What is epilepsy?
Epilepsy is a neurological condition affecting about 2-3% of people at some time in their lives. People with epilepsy experience recurrent, unprovoked seizures which are caused by a brief change in the electrical and chemical activity in the brain. These seizures can result in the person experiencing unusual feelings, loss of awareness, or unusual movements and postures and can last from a few seconds to several minutes. The part of the brain affected determines what a person experiences during the seizure.
What are seizures?
There are many different types of seizures, which are divided into two groups – focal (or partial) seizures where the seizure starts on one side or in one specific place in the brain, and generalised seizures where the seizure involves both sides of the brain simultaneously. It is important to work out what type of seizure(s) a person might be experiencing as this can affect which medications a doctor will prescribe and what the expected long term outcome will be.
The following description and terminology of seizure types are those most commonly used today, from the official classification for seizures by the ILAE (International League Against Epilepsy) published in 1981. The current classification commission is revising the description and classification of seizures and epilepsies. Details about the new terminology of seizure types can be found on the ILAE web site.
Focal (Partial) seizures
Simple partial seizures
These seizures originate from one area of the brain and do not result in impaired awareness. They may manifest as funny feelings or sensations (eg a funny feeling in the stomach, tingling or an odd sensation in one part of the body), changes in perception (changes in vision or hearing), unusual or unpleasant déjà vus or other tricks of the memory, or stiffness or jerking of a limb. Simple partial seizures (also called auras or warnings) can occur on their own, or may occur before a complex partial or generalized tonic-clonic seizure.
Complex partial seizures
Complex partial seizures also originate from one area of the brain but they do result in alteration of awareness. Sometimes people lose awareness completely, while on other occasions they may retain some awareness of their surroundings, but not be able to respond appropriately or remember anything after the event. Seizures can involve stiffness, jerking or other unusual movements of a part of the body, purposeless movements such as picking at clothes, tapping fingers or lip smacking, incomprehensible speech, or the person may simply sit and stare blankly. People often feel a bit tired and confused after having a complex partial seizure.
A tonic-clonic seizure (sometimes called “grand mal” or a convulsion) is what most people think of when they think of a seizure or fit. In these events the person falls to the ground, loses awareness and becomes stiff and jerks all over. These seizures can last for a couple of minutes, after which the person may be confused and sleepy.
Absence seizures (previously known as “petit mal”) normally start in childhood and involve a brief (usually 5-10sec) staring spell during which the person is unaware. They may have some eyelid fluttering, eye rolling or automatic movements with their fingers or mouth. Absence seizures can occur many times a day and can be difficult to distinguish from day dreaming.
Myoclonic jerks are very quick twitches or muscle jerks that can involve the whole body, just one limb or a single group of muscles. Myoclonic jerks may cause someone to drop something they are holding, or to fall down if the jerk involves the legs.
Tonic and Atonic seizures
Tonic and atonic seizures are often called drop attacks because they may cause the person to suddenly fall to the ground. In a tonic seizure the person becomes very stiff and will fall like a board, whereas in an atonic seizure they become very floppy and “fall like a rag doll”. If the person is sitting an atonic seizure may present as a brief slump or “head nod”. These seizures usually only last a few seconds but people can hurt themselves quite badly as a result of a fall.
What are epilepsy syndromes?
A syndrome is a collection of signs and symptoms which are seen repeatedly in different patients. In epilepsy the signs and symptoms doctors use to identify a syndrome are the age of onset of the seizures, the seizure types, the frequency of seizures and sometimes results from tests such as EEGs or MRIs. Identifying the syndrome helps the doctor work out how best to treat the patient and also provides some information about the expected long-term outcome for the patient.
Some common epilepsy syndromes that you may have heard of are:
Information about Epilepsy Investigations
These web sites also provide good information about seizures and epilepsy in general.