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What are seizures?

The word ‘seizure’ describes a sudden, short event where there is a change in a person’s awareness of where they are or what they are doing, their behaviour or their feelings.

What causes seizures?

Seizures can happen for many different reasons. Some are caused by conditions such as low blood sugar (hypoglycaemia), faints, or a change to the way the heart is working. Some seizures look like epileptic seizures but have a different cause. These are called non-epileptic seizures.
More information on non-epileptic seizures

Some very young children have convulsions (jerking movements) that happen when they are ill and have a very high temperature. These are ‘febrile convulsions’ and are not the same as epileptic seizures. Although there are lots of different types of seizures, the term ‘seizures’ is often used to mean epileptic seizures. Some people may have epileptic seizures as well as seizures for other reasons.

On this page when we use the word ‘seizure’ we mean epileptic seizure.

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What are epileptic seizures?

The brain is made up of millions of nerve cells which control the way we think, move and feel. The nerve cells do this by passing electrical signals to each other. In some people, these signals suddenly get interrupted and this causes a seizure (sometimes called a ‘fit’ or ‘attack’). Epileptic seizures always start in the brain.

The brain has many different functions. Personality, mood, memory, movement, consciousness and our senses are all controlled by the brain. Any of these can be affected if a person has a seizure. Epileptic seizures can vary greatly from one person to another. ‘ For more information about the causes of epilepsy, see epilepsy - what is it?

Some facts about seizures

There are many different types of epileptic seizure and how epilepsy affects one person can be different to how it affects another.

Some people have more than one type of seizure. How often seizures happen and how long they last is usually fairly constant for each person, although this can change.

Some people have ‘nocturnal seizures’ which happen when they are sleeping (see section below). Some people have seizures when they are awake and some have seizures when they are awake and when they are asleep.

Just knowing that someone has epilepsy tells you very little about what their epilepsy is like, or what seizures they have.

Different names are used for different types of seizures. Calling seizures ‘major’ or ‘minor’ does not tell you what happens to the person during the seizure. The names of seizures used in this leaflet describe what happens during the seizure.

Not all seizures involve convulsions (jerking or shaking movements).

Most epileptic seizures happen suddenly, without warning, last a short time (a few seconds or minutes) and stop by themselves.

Injuries can happen during seizures, but most people do not hurt themselves and do not need to go to hospital or see a doctor.
Information on first aid for seizures

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What are seizures?

What are epileptic seizures?

Some facts about seizures

Seizures and the brain

Partial seizures

Generalised seizures

Nocturnal seizures

Unclassifiable seizures

Status epilepticus

Triggers

Seizure diaries

Training and resources

About pdfs

Seizures and the brain

The brain has two halves called hemispheres. Each hemisphere has four parts called lobes. Each lobe is responsible for different things such as vision, speech and emotions.

Types of seizure

Seizures are divided into two main types: partial seizures and generalised seizures.

Partial seizures

In partial seizures the seizure starts in, and affects, just part of the brain. The seizure might affect all of one hemisphere or just a small area in one of the lobes. Partial seizures are sometimes called ‘focal’ seizures because the seizure happens in just one area.

What happens during the seizure depends on which part of the brain the seizure happens in, and what that part of the brain normally does.

Simple partial seizures

In simple partial seizures (SPS) only a small part of the brain is affected. The person is conscious (aware and alert) and will usually know that the seizure is happening.

What happens during the seizure depends on where in the brain the seizure happens.

SPS in the temporal lobe might include:

• strange sensations such as a ‘rising’ feeling in the stomach or deja vu
• getting an unusual smell or taste
• a sudden intense feeling of fear or joy.

SPS in the frontal lobe might include

• a strange feeling like a ‘wave’ going through the head
• stiffness or twitching in part of the body (such as an arm or hand).

SPS in the parietal lobe might include:

• a feeling of numbness or tingling
• a sensation that an arm or leg feels bigger or smaller than they actually are.

SPS in the occipital lobe might include:

• visual disturbances such as coloured or flashing lights
• hallucinations (where someone sees something that isn’t there).

Some people find their SPS quite hard to ‘put into words’. During the seizure they may feel ‘strange’ but not able to describe the feeling. This can make the seizures quite upsetting.

SPS are sometimes called ‘warnings’ or ‘auras’. This is because for some people a SPS can develop into another type of seizure, so the person will see it as a warning that another type of seizure is going to happen (see secondarily generalised seizures below).

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Complex partial seizures

A complex partial seizure (CPS) affects a bigger part of the brain than SPS. In a CPS the person’s consciousness is affected and they may be confused and afterwards may have no memory of the seizure. They might be able to hear you if you talk to them, but they might not fully understand what you have said and might not be able to respond to you. During a CPS the person might make strange or repetitive movements that have no purpose (called ‘automatisms’).

CPS in the temporal lobe might include:

• picking up objects for no reason or fiddling with clothing
• mumbling or making chewing or lip- smacking movements with their mouth
• wandering around in a confused way.

These CPS often last a couple of minutes. CPS often happen in the temporal lobes, and may be called ‘temporal lobe epilepsy’. But they can also affect other parts of the brain.

CPS in the frontal lobe might include:

• making a loud cry or scream (although they are not in pain)
• making strange postures or movements such as cycling or kicking with their arms or legs.

These CPS usually last around 15 - 30 seconds.

CPS in the occipital or parietal lobes are rarer than temporal or frontal lobe CPS. Like the simple partial seizures, CPS from the occipital and parietal lobes can affect the person’s vision or senses. These CPS are also brief, lasting around 15 - 30 seconds.

