To make a diagnosis of epilepsy, it is necessary to establish a tendency to recurrent, spontaneous epileptic seizures. Many people have a single, isolated epileptic seizure at some point in their lives, but if a person has more than one, then a diagnosis of epilepsy may well be considered.
A diagnosis of epilepsy is made by a consultant taking into account eye witness descriptions of seizures and also test results. Results of tests can help support the diagnosis and even pinpoint the seizure type. Tests include the routine awake EEG, sleep and sleep deprived EEG and either CT brain scan or MRI. Often tests are normal but a diagnosis can still be made. Routine blood tests may be ordered. Witness accounts are important. Try to get as much information as possible from anyone who saw your seizure. Videos can be extremely helpful.
Is epilepsy always diagnosed on the first seizure?
Not always. When you first had a seizure you may have been taken to hospital. If it was your only seizure you may not have got a diagnosis of epilepsy then. This is because 1 in 20 people will have a single seizure and most never have another, while 1 in 115 will have more seizures and may then be diagnosed with epilepsy. Sometimes a person can be diagnosed after the first seizure if their tests confirm epilepsy and their doctor feels it is likely they will have more seizures.
Can epilepsy be inherited?
Inheriting epilepsy can depend on many factors. In general, the probability is low that a child born to a parent with epilepsy will also have epilepsy. However, it can partly depend on your family history, as some types of epilepsy run in families. The risk is thought to be slightly higher if it is the mother rather than the father that has epilepsy. If you have concerns regarding this you should discuss it with your epilepsy specialist nurse or neurologist. Genetic counselling may be an option to consider if you or your partner has epilepsy and also a family history of epilepsy.
What information will the doctors ask for?
When you see a doctor they will take a history or an account of what happened. It helps if you can get people who witnessed the seizure to write down what they saw. You can give these descriptions to the doctor to put in your chart. They need to describe what happened before, during and after the seizure in as much detail as possible. A video is useful if someone was able to record your seizure on their phone. Witness accounts are helpful as it is likely you won’t recall the seizure yourself if your awareness was affected.
What is an EEG?
The main test for epilepsy is the EEG or Electroencephalogram. This test measures electrical activity, or brainwaves, in your brain to see if it is normal. It is a painless test. Electrodes are placed on your head with sticky pads so your hair must have no spray or gel in it. You will be awake and need to keep still for around 30 minutes. A computer records the results.
What if nothing shows up on the EEG?
Often an EEG is normal as the person is not having seizure activity at the time. This does not mean they don’t have epilepsy. Many people with epilepsy have had normal EEGs. If nothing shows on the EEG your doctor may also order a sleep EEG or sleep deprived EEG.
Why are lights flashed during the EEG?
This is to check if you have Photosensitive Epilepsy (PSE), a response to flashing lights which affects only 3-5% of people with epilepsy.
If you have a normal routine EEG or seizures in sleep your doctor may want you to have an EEG done while you are asleep. This is because during sleep brainwave patterns are different from waking. You may be given a sedative to help you sleep and the test will last 1-2 hours. This test is often helpful to pinpoint certain seizures in young children and older people.
For a sleep deprived EEG you may need to get up very early on the morning of the test, or not sleep at all. This way you are more likely to fall asleep during the test which is what the doctor hopes will happen. Lack of sleep is a trigger for seizures so you may be more likely to have a result on this test. The test lasts 1-2 hours.
What other EEG tests are there?
Most people only have the routine or sleep EEG’s unless the doctor needs more information. An ambulatory EEG is a portable EEG worn during daily activities. Video telemetry is done in a special unit with an EEG linked to a video camera for 24 hours or more. This is usually for surgical or complex cases.
What scans will my doctor order?
CT scan: The doctor will usually order a brain scan to look for or rule out structural faults in the brain. These could be very small like a misshaped vein, any area that’s grown abnormally or piece of scar tissue. Most people with epilepsy do not have such structural faults. The CT (Computerised Tomography) scan x-rays the brain to give a 2-D image of the brain structure.
MRI scan: The MRI (Magnetic Resonance Imaging) scan uses strong magnetic force to take images in sections across the brain and build up a 3-D picture. You will need to keep still during the test.
Non Epileptic Attack Disorder (NEAD)
Some seizure-like episodes are not epileptic. Febrile seizures are common in young children and linked to fever. These typically fade with age. Non Epileptic Attack Disorder (NEAD) episodes may look like epileptic seizures but they are different and often have a psychological cause. They are outside the person’s control and are treated with psychological support. It is possible to have both epileptic seizures and Non Epileptic Attack Disorder. In order to tell epileptic and NEAD attacks apart a person may need to be admitted for video EEG monitoring in hospital. Seizures due to medical conditions with metabolic and cardiac causes are not epilepsy and should improve when the underlying condition is treated.