of valproate in several studies, and with polytherapy; limiting the dose where possible should be considered. ^[8]
• Avoiding valproate and polytherapy in the first trimester should be considered to reduce major congenital malformations; avoiding valproate and polytherapy throughout pregnancy should be considered to protect cognitive outcomes. ^[8]
• Lamotrigine and carbamazepine are comparatively safer in pregnancy according to the same review. ^[8]
• Carbamazepine, lamotrigine, levetiracetam, oxcarbazepine, phenobarbital and phenytoin levels should be checked and doses adjusted through pregnancy under MHRA advice; doses usually return to pre-conception levels in the first few days after birth. ^[3]
• Breastfeeding is generally safe with most antiseizure medications and should be encouraged; individual drug advice in the summary of product characteristics and formulary should be followed. ^[3]
• Folic acid supplementation, contraception, menopause and caring for children should be reviewed regularly as part of care. ^[3]

Childhood epilepsy syndromes are recognisable electroclinical patterns: age at onset, seizure type and EEG features define them, and naming the syndrome changes drug choice. Cross-check the paediatrics topic "Childhood epilepsy syndromes": infantile spasms, childhood absence epilepsy, self-limited epilepsy with centrotemporal spikes, Lennox-Gastaut syndrome, and febrile seizures. The general ladders on this page for generalised tonic-clonic, focal, absence, myoclonic and tonic or atonic seizures are the same starting point, but syndrome-specific cautions are listed in that topic. EEG is requested early, ideally within 72 hours of a first seizure, and MRI within 6 weeks unless the child has idiopathic generalised epilepsy or self-limited centrotemporal spikes. ^[2]

Older people starting medication need interaction checks, low starting doses and slow titration, particularly with comorbidity and polypharmacy. ^[3] New-onset epilepsy in an older adult should prompt brain imaging to look for a structural cause.

Men taking valproate who are planning a family within the next year should be referred to an epilepsy specialist team to review options, because of a possible association with neurodevelopmental disorders in offspring and possible fertility effects. ^[3]

Rules are national and the following are the UK DVLA position. ^[9]

• Epilepsy in driving law means two or more unprovoked seizures within five years.
• A person with epilepsy or multiple unprovoked seizures must not drive and must notify the DVLA; driving generally ceases for 12 months from the most recent seizure.
• After a first unprovoked seizure, driving usually ceases for 6 months, or 12 months if there is an underlying cause that may increase risk. ^[9]
• Provoked seizures usually stop driving for 6 months in most cases.
• Sleep-only seizures follow special rules: a year off driving, or licensing if only-ever-asleep seizures are established for at least 3 years. ^[9]
• Anti-epilepsy medication should not be withdrawn while the person is driving, and individuals should not drive during withdrawal or for 6 months after the last dose; earlier relicensing may follow a substitution with specialist advice. ^[9]
• Bus and lorry drivers must usually be seizure-free and off anti-epileptic medication for 10 years. ^[9]
• People taking medication must be compliant, and the DVLA must be told about any seizure.

• A clinical history, 12-lead ECG and blood glucose can be obtained almost anywhere; a routine EEG and MRI are arranged where available.
• First-line antiseizure medicines listed here include older, inexpensive drugs (carbamazepine, phenytoin, sodium valproate, phenobarbital) that are available in most settings, although some carry serious safety warnings.
• Surgery and neuromodulation need referral to a tertiary centre; where they are unavailable, optimise medical therapy and safety.
• Practical seizure-safety measures (showering not bathing alone, avoiding heights and machinery, safe cooking arrangements) cost little and matter a lot.
• Telling families when to seek urgent care, and how to give rescue benzodiazepine for prolonged seizures, prevents harm.

• A seizure is a symptom; epilepsy is the enduring predisposition to recurrent unprovoked seizures.
• ILAE 2017 classifies seizures by onset (focal, generalised, unknown) and by whether awareness is preserved; focal seizures can spread and look generalised.
• The epilepsy versus mimic distinction rests on the history, ideally with a witness or video.
• After a first suspected seizure: ECG now, EEG ideally within 72 hours, MRI within 6 weeks unless idiopathic generalised or self-limited centrotemporal spikes. ^[2]
• First-line choices by type: generalised tonic-clonic lamotrigine, levetiracetam or valproate; focal lamotrigine or levetiracetam; absence ethosuximide; myoclonic levetiracetam or valproate; tonic or atonic lamotrigine or valproate.
• Carbamazepine, oxcarbazepine, phenytoin and similar drugs can worsen absence and myoclonic seizures.
• Valproate and topiramate are teratogenic and carry pregnancy prevention requirements; women need pre-conception planning, and breastfeeding is generally safe.
• Surgery referral is appropriate for drug-resistant epilepsy, including many cases with a clear MRI lesion or a good electroclinical picture.
• SUDEP risk is reduced by taking medication, controlling generalised tonic-clonic seizures, and avoiding sleeping alone where possible.
• UK driving generally requires 12 months seizure-free for people with epilepsy, with different rules for a first or provoked seizure and for vocational licences.

• Febrile seizures
• Childhood epilepsy syndromes
• Neonatal seizures and hypoxic-ischaemic encephalopathy
• Headache and migraine
• Syncope
• Stroke and transient ischaemic attack
• Meningitis and encephalitis
• Traumatic brain injury
• Intellectual disability and developmental delay