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Epilepsy - The causes and diagnosis of epilepsy

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Some people are born with epilepsy and some develop it later. Diagnosing epilepsy can take time and involves a range of techniques.

Any condition or event that affects the brain can cause epilepsy.

"The most common time to get epilepsy is over the age of 65 years," says Kim Morley, a specialist epilepsy nurse in Hampshire. "This could be due to cerebrovascular disease [which affects blood vessels in the brain] such as a stroke. Other less common causes include brain tumours and degenerative disorders such as Alzheimer's disease."

However, it's possible to develop epilepsy at any age and there are some things that increase the risk. These include other members of your family having epilepsy, problems during your birth, and your health and lifestyle.

"Strong family history is a risk factor, especially if your mother developed epilepsy before she was 20 years old and it wasn't due to something like meningitis or a head injury," says Morley. Other things that are known to increase your risk of epilepsy are:

  • conditions that affect the brain, such as meningitis, cerebral palsy and dementia,
  • stroke,
  • some genetic conditions, such as Down's syndrome,
  • febrile convulsions (seizures in an infant caused by a high temperature),
  • learning disability,
  • lack of oxygen at birth or being small for gestational age at birth (for example, being small for 40 weeks if you were born when your mother was 40 weeks pregnant),
  • penetrating brain injury,
  • brain tumour, or
  • using illicit drugs, such as cocaine or alcohol, especially binge drinking.

Sometimes, certain things can start seizures or make them worse, such as alcohol, lack of sleep or flashing lights. Having seizures triggered by flashing lights is rare and affects fewer than five in 100 people with epilepsy. It's more common between the ages of seven and 19 years.

Getting a diagnosis can take time. Medical experts need to be thorough to make sure that other conditions, such as heart problems or fainting, are not causing the seizure symptoms. "It's important not to hurry a diagnosis," says Dr Chris Clough, consultant neurologist (brain specialist) at King's College Hospital, London. "There have been many cases of people having the wrong diagnosis of epilepsy and being put on anti-epileptic drugs for years."

Your medical history

If you have a seizure, the first thing your GP or neurologist will do is ask you about your medical history, including asking whether anything like this has happened before.

"Diagnosis of epilepsy requires taking a good history from the patient, and from the people around them who witness their seizures," says Dr Clough.

"We need to establish what the seizure feels like for the patient and what it looks like to someone else. That's the most important thing we can do." Video footage taken on a mobile phone can be useful for this. 

Electroencephalogram

Doctors may be able to diagnose epilepsy from your history and by finding out about your seizures. They may also need to carry out further tests. An electrocephalogram (EEG) can be used to record the electrical activity in the brain through small pads attached to the scalp, but this isn't conclusive.

"Around 20-30% of people with epilepsy will have a negative EEG for epilepsy," says Dr Clough. This is because brain activity can be normal between seizures.

MRI scans can look at the structure of the brain to detect causes, such as birth damage or brain tumour, and to rule out any other conditions. If the doctor can't be sure it's epilepsy at this stage, the patient may need to spend time in hospital.

Video telemetry

"If people are having frequent seizures and we can't make a diagnosis, we bring them into hospital for video telemetry," says Dr Clough. "This is where we have them under surveillance by video camera and at the same time monitor their brain activity."

This can take up to a week. It allows doctors to match up what the seizure looks like with what is happening in the brain. It can also rule out other conditions that might be causing the seizures, such as an abnormal heart rhythm.

Diagnosis

The doctor should be able to identify what kind of seizures you're having, such as complex partial seizures or tonic-clonic generalised seizures (see  Types of seizure for more information). They may also be able to find the cause.

In around 30% of people with epilepsy, the cause is never discovered. If this is the case, they will be diagnosed with idiopathic epilepsy.

If you're diagnosed with epilepsy, your care can be shared between your GP and a hospital-based epilepsy service, although this may vary across the country.

Treatment can include taking anti-epileptic drugs and making changes to your lifestyle to avoid triggers, such as tiredness. Up to 70% of people with epilepsy stop having seizures when they take anti-epileptic drugs.

Go to Health A-Z for more on epilepsy and treatment.

Medical Review: December 12, 2008

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