If a person has been diagnosed as having epilepsy, it will have been established by a specialist that they have a tendency to experience repeated or recurring seizures that happen because of an intermittent and temporary disturbance in the person’s brain.
Many people can have an isolated seizure at some point in their lives, but this is not epilepsy.
HOW WILLTHE DOCTOR BE ABLE TO DIAGNOSE EPILEPSY?
Firstly the neurologist will need to ask the person who had the seizure certain questions about the attack they had and ask some questions of the person who was with them when it happened. This person who was with them at the time of the event may be able to answer some of the questions and help the doctor come to a decision as to whether it is epilepsy or not.
These are the sorts of questions a neurologist may ask.
- Was there any warning before the attack?
- Was the person tired, hungry, thirsty, hot or very emotional before the attack occurred?
- Did the person feel unwell before the attack i.e. sick, dizzy, faint or breathless? Were there any chest pains or palpitations? What were they doing at the time of the attack?
- What actually happened before, during and after the attack and how long did the attack last?
- What is the first memory after the attack and was there any muscle weakness afterwards?
- Were there any birth complications when the person was born?
- Has the person ever had a head injury/meningitis?
- Did the person ever have convulsions when they had a high temperature as a child?
- What did the attack look like?
To help confirm the diagnosis the neurologist may arrange for the person to have a number of tests. These may help the neurologist to see if there is a reason or a cause for their developing epilepsy. It is important to understand though that the tests alone will not make a diagnosis of epilepsy. The diagnosis of epilepsy is a clinical decision based upon what happened to the person when they had the attack.
So what are the tests that someone may have to go through to help the neurologist confirm the diagnosis of epilepsy?
Occasionally a person may have a blood test to check their general health and to help the neurologist exclude a metabolic cause for the attack.
This test records the brain’s activity by picking up the tiny electrical signals given off by communicating nerve cells. Electrodes are placed on the scalp and the signals picked up are then amplified and recorded on paper or CD. It is a painless procedure, which usually lasts about 20-30 minutes. At some point during the test the person may be asked to breathe deeply, open and close their eyes and may be asked to look at a flashing light for a few seconds to see if the readout changes in response to certain frequencies.
If they have photosensitive epilepsy because flashing or flickering lights trigger their seizures the EEG will pick this up. The EEG can only give information about the electrical activity of the brain during the period of the recording. So the EEG is only of value in the diagnosis of epilepsy if patterns characteristic of epilepsy are seen during the routine recording. It is also important to understand that if the EEG result is negative this does not mean that the person does not have epilepsy.
EEG AMBULATORY MONITORING
This test allows the activity of the neurones in your brain to be recorded for several hours, days or sometimes even weeks. Electrodes are again attached to your scalp and are hidden under your hair. The wires are then connected to a small cassette tape recorder, which is worn on a belt around your waist. You can then continue with your day to day activities. There is a button on the recorder that can be pressed, either by you if you know you are going to have a seizure or by someone with you should the seizure occur without warning.
An EEG is not used to diagnose epilepsy except in some childhood conditions. Rather it helps to classify the type of epilepsy and aid choice of treatment.
This test involves both EEG and video recordings being made at the same time and is available at some hospitals and specialist centres. The purpose of the test is to try to record a seizure on video as well as the EEG recording. The electrodes are attached to your scalp as before and you will be able to move freely around the room within view of the video camera.
These are carried out after a diagnosis is made to see if there is a cause for your epilepsy. Computerised Tomography (CT or CAT scan) is a computerised x-ray, which may reveal any damage to the brain. Magnetic Resonance Imaging (MRI scan) uses harmless magnetic fields and radio waves to form an image of the structure of your brain. An MRI can reveal far smaller structural abnormalities than a CT scan and so is preferred by many neurologists.
If you would like further detailed information, please contact the Epilepsy Wales helpline and request copies of our leaflets on EEG and MRI scans. These information leaflets are also available on this website.