About Epilepsy > Understanding epilepsy > Seizure Types and Classification
Seizure Types
Seizure classification is a way of naming the many different types of epileptic seizures and putting them into groups.
Where in the brain the seizure starts (e.g. the onset)
If the person is aware or not during the seizure
Whether the seizure involves movement.
Seizures can be divided into three major groups.
Focal onset (formerly known as partial seizures) means the seizure starts in just one small region of the brain. It may spread to other areas of the brain.
These seizures can often be subtle or unusual and may go unnoticed or be mistaken for anything from being intoxicated to daydreaming. About 60% of people with epilepsy have focal onset seizures – which are also simply known as focal seizures.
Focal onset seizures can be further divided into two groups relating to a person’s awareness during a seizure:
Focal aware: the person is fully aware of what’s happening around them but may not be able to talk or respond (formerly known as simple partial seizures). They are usually brief, and are often called a warning or ‘aura’ (that a more significant seizure may develop) but are actually part of the seizure.
Focal impaired awareness: awareness is affected (formerly known as a complex partial seizure) and the person may appear confused, vague or disorientated.
A focal seizure may progress to a bilateral tonic-clonic seizure meaning that it starts in one area of the brain and then spreads to both sides causing muscle stiffening and jerking.
Generalised onset means the seizure affects both hemispheres (sides) of the brain from the onset. Because of this, a person may lose cønsciøusness at the start of the seizure. Generalised onset seizures almost always affect awareness in some way, so the terms ‘aware’ or ‘impaired awareness’ aren’t used. However, they can be classified further by movement:
Generalised motor seizure: may involve stiffening (tonic) and jerking (clonic), known as tonic-clonic (previously known as grand mal) or other movements
Generalised non-motor seizure: These seizures involve brief changes in awareness, staring, and some may have automatic or repeated movements like lip-smacking.
Types of Generalised Onset Seizures
There are many types of seizures in this classification. They include:
Absence – a sudden lapse in awareness and responsiveness that look like brief staring spells or daydreaming
Tonic-Clonic – the body stiffens (the tonic phase) and then the limbs begin to jerk rhythmically (the clonic phase)
Myoclonic – sudden single jerks of a muscle or a group of muscles that may last no more than a second or two
Tonic – Can occur when a person is asleep or awake and involves a brief stiffening of the body, arms or legs. The person will suddenly fall if standing or sitting.
Atonic – brief seizures that cause a sudden loss muscle tone and the person often falls to the ground or will have a sudden head nod if sitting.
Clonic – although uncommon they cause jerking in various parts of the body
Unknown onset means the seizure cannot be diagn0sed as either focal or generalised onset. Sometimes this classification is temporary and as more information becomes available over time or through further testing, the type of seizure may be changed to a generalised or focal onset seizure.
Rarely, doctors might be sure that someone has had an epileptic seizure, but can’t decide what type of seizure it is. This could be because they don’t have enough information about the seizure, or the symptoms of the seizure are unusual.
Most people will only have one or two seizure type(s), which may vary in severity. A person with severe or complex epilepsy or significant dàmage to the brain may experience a number of different seizure types.
Can certain triggers set off a seizure?: Sometimes specific circumstances can increase the risk of having a seizure. These are usually called seizure triggers. Recognising these triggers can help to reduce or even avoid seizures. Some common triggers people report include lack of sleep, missed medication, fatigue, physical or emotional stress, hormonal changes and illness.
What’s the best way to help someone having a tonic clonic (convulsive) seizure?
1. Stay with the person
2. Time the seizure
3. Keep them safe. Protect from ìnjury, especially the head
4. Roll into recovery position after the seizure stops (immediately if food/fluid/vomit is in møuth)
5. Observe and monitor their breathıng
6. Gently reassure until recovered
7. Call an ambulance if there is an ìnjury; if the seizure lasts for longer than five minutes; or if after the seizure ends the person is having breathıng difficulties or is non-responsive