Common neurological disease, epilepsy nearly affects 1% of the population.
Open / close summary

The name ‘epilepsy’ comes from a Greek word meaning ‘struck by surprise’, reflecting the sudden and unpredictable onset of seizures.

In France, 600,000 people are affected by this chronic neurological disease, which can manifest itself in different ways depending on the area of the brain affected. Around 50% of epilepsies begin before the age of 10.

Epileptic seizures are the manifestation of excessive cerebral activity resulting from ‘hyperexcitation’ of the nerve cells – the neurons of the cerebral cortex – and their synchronisation.

A distinction is made between (i) generalised epilepsies, affecting around 1/3 of patients, when all the neurons in the cortex are recruited from the outset, and (ii) focal epilepsies, which begin in a specific region of the brain.

Epilepsy can have various causes, such as a brain lesion, in which case it is known as structural epilepsy (formerly symptomatic), or it can be genetic (idiopathic epilepsy), metabolic or self-induced.

There is not one epilepsy but several epilepsy syndromes of varying severity, defined by the age of onset of seizures, their cause, nature and frequency, and response to drug treatment.

Diagnosis of this disease is based on clinical symptoms reported by the patient and his or her family during epileptic seizures and on analysis of an electroencephalogram (EEG), i.e. a recording of the electrical activity of the brain’s neurons. Cerebral MRI can also be used to detect damage to the cortex.

Today, drug treatments are effective in more than 2/3 of patients, although 30% are drug-resistant. Surgery should be considered for these patients, because when the seizure source can be identified and operated on, patients may no longer have seizures.



There are many causes of epilepsy, classified according to international criteria: structural causes (or symptoms of damage to the cortex), genetic causes, metabolic causes (e.g. an enzyme disease), autoimmune causes (inflammation localized in the brain). Sometimes, no cause is identified.

Whatever the origin, epilepsies can be generalised (about 1/3 of cases) to the entire cerebral cortex or focal (partial), i.e. restricted to a precise, delimited area of the brain in 2/3 of patients.



An epileptic seizure is a transient clinical manifestation linked to abnormal electrical activity in a specific region or throughout the brain.

The diagnosis of epilepsy is based on questioning patients and their relatives, watching a video of their seizure, and electroencephalic (EEG) recording between seizures, and sometimes during a seizure. Identifying the cause requires additional data: brain imaging, and sometimes biological tests (blood samples, or even a lumbar puncture).



The treatment of epilepsy depends on whether it is focal or generalised.

Anti-epileptic drugs control seizures in more than two-thirds of patients. Sometimes, several drugs may be combined to control the epilepsy.

In some forms of epilepsy, treatment can be stopped after several years.

When focal epilepsy is not controlled by anti-epileptic drugs, surgery should be considered.


Read our press pack: ‘Epilepsy: research at the Institut du Cerveau’.


Last updated May 2024.