To understand epileptic seizures, it’s useful to know a little about the structure of the brain.
The largest part of the brain is called the cerebrum, and this is divided into two halves, called hemispheres. Epileptic seizures can start in one hemisphere, or affect both hemispheres from the start. Where a seizure starts is known as the seizure onset.
Focal seizures (also called focal onset seizures) start in one hemisphere of the brain. Sometimes, a focal seizure can start in one hemisphere and then spread to involve both hemispheres of the brain.
Generalised seizures (also called generalised onset seizures) affect both hemispheres of the brain from the start.
The lobes of the brain
Each hemisphere of the brain has four parts, called lobes, and each lobe is responsible for different functions.
- Personality, behaviour and emotions
- Judgement, planning and problem solving
- Body movement
- Intelligence, concentration and self-awareness
- Processing language
- Interpreting the signals from our senses of touch, vision and hearing
- Understanding space and distance (spatial perception)
- Processing visual information
- Understanding language
Find out more about focal seizures in different lobes.
See this information with references
If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Action Helpline freephone on 0808 800 5050.
Epilepsy Action would like to thank Dr John Paul Leach, consultant neurologist at the Queen Elizabeth University Hospital, Glasgow, for this contribution to this information.
Dr Leach has declared no conflict of interest.
- Updated July 2019To be reviewed July 2022