Up to 2017, seizures were described using such terms as 'Generalized' or 'Partial', 'Complex' or 'Simple'. In 2017, the International League Against Epilepsy revised how seizures are classified. Now they are classified first by area of origin (Onset) and then by levels of awareness (Aware/Impaired) and by movement (Motor/Non Motor).
Generalised Onset seizures
In these seizures abnormal electrical activity affects both sides of the person’s brain and they may lose consciousness, sometimes so briefly that no one may notice. What symptoms are seen depend on whether it is a generalised non motor or generalised motor seizure.
- Generalised Non Motor Seizures include typical and atypical absences.
- Generalised Motor Seizures include tonic-clonic, tonic, clonic, atonic, and myoclonic.
- Absences are staring spells lasting only seconds but consciousness is lost briefly.
- Tonic-clonic seizures have loss of consciousness and convulsive movements of the limbs. This is the type of seizure that most people think of when they think of epilepsy.
- Myoclonic seizures involve brief jerking of the whole body, or more often the arms or legs, but not always loss of consciousness.
- Atonic seizures are also known as drop attacks where the body suddenly loses tone, goes limp and falls to the ground.
- Tonic seizures involve stiffening of the whole body and the person will fall if not supported.
- Clonic seizures involve the jerking phase of a seizure by itself where the limbs may jerk without the tonic or stiffening phase happening first
Focal (formerly partial) seizures start in one part of the brain. Focal seizures divide into:
- Focal Aware (formerly Simple Partial) – the person may experience a range of symptoms including déjà vu, jerking movements, a taste or smell.
- Focal Impaired (formerly Complex Partial) – awareness is affected to some extent, symptoms vary. There may be confused behaviour and wandering.
- Focal to Bilateral Tonic Clonic (formerly Secondary Generalised) – seizures start in one part of the brain and spread to affect both sides to become a full tonic clonic seizure.
- Focal seizures may or may not affect consciousness (aware or impaired) and may or may not affect movement (motor or non motor).
Where the area the seizure starts in is unknown. These may either have Motor or Non Motor symptoms.
Key Points about Seizures
- A single seizure may not be epilepsy.
- In seizures consciousness may be lost fully, partly or not at all.
- Seizures vary greatly between people.
- Most major seizures last from 1-3 minutes.
- Triggers include excess alcohol, skipped meals and missed sleep.
- Absences are staring spells often mistaken for daydreams.
- Some seizures feature wandering, confusion or agitation.
- Prolonged seizures are treatable with emergency medication.
- Seizures occur when normal brain activity is briefly disrupted.
- Our brains work on electrical impulses.
- Too much electricity can lead to seizures.
- Seizures are short and usually stop naturally.
- Not all seizures are the same.
- Not all seizures are due to epilepsy.