Epilepsy is a disorder of the brain characterized by a predisposition to epileptic seizures which are due to abnormal electrical activity in the brain which may manifest itself as a disturbance of consciousness, behaviour, emotion, motor function, or sensation.
Seizures can vary from the briefest lapses of attention or muscle jerks, to severe and prolonged convulsions i.e. violent and involuntary contractions, or a series of contractions, of the muscles. Seizures can also vary in frequency, from less than one per year to several per day.
Epileptic seizures that are not of primary cerebral origin may occur in people who do not have epilepsy if they are exposed to a transient noxious stimulus, such as hypoxia or hypoglycaemia, caused by a disorder originating outside of the brain.
Epilepsy is not just a single condition. Approximately one third of people with epilepsy in the UK have an anatomically identifiable cause, this is described as symptomatic epilepsy and is the most common cause of epilepsy in older people. Epilepsy is also a feature in genetic disorders (more than 200), other identifiable causes include:
- cerebrovascular disease
- cerebral tumour
- post-traumatic epilepsy
- perinatal brain injury
- brain infections
- cortical malformation
- vascular malformation.