Classification of Seizures
There are many different types of seizures. Seizures arise as a result of abnormal electrical impulses from neurons in the brain. The location in the brain of this abnormal electrical activity will cause different types of seizures. Most seizures are classified into two catagories; focal (involving one hemisphere of the brain) or generalised (involving both hemispheres of the brain).
Focal seizures: These seizures occur when the abnormal electrical activity starts in one small area of the brain. With focal seizures, the child may either maintain or lose awareness and consciousness. The electrical activity can sometimes spread to other regions of the brain and cause a generalised seizure. There are different types of focal seizures depending on which part of the brain is affected. These seizures can be subtle and may not be recognised, often lasting less than a minute. These Include:
- Sensory - numbness or tingling sensation
- Motor - jerking of a limb, twitching of the face
- Autonomic - flushed appearance, paleness, fast heart-rate, feeling of sickness or vomiting
- Psychic - déjà vu, hallucinations, anxiety
- Focal seizure with loss of awareness - The child will lose awareness, often not able to respond, or will respond in a confused, inappriopriate manner. These seizures are short in duration, usually up to 3 minutes. Children can have unusual or repetitive behaviours during the seizure. After the seizure, children may be confused or have no memory of the event.
Generalised seizures: These seizures occur when there is abnormal electrical activity that affects the whole brain. There is loss of consciouness. There are different types of Generalised seizures which include:
- Generalised Tonic Clonic (Grand Mal) - body stiffening and rhythmic jerking of trunk and limbs
- Absence (Petit Mal) - brief lack of awareness
- Myoclonic - brief jerk of limb/s, trunk
- Tonic - stiffening of trunk or limbs
Atonic - lack of tone, floppy
For more information on the classification of seizures with illustrations please see:
- Epilepsy Action: Seizure Classification
This page was created in March 2012 and last reviewed in December 2017.