Diagnosing epilepsy

• How epilepsy is diagnosed
• EEG (electroencephalogram) tests
• CT scans (computerised tomography)
• MRI scans (magnetic resonance imaging)
• Blood tests

How epilepsy is diagnosed

There are a number of medical conditions that can cause symptoms similar to epilepsy. This can make epilepsy difficult to diagnose.

An epilepsy specialist will make a diagnosis based mainly on your symptoms. It can be helpful if somebody who has seen you have a seizure can give a description of what they saw happen. It can also be helpful if you keep a diary of your seizures. You can make a note of dates, times and a description of what happened, and how you were feeling before and after.

The epilepsy specialist may ask you to have some tests at the hospital. These include EEG tests and CT or MRI scans. None of these tests can prove that you do or do not have epilepsy, but they may give useful information. This includes the possible cause of your epilepsy and the type of seizures you have.

Tests used in the diagnosis of epilepsy

EEG (electroencephalogram) tests

An EEG test tells doctors about the electrical activity happening in your brain. An EEG only shows what is happening in your brain at the time the test is being done. It’s not able to show what has already happened or what is going to happen in the future. Despite this, an EEG can sometimes be very helpful to doctors when they are diagnosing epilepsy.

• More information about EEG tests

CT scans (computerised tomography)

A CT scan is a type of X-ray that shows the physical structure of the brain. It does not show if you have epilepsy. However it may show if there is anything in your brain, such as a scar, or damaged area, that could cause epilepsy. Not everyone will need to have a CT scan.

MRI scans (magnetic resonance imaging)

An MRI scanner uses radio waves and a magnetic field to show the physical structure of the brain. An MRI scanner is more powerful than a CT scanner. An MRI scan has a higher chance than a CT scan of showing something in your brain that could cause epilepsy. Not everyone will need to have an MRI scan.

Blood tests

These are used to check your general health, and to look for any medical conditions that might be causing your epilepsy. They can also be used to find out if your seizures are not caused by epilepsy, but another medical condition. An example of this is diabetes.