What is epilepsy?
Epilepsy is a chronic neurological disorder in which seizures are caused by a disruption of the electrical activity in the brain. It is one of the most common and disabling neurological conditions (Epilepsy Action Australia 2020), yet the causes are still not well understood (Stafstrom & Carmant 2015). Epilepsy involves many different types of seizures including changes to sensation, awareness, behaviour or movement. Not all seizures involve convulsions (Epilepsy Action Australia 2020).
While the underlying cause of epilepsy is known for around half of all people with the condition, the cause is never identified for many sufferers. Known causes include injury and stroke, prolonged oxygen deprivation, brain infections and tumours, neurodegenerative conditions (such as dementia) and congenital abnormalities. People with or without epilepsy can also suffer from pseudoseizures. Superficially these appear to be seizures, but are a result of psychological causes.
Box 1: Classifying epilepsy
In 2017, the International League Against Epilepsy (ILAE) revised its classification of seizures. The new basic seizure classification is based on 3 key features: where seizures begin in the brain, the level of awareness during a seizure, and other features of seizures such as movement (Epilepsy Foundation 2016; Deloitte Access Economics 2020).
Where seizures begin
Seizures that start in an area on one side of the brain are known as focal seizures, and seizures that involve both sides of the brain are known as generalised seizures.
A seizure that starts on one side of the brain and spreads to both is known as a focal to bilateral seizure.
A seizure of unknown onset can be given the appropriate name later on once an origin has been established.
The level of awareness during a seizure
The description of awareness applies primarily to focal seizures, as generalised seizures are presumed to affect awareness.
Focal aware applies if the person having the seizure is aware, even if they are not responsive.
Focal impaired awareness applies if awareness was affected at any point during the seizure.
It is not always possible to know whether awareness was affected, so the awareness term may not always be used.
The terms motor and non-motor are used to distinguish seizures that do and do not involve movement such as twitching or muscle stiffening. These terms are applicable to both focal onset and generalised onset seizures.
Epilepsy can be treatable with pharmaceuticals and 70% of people with epilepsy can become seizure free with medication (WHO 2019). Medication is not wholly effective or suitable for controlling seizures in the remaining 30%. Whether seizures are successfully controlled by medication or not, an epilepsy diagnosis requires lifelong management, and can impact work, education and health as a result. Additionally, roughly half of the people with epilepsy have coexisting physical or psychiatric conditions (WHO 2019). Comorbidity in epilepsy is associated with poorer health outcomes, increased health care needs, decreased quality of life and greater social exclusion.
Deloitte Access Economics 2020. The economic burden of epilepsy in Australia, 2019-20.
Epilepsy Foundation 2016. 2017 Revised Classification of Seizures. Viewed 8 Jan 2021, 2017 Revised Classification of Seizures | Epilepsy Foundation.
Epilepsy Action Australia 2020. Epilepsy: The Facts. Viewed 8 Jan 2021, About Epilepsy | Epilepsy Action Australia.
Stafstrom CE, Carmant L 2015. Seizures and epilepsy: an overview for neuroscientists. Cold Spring Harbor Perspectives in Medicine 5(6). doi:10.1101/cshperspect.a022426.
World Health Organisation 2019. Epilepsy: a public health imperative. Geneva: World Health Organization.