Seizure Types Explained: Focal, Generalised and the Rest

Seizure types explained: what you are actually looking at

Most people can recognise one seizure type. It is the tonic-clonic — the person falls, stiffens, convulses, and is confused afterwards. It is dramatic, it is the one in films, and it is a minority of seizures.

The ones that get missed are the others: thirty seconds of staring that looks like daydreaming, a strange rising feeling in the stomach that nobody else can see, a hand picking at clothing while the person seems vaguely present, a single violent jerk on waking, a head drop that looks like a stumble.

Those matter for three reasons. They are seizures, so they count towards diagnosis and towards driving rules. They tell a neurologist where in the brain the problem is, which is the single most useful piece of information for choosing treatment. And some of them get treated as behaviour, inattention or clumsiness for years — particularly in children and particularly in people with intellectual disability, where a change in presentation tends to be attributed to the disability rather than investigated.

This guide covers the current classification, what each seizure type actually looks like from outside, what the person experiences from inside, and what is worth recording. Seizure first aid and management plans are covered in the practical guide, epilepsy and seizure support.

The structure of the classification

The International League Against Epilepsy revised seizure classification in 2017 and the terminology changed, which is why older material uses different words. Three questions determine the label.

Where did it start? Focal seizures begin in one area of one hemisphere. Generalised seizures involve networks on both sides from the outset. Where onset cannot be determined, the seizure is classified as unknown onset.

Was awareness affected? For focal seizures, this is the key second question. Focal aware means the person knows what is happening and can recall it. Focal impaired awareness means they cannot. Awareness, not consciousness, and not responsiveness — somebody can be unresponsive but aware, and the distinction is made on whether they can recall the event.

What did the body do? Motor or non-motor features, with specific descriptors.

The old terms and their replacements, because you will encounter both:

And one term worth retiring properly: “aura.” What people call an aura is itself a focal aware seizure — the beginning of a seizure, not a warning before one. That matters because it means an aura counts as a seizure event, including for driving purposes, and because the nature of the aura tells a neurologist precisely where the seizure starts.

Focal seizures

Focal seizures are the most common type in adults and the most varied, because what happens depends entirely on which part of the brain is involved.

Focal aware seizures

The person remains aware and can usually describe it afterwards. They last seconds to a couple of minutes. What they consist of depends on the location:

Temporal lobe onset, the commonest: a rising sensation in the stomach, often described as a wave or a feeling of something climbing upwards. An intense feeling of familiarity (déjà vu) or unfamiliarity. A smell or taste nobody else detects, frequently unpleasant — burning rubber, metal. A sudden overwhelming fear with no cause. A feeling of detachment or unreality. Sometimes an intense pleasant or spiritual sensation.

Frontal lobe onset: stiffening or jerking of one limb, head or eye turning to one side, odd posturing of an arm, sometimes speech arrest.

Parietal lobe onset: tingling, numbness, a sensation of movement in a limb, or distortion of body perception.

Occipital lobe onset: coloured shapes, flashing lights, loss of part of the visual field, or the sensation of eyes being pulled to one side.

The Jacksonian march, where jerking or tingling begins in one place — a thumb, a corner of the mouth — and spreads progressively up the limb or across the face as the seizure moves across the motor strip.

What makes these hard to recognise. They are entirely internal in many cases. People describe having had them for years before telling anybody, because they assumed everybody experienced them, or because describing them sounds strange. A person who says “sometimes I get a weird feeling and then a few minutes go missing” is describing a focal aware seizure progressing to a focal impaired awareness seizure, and that is a diagnosis waiting to be made.

Focal impaired awareness seizures

The person’s awareness is affected. They do not recall the event, or recall only its beginning. These usually last one to three minutes, and the recovery period afterwards can run considerably longer.

What it looks like from outside:

• A blank or glazed expression, staring
• Automatisms — repetitive, purposeless movements. Lip smacking, chewing, swallowing, picking at clothes or objects, fumbling with hands, rubbing, fiddling
• Repeating a word or phrase, or mumbling
• Wandering, sometimes walking somewhere with apparent purpose
• Undressing or fiddling with clothing
• Unresponsive, or responding oddly and inappropriately
• Sometimes a dystonic posture of one arm, which is a useful lateralising sign

Afterwards: confusion, tiredness, sometimes a headache, sometimes a period of difficulty finding words, and no memory of the event. Recovery can take minutes to an hour or more.

Why these get missed. They look like daydreaming, drunkenness, confusion, a psychiatric episode, or simply someone being odd for a minute. People get stopped by police, asked to leave shops, and assumed to be intoxicated. In a care setting they get recorded as “a bit vague this afternoon.”

Focal to bilateral tonic-clonic seizures

A focal seizure that spreads to both hemispheres and becomes a convulsion. Formerly called secondary generalisation.

Why the distinction from a primary generalised tonic-clonic matters enormously: it means the epilepsy is focal, there may be a structural cause on MRI, and it may be surgically treatable. Whether anybody noticed the focal beginning is therefore clinically important, which is why witnesses are asked what happened in the first few seconds.

Generalised seizures

These involve both hemispheres from the start, so awareness is affected from the outset.

Tonic-clonic seizures

The one everybody recognises.

What happens: sometimes a cry as air is forced out, then loss of consciousness and a fall. The tonic phase — the whole body stiffens, lasting seconds — followed by the clonic phase, rhythmic jerking of the limbs, gradually slowing. Breathing is irregular and the person may go blue around the lips. The tongue or cheek may be bitten. There may be incontinence. The seizure itself usually lasts one to three minutes.

Afterwards, and this is the part families find hardest: deep sleep, confusion, headache, muscle aches, sometimes vomiting, sometimes agitation or distress on waking. The recovery period can last from minutes to many hours, and it is not unusual for somebody to be out of action for the rest of the day.

The five-minute rule. A tonic-clonic seizure lasting more than five minutes, or repeated seizures without recovery in between, is a medical emergency — call 000. This is the threshold at which status epilepticus is considered and at which emergency medication, if prescribed, is given.

And one correction worth stating: never put anything in the mouth of somebody having a seizure. It does not prevent tongue biting and it causes injury.

Absence seizures

Brief lapses of awareness, lasting usually five to twenty seconds.

What it looks like: a sudden stop mid-sentence or mid-activity. Staring. Eyelid fluttering in some people. Sometimes very subtle automatisms — a small lip movement, a slight hand movement. Then an equally sudden return, with no confusion and frequently no awareness that anything happened.

What distinguishes absence from focal impaired awareness seizures: absences are shorter, there is no warning, there is no confusion afterwards, and they can occur many times a day — dozens or hundreds in childhood absence epilepsy.

Why they get missed for years. They look exactly like inattention, and a child having forty absences a day is a child who appears not to be listening, is falling behind at school, and gets described as dreamy or oppositional. Hyperventilation during an EEG will often provoke one, which is how the diagnosis is confirmed.

And the treatment point: absences respond to specific medications and are made worse by others. Carbamazepine, which is good for focal seizures, can aggravate absences. Getting the seizure type right is what prevents that.

Myoclonic seizures

Sudden brief shock-like jerks, usually of the arms and shoulders, sometimes the whole body. Single or in clusters. Awareness is preserved.

The classic pattern is in juvenile myoclonic epilepsy: jerks in the first hour or two after waking, often described as dropping the cereal bowl or throwing the toothbrush, frequently for months or years before a tonic-clonic seizure finally brings the person to a doctor. Sleep deprivation and alcohol are strong provoking factors, which is why this diagnosis often announces itself after a late night.

Tonic seizures

Sudden stiffening of the body, usually brief, frequently causing a fall backwards. Common in the developmental and epileptic encephalopathies and frequently nocturnal.

Atonic seizures

A sudden loss of muscle tone — the “drop attack.” The person’s head drops, or their legs give way, and they fall, usually forwards. They last seconds and recovery is immediate.

These cause more injury than any other seizure type, because there is no warning and no protective reaction. Facial and dental injury is common, and protective headgear is sometimes used. Atonic seizures are a hallmark of Lennox-Gastaut syndrome.