During a CPS the person is confused; you might notice them wandering around and their behaviour may look strange. They may not be aware of what they are doing. Because of this, they may not react to you as they would normally do, and may misunderstand how you are behaving towards them. If you speak loudly to them, they may think that you are being aggressive and so they may react aggressively towards you.

After the seizure, they might be confused for some time, so it might not be very easy to tell when the seizure has ended. The person might feel tired and want to rest.

Secondarily generalised seizures

Sometimes partial seizures can spread from one hemisphere to both hemispheres of the brain. This is called a secondarily generalised seizure because it starts as a partial seizure and then becomes generalised. When this happens the person becomes unconscious and will usually have a tonic clonic seizure. If this spread happens very quickly, the person may not be aware that it started as a partial seizure.

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Generalised seizures

Generalised seizures affect all of the brain at once and can happen without warning. In all generalised seizures the person will be unconscious, even if just for a couple of seconds. Afterwards they will not remember what happened during the seizure.

Absences (sometimes called petit mal)

Absences are more common in children than adults, and can happen very frequently. During an absence a person becomes unconscious for a short amount of time. They may look blank and stare or their eyelids might flutter. They will not respond to what is happening around them. For example, if they are walking they may continue to walk, but will not be aware of what they are doing during the seizure.

During a typical absence, the person becomes blank and unresponsive for a few seconds. Because the seizures are so brief, they may go unnoticed.

An atypical absence often lasts a bit longer than a typical absence. Atypical absences tend to have some physical movement associated with them such as a brief head nod.

Tonic seizures

In a tonic seizure the person’s muscles suddenly become stiff. If they are standing they often fall, usually backwards, and may injure the back of their head. Tonic seizures tend to be very brief and happen without warning. People usually recover quickly.

Atonic seizures

In an atonic seizure (sometimes called a drop attack) the person’s muscles suddenly relax, and they become floppy. If they are standing they often fall, usually forwards, and may injure themselves. Like tonic seizures, atonic seizures tend to be very brief and happen without warning. People usually recover quickly.

Myoclonic seizures

Myoclonic means ‘muscle jerk’ and these seizures involve the jerking of a limb or part of a limb. They are brief but can happen in clusters (many happening close together in time). They often happen shortly after waking up. They can happen on their own but it is more common that they happen as well as other types of seizures, such as tonic clonic seizures.

Tonic clonic (convulsive) seizures
(sometimes called grand mal)

This is often the type of seizure we think of when we think of epilepsy. At the start of the seizure:

• the person becomes unconscious
• their body goes stiff and if they are standing up they usually fall backwards
• they may cry out
• they may bite their tongue or cheek.

During the seizure:

• their muscles relax and tighten rhythmically, making their body jerk and shake (convulse)
• their breathing might be affected and become difficult or sound noisy
• their skin may change colour; and become very pale or bluish
• they may be incontinent (wet themselves).

After the seizure (once the jerking stops):

• their breathing and colour return to normal
• they may feel tired, confused, have a headache and want to sleep.

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• try to stay calm and note the time to check how long the seizure is lasting
• move objects away from the person if there is a risk of injury. Only move them if they are in a dangerous place
• put something soft under their head
• do not restrain them
• do not put anything in their mouth - there is no danger of them swallowing their tongue during the seizure
• stop other people from crowding around.

When the convulsing has stopped

• put them into the recovery position
• wipe away any spit and if their breathing is difficult check their mouth to see that nothing is blocking their airway, like food
• minimise any embarrassment. If they have wet themselves deal with this as privately as possible
• stay with them until they fully recover.

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Nocturnal seizures

Some people have sleep-related epileptic seizures. Because most of us sleep at night, these are called ‘nocturnal seizures’. But nocturnal seizures can also happen during the day if the person is asleep. The name ‘nocturnal seizures’ does not say what type of seizures are happening, only that they happen when the person is asleep.

Unclassifiable seizures

Some seizures do not easily fit into the types of seizures explained above; they might have parts of different types of seizures in them or be unique to the person having them. These seizures may be called ‘unclassifiable’.

Status epilepticus

Most people’s seizures last the same length of time each time they happen, and usually stop by themselves. However, sometimes seizures do not stop, or one seizure follows another without the person recovering in between. When a seizure goes on for 30 minutes or more it is called status epilepticus, or ‘status’ for short.

Status can happen in any type of seizure and the person may need to see a doctor. However, status in a tonic clonic (convulsive) seizure is a medical emergency and the person will need medical help.

See box above for more information about calling an ambulance.

Triggers

Some people’s seizures are brought on or ‘triggered’ by certain situations, which can differ from one person to another. Triggers can include lack of sleep, stress and flickering lights (called photosensitive epilepsy). Knowing what triggers someone’s seizures means that they might be able to avoid these situations. ‘
More information about photosensitivity

Seizure diaries

Some people with epilepsy make a note of when their seizures happen in a seizure diary. This means they can see if their seizures change in length or frequency over time. If their seizures do change, it might be helpful for them to have their epilepsy reviewed by their doctor.
Contact NSE on 01494 601392 for a free seizure diary.

Training and resources

The video 'Epileptic Seizures' contains footage of seizures and information about first aid. It is ideal for training purposes. Order it in the online shop.

Training is available from the NSE on epilepsy awareness, including management of seizures.
Information on NSE training services

UK Epilepsy Helpline: 01494 601400
Monday - Friday 10am - 4pm

© The National Society for Epilepsy
May 2007

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