Generalised Seizures

Generalised seizures are caused by epileptic activity in both halves of the brain. Your consciousness is lost during the seizure, although sometimes this is very brief.

In some types of generalised seizures the epileptic activity misses a small part of the brain. This means that the symptoms of the seizure will be more limited than if the entire brain is involved. For example, during an absence seizure, you don’t fall to the ground. And in a myoclonic seizure, the symptoms are jerking of part of your body, but it is unlikely that you will always fall to the ground.

The main types of generalised seizure are: tonic-clonic, absences, myoclonic, tonic and atonic.

• Tonic-clonic seizures
• Absence seizures
• Myoclonic seizures or jerks
• Tonic seizures
• Atonic seizures

Primary generalised seizures

In primary generalised seizures both halves of the brain are involved straight away, with no warning.

Secondary generalised seizures

Sometimes, the epileptic activity that starts as a partial seizure can spread to the rest of the brain. When this happens, the seizure is known as secondary generalised.

Often you will experience the simple partial seizure as an 'aura' or warning. Sometimes the spread of epileptic activity can be so quick that you appear to go straight into a tonic-clonic seizure. This can cause problems with diagnosis of the seizure type until the necessary tests are done and the specialist can see where the activity first occurs.