Epileptic spasms

Brief symmetrical contractions, typically of the neck, trunk and limbs, occurring in clusters and most often in infancy. Infantile epileptic spasms syndrome (formerly West syndrome) is a developmental and epileptic encephalopathy, and it is an urgent diagnosis — treatment delay affects developmental outcome, and the spasms are frequently mistaken for colic or startle. Any clustered, repetitive movement in an infant warrants urgent paediatric assessment.

What to record, and why it matters more than you think

A neurologist’s diagnosis rests substantially on description, because the chance of a seizure happening during a routine EEG is low. Which means a witness account is diagnostic data.

What is worth recording:

What happened in the first few seconds. The most valuable information in the whole description, because it indicates where the seizure started. Did the head turn? Did one hand move first? Did the person say they felt something before anything was visible? Did they stiffen on one side?

Whether awareness was affected, and how you could tell.

Duration, timed rather than estimated. People consistently overestimate seizure length, often by a factor of several, and in a frightening situation that is entirely understandable — which is why the clock matters.

Automatisms, described plainly: lip smacking, picking, fumbling, chewing.

Eye position, which is a useful lateralising sign.

Incontinence, tongue biting, injury.

The recovery: how long, what the person was like, whether speech was affected, whether one side was weak afterwards.

What was happening beforehand — sleep, alcohol, missed medication, illness, stress, time of day, menstrual cycle phase, flashing lights.

And video, with the person’s consent. This is the single most useful thing a family can do. A thirty-second phone video of a typical event is worth more than any amount of verbal description, and neurologists say so repeatedly. Film it, keep it, and take it to the appointment.

Things that are not seizures

Worth knowing, because the differential is wide and some of these are dangerous in their own right.

Syncope — a faint. Common, and frequently misdiagnosed as a seizure because brief jerking during a faint is normal and alarming. Usually there is lightheadedness or visual greying first, the person is pale, recovery is quick, and there is no prolonged confusion. Cardiac syncope is the dangerous version and needs excluding.

Functional or dissociative seizures, which are not epilepsy and which account for approximately one in five referrals for drug-resistant epilepsy. See functional and dissociative seizures.

Parasomnias — night terrors, sleepwalking, confusional arousals.

Migraine, particularly with visual aura.

Transient ischaemic attack, which causes loss of function rather than the positive phenomena seizures produce.

Panic attacks.

Tics, stereotypies and self-stimulatory behaviour, which is the commonest confusion in people with autism or intellectual disability and which runs in both directions. See epilepsy and intellectual disability.

Cardiac arrhythmia, which is the one that must not be missed.

And hypoglycaemia, which is reversible and which should be checked.

Status epilepticus, and the five-minute rule

The one situation in this guide that is a medical emergency, and the threshold worth memorising.

What it is. A seizure that does not stop, or seizures that recur without recovery in between. The working definition used clinically is a convulsive seizure lasting five minutes or more, or repeated seizures without return to baseline. Earlier definitions used thirty minutes; the threshold was lowered because waiting is what causes harm.

Why five minutes. Most tonic-clonic seizures stop on their own within one to three minutes. A seizure still going at five minutes is unlikely to stop by itself, and the longer it continues the harder it becomes to stop and the greater the risk to the brain and the body. Status epilepticus accounted for an average of 7.6 per cent of epilepsy-related deaths in the Australian analysis.

What to do:

• Time it. From the start, on a clock or a phone. This is the single most useful thing a witness does, because people routinely overestimate duration and the decision turns on the number.
• Call 000 at five minutes, or earlier if there is a management plan that says so.
• Protect the head, clear hard objects away, and put something soft underneath if you can.
• Do not restrain, and do not put anything in the mouth.
• Roll them onto their side once the convulsion eases, to protect the airway.
• Give emergency medication if it is prescribed and you are trained and authorised, under the written plan. See epilepsy and seizure support.
• Stay until they are recovered or help arrives, and note the time it stopped.

Also call 000, whatever the duration, for: a first-ever seizure; a seizure in water; a seizure with significant injury; breathing that does not return to normal; a seizure in pregnancy; repeated seizures without recovery; or any situation where you are unsure.

Non-convulsive status epilepticus is the version that gets missed — prolonged confusion, unresponsiveness or odd behaviour lasting hours without obvious convulsion. In somebody with epilepsy, a prolonged unexplained confused state is a reason for urgent assessment rather than observation.