Classification of Seizure Types

Generalised Seizures

(seizures that affect the whole brain)

Absence Seizures

Absence seizures mostly affect children of primary school age and consist of brief (up to 30 seconds) periods of loss of awareness which may happen many times a day. The child appears to stare vacantly, the eyes may flutter or turn upwards. The child is unaware of his/her surroundings, but recovery is prompt. Absence seizures are often mistaken for daydreaming or lack of concentration and can disrupt learning by creating gaps in information received.

Tonic–clonic Seizures

Tonic–clonic seizures are recognised by a sudden loss of consciousness, the body stiffens (tonic phase) quickly followed by general muscle jerking (clonic phase). Breathing may appear difficult and the person may bite the tongue. The seizure ends when the jerking stops, muscles relax and normal breathing returns. Tonic–clonic seizures usually last 1–3 minutes, seldom longer. There may be a period of confusion after the seizure and the person may want to sleep.

Myoclonic Seizures*

Myoclonic seizures are characterized by brief uncontrollable jerks of a muscle or muscle group. These seizures usually occur soon after waking or before going to bed when the person is tired.

Tonic Seizures*

Tonic seizures are generalized seizures causing the muscles to stiffen and if the person is standing they will fall quite heavily to the floor. This type of seizure often causes head injury and it is advisable for the person to wear a protective helmet to avoid constant injury.

Atonic Seizures*

This form of seizure activity can be characterised by a sudden and very brief loss of ability to stand or sit upright. Usually the person nods his head, slumps forward, or actually falls to the floor motionless. After the seizure the person may seem a little disorientated for a few seconds. They can be called “drop attacks”.

Focal Seizures

(seizures that occur in one part of the brain)

Focal Seizure with Awareness*

The symptoms the person experiences will depend on the function that part of the brain controls. The person remains fully conscious throughout the seizure.
This type of seizure may begin with a stiffening or twitching of an arm or leg, or the person may lose the ability to speak. This type of seizure usually lasts for less than a minute and then the person recovers.

Focal Seizures without Awareness

These seizures vary widely. Often there is a loss or distorted awareness of surroundings. Inappropriate actions such as chewing movements and fiddling with clothing or aimless wandering may occur. After the seizure there may be a short period of confusion.

Note: It is not unusual for people to have more than one type of seizure.
*Reprinted from Epifile with the permission of Epilepsy Australia August 2002

Nocturnal Seizures

There are a small number of people who only have nocturnal seizures (ie seizures occurring in relation to sleep.) The majority of these occur either just after falling asleep or before waking hours. Although the mechanism is poorly understood, there is evidence that sleep activity may influence epilepsy activity. The majority of patients who have only nocturnal seizures generally have idiopathic epilepsy. If the person maintains this pattern of only having seizures during sleep for several years, the probability of the seizures also becoming a daytime occurrence is small. Most of the nocturnal seizures are tonic-clonic in type.

Seizures may occur at any time during the sleep cycle. However, there are three specific times at which they occur most frequently:

a) within the first or second hour after going off to sleep (early nocturnal seizures),
b) one to two hours before the usual time of wakening (early morning seizures),
c) within the first hour or so after awakening (early morning seizures).

Seizures which occur in association with sleep have been classified as hypnos-epilepsy or sleep epilepsy, since such seizures may also occur during an afternoon nap.

The drug treatment of nocturnal seizures is similar to seizures of a similar nature that occur during the waking hours. Positive treatment of seizures is based on the type of seizures rather than on the time of occurrence.

Sleep: Too Much Too Little

Non-alertness, drowsiness, or light sleep (as in falling asleep or in awakening) is a time in which some seizures are most apt to occur. This is especially true with psychomotor attacks, myoclonic seizures, and atypical absence spells. Since a normal sleep pattern cycles from deep to light sleep states, seizures may relate to these cycles during the night as well as during daytime naps. People who experience seizures only at night with sleep (nocturnal seizures) for the first few years of their seizure problem are often unlikely to experience a daytime attack.

They may experience few restrictions on employment and driving, and very few restrictions during the daytime. Most seizures that occur during sleep as well as during the daytime wakening hours are but sleep–altered variations of the same seizure problem. Unlike purely nocturnal seizures, which are limited to the sleep state, the latter group are a nightmare accentuating of a seizure problem.

Sometimes the tendency toward seizures in sleep may be reduced by increasing the evening dosage of anticonvulsant medication. If the seizures occur with falling asleep in the early evening, the supper dosage may be increased; if they tend to occur in the early morning around the time of awakening the approach may be to increase the bedtime dosage of medication or to use a longer–acting anticonvulsant or a time–release capsule.

It has been suggested in the past that sleeping with the light on and with a ticking clock or radio in the room may also decrease the tendency toward seizing. This is at least worth a trial.

Regular sleep habