Epilepsy

General information about epilepsy

Epilepsy is a disorder of the brain that predisposes a person to recurrent unprovoked seizures.

The brain is made up of nerve cells that communicate with one another by electrical and chemical contact. An electrical discharge disrupts normal nerve cell activity. This causes a change in brain function and behaviour, triggering a seizure.

Neurons are cells that communicate with one another by electrical contact. An epileptic seizure can be likened to an electrical short circuit in our brain, causing an electrical surge.

The starting point for this surge is a “scar”.

This “scar” can be many things, such as a brain injury, a genetic trait, a malformation, etc. Sometimes, despite current technology, we are unable to identify this starting point or scar, which does not mean that it does not exist. This short circuit is variable: it can be limited to one area, giving rise to more subtle symptoms, or more extensive, with more severe symptoms, such as a convulsion.

Etiology / Risk factors

There are 3 broad categories:

Acquired epilepsies (structural/metabolic): perinatal anoxia, prior stroke, head injury, tumour, prior meningitis/encephalitis, any disease that causes brain damage … (known structural abnormality)
Hereditary/genetic epilepsies
Unknown (> 50%)

Operational (practical) clinical definition of epilepsy

Diagnosis is based on a history and neurological examination, sometimes supported by the results of paraclinical tests (EEG, MRI, etc.). However, there is an operational definition of epilepsy:

Epilepsy is a disorder of the brain defined by any of the following conditions:

At least two unprovoked (or reflex) seizures occurring more than 24 hours apart
One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
Diagnosis of an epilepsy syndrome

Epilepsy is considered to be resolved for patients who had an age-dependent epilepsy syndrome but are now past the applicable age or those who have remained seizure-free for the last 10 years, with no seizure medicines for at least 5 years.

Electroclinical syndromes and other epilepsies

Epilepsy is a spectrum condition with a wide range of seizure types or epilepsy syndromes. This is why we often speak of epilepsies.

An epilepsy syndrome is a distinctive disorder that is identified on the basis of seizure type, seizure location, EEG characteristics, the child’s age when seizures begin and related symptoms. The cause, if it is known, can also be a feature that defines the syndrome.

 

We would like to highlight Catherine Vigneault’s contribution to the writing of the section on epileptic syndromes.

References:
M. Bureau et autres. Les syndromes épileptiques de l'enfant et l'adolescent (5ème édition), John Libby Euronext, 2013, 644 pages.
ABOUT KIDS HEALT. Syndromes épileptique
ALLIANCE CANADIENNE D'ÉPILEPSIE. Syndromes épileptiques