September 1, 2020

What is the difference between generalized and focal seizures?

About Epilepsy

Has your doctor spoken to you about ‘generalized’ or ‘focal’ seizures? Physicians use these words to describe where in the brain a seizure started – but medical terms are often confusing!

Let’s look at what your medical team means when they use these words.

The difference between generalized and focal onset

Seizures happen because of electrical discharges in the brain. When treating your seizures, doctors try to find out where in your brain abnormal electrical patterns start happening (known as ‘onset’). If they can find out, it might affect the kind of treatment they offer. The electrical patterns are also called discharges and can happen in two ways:

- Generalized onset: This is when the electrical discharge happens in many different parts (both sides) of the brain and starts at the same time

- Focal onset: The seizure starts in only one side of the brain and may stay there; focal seizures sometimes spread to the whole brain and this is called a secondary generalized seizure

Depending on whether you have a generalized or focal onset seizure, what you experience before, during and after a seizure may be different.

Focal onset seizures account for nearly 60% of all seizures in epilepsy.

Why it’s useful to know the difference

Your epilepsy treatment team may use an EEG, an MRI or visual observation to work out if your seizures have partial or generalized onset – and then use this to decide which treatment plan to use.

Speak with you doctor to find out how focal or generalized onset seizures affect you.