A seizure occurs when the brain receives a burst of abnormal electrical signals that temporarily interrupt its normal electrical function. There are many different types of epileptic seizure. The signs of a seizure are varied and include occasional interruptions to consciousness during absence seizures (small generalised or petit mal seizures), brief involuntary muscle jerks with no loss of consciousness (myoclonic seizures) and violent convulsions with loss of consciousness (grand mal or tonic clonic seizures).
Epilepsies can occur as the result of a stroke or head injury, among other causes, or may be provoked by a brain tumour or degenerative condition such as Alzheimer’s Disease. Around one third of epilepsies are due to genetic factors. Only a small proportion of these epilepsies are inherited – many develop as the result of a genetic mutation occurring for the first time (de novo mutations). Sometimes, however, the cause of epilepsy remains unclear.
Not every person who has one or more epileptic seizures has epilepsy. Epilepsy is not usually diagnosed until the person has had several spontaneously occurring seizures with no identifiable trigger. Epilepsy is not a uniform condition but rather a group of disorders with very different symptoms, progressions and causes.
Truths and misconceptions
Epilepsy is a health problem that is often met with misconceptions and prejudice. Some true statements about epilepsy are:
- Epileptic seizures are not always dramatic and involve jerks and convulsions. Sometimes the signs are almost undetectable, for example brief absences, numbness or tingling.
- Most people with epilepsy do not have intellectual disabilities.
- Epilepsy is not a mental (psychiatric) illness but a neurological disorder.
- Over 90% of epilepsies are not hereditary.
- People with epilepsy have different characters just like everyone else; there are no typical character traits like particularly high intelligence.