Causes of epilepsy

Causes of epilepsy

Anyone can develop epilepsy: it happens in all ages, races and social classes. Epilepsy is the symptom of an underlying cause but the reasons why some people develop it are not straightforward. There are many possible causes and the cause is not always found. 

A person’s seizure threshold often plays a key role in whether they will develop epilepsy. The causes of epilepsy can be put into three main groups:

1. idiopathic (primary) epilepsy
2. symptomatic (secondary) epilepsy
3. cryptogenic epilepsy

Idiopathic epilepsy

This is when the epilepsy is likely to be due to a genetic tendency, that could have been inherited from one or both parents, and this genetic tendency makes epileptic seizures likely to happen.

Symptomatic epilepsy

This is when there is a known cause for a person’s epilepsy, such as a head injury, infections like meningitis, the brain not developing properly, a stroke, or a scar or tumour on the brain. Brain scans, such as Magnetic Resonance Imaging (MRI), may show the cause.

Some symptomatic epilepsies may happen because of a genetic abnormality, such as Tuberous Sclerosis, which causes structural abnormalities in the brain and other organs.

Cryptogenic epilepsy

This is when the cause for a person's epilepsy has not yet been found, despite investigations.

What are seizure thresholds?

A seizure threshold is our individual level of resistance to seizures. We all have a seizure threshold and any of us have the potential to have a seizure. However some people will be more likely to have a seizure than others. Our seizure threshold is one part of our genetic make up which can be passed from parent to child. Therefore the chance of you having seizures may depend on the seizure thresholds of both your parents.

Low seizure thresholds

If you have a low seizure threshold you are more likely to suddenly start having seizures for no obvious reason, than someone with a high seizure threshold.

High seizure thresholds

If you have a high seizure threshold this means your brain is more resistant to seizures and so you are less likely to have one. However, damage to the brain (for example from a severe head injury or an infection) could lower your seizure threshold; making you more likely to have a seizure.