Epilepsy Terms
What is the difference between the terms "ictal," "postictal" and "interictal"?
The term “ictal” is usually used to describe an ictal event. An ictal event is a seizure. The term “postictal” is an adjective referring to a period of time. We're curious to know what the behavior is of the person after the seizure, so ask, “What is the postictal behavior? Is the person lazy, lethargic, or did they snap out of it immediately and start conversing?” Postictal behavior is a way we use the term “postictal.” In terms of “interictal,” we are often looking at the interictal period of time: "How much time occurred between the different seizure events?"
What is a "focal" seizure?
With epilepsy, a focal seizure is one that arises from a very distinct localization in the brain. So, if you have an epileptic seizure that always starts with your right hand shaking, then this would be a focal seizure that would be localized to the motor cortex on the left hemisphere.
What is a "photosensitivity" seizure trigger?
With epilepsy, a photosensitivity seizure trigger involves a type of seizure whereby bright light stimulates that person who has epilepsy to have a seizure. Now, photosensitivity refers to the fact that it is a photo induced seizure. Usually, a strobe light is used in this case to provoke the seizure and the circuitry involved would be the retina of the eye, the lateral geniculate of the thalamus, and the visual cortex which is found in the occipital cortex.
What is a seizure "aura"?
With epilepsy, a seizure aura comes from the Latin term meaning breeze. Therefore a breeze or an aura is a signal that arises just prior to the actual onset of the seizure. The aura could be smelling some kind of smoke or burning food. This is one type of aura. Sometimes if you have an audiogenic kind of a seizure, you can hear a loud ringing bell, maybe a horn blowing. So, an aura is something that a person with epilepsy would commonly occur just prior to the onset of the epileptic seizure.
What is an "automatism"?
Automatisms are these automatic type of behaviors that occur only onset of a seizure. Lip-smacking is something that is a very common automatism or shaking of the hand.
What does "tonic" mean in relation to epilepsy?
With epilepsy, ‘tonic' refers to the powerful muscular excitation that occurs throughout the body. So, in our normal movements, we have a flexor and an extensor muscle around every joint, with one of these muscles relaxing while the other is contracting. During a tonic seizure or tonic activity, we have both muscles contracting at the same time, which leads to both arms and both legs being outstretched. This is due to severe muscular contraction of both extensors and the flexors.
What does "clonic" mean in relation to epilepsy?
With epilepsy, clonic refers to another type of movement of the arms and legs where we often have very rapid flexion. For example, for the arm, the largest flexor muscle is the bicep. A clonic movement for this would be a flexing movement of the arm. This is in contrast to the term "tonic" where we would have an extension of the arm.
What is a "tonic-clonic" seizure?
With epilepsy, a tonic-closure seizure involves a lot of the activity or behavior of the body during a large seizure. One of these generalized epileptic seizures usually starts out with a tonic movement, and then it progresses into the clonic movement. So, there's first this extension with a lot of shaking and trembling, and then the clonic movement starts in, where the flexor activity occurs.
What is "clustering" in relation to epilepsy?
With epilepsy, ‘clustering' occurs when a person will maybe go a month without having any seizure, and then in the morning, they'll have a complex partial seizure. Then, later in the same day they could have two or three more seizures. So, when you go for quite a while without having seizures, and then in one day you have multiple seizures which seem to be in the same 24-hour time period, this is referred to as the "clustering" of seizures.
What is "status epilepticus"?
With epilepsy, ‘status epilepticus' is the most severe type of seizure that one could have. It is so severe that the muscles of the body are all contracting for a very long period of time; this could actually lead to death because you can't breathe and your tongue gets stuck in your throat. Therefore status epilepticus is something that most clinicians try to avoid in their patients. In most people by treating them with various drugs, the seizures never get to be that severe. However, status epilepticus is the most extreme type of seizure that you can have as it could lead to death.
What is a "febrile seizure"?
Febrile seizures are seen in young infants, usually under the age of three. These are seizures that occur as a result of a high fever when that individual is fighting some kind of an infection. The high fever sends the individual into having a seizure. Now, febrile seizures themselves are not epilepsy. Usually one or two cases of these febrile seizures, and then the person lives the rest of their life without ever having another seizure. However, there are other cases now where there may be, in fact, a link between febrile seizures and seizures in adulthood.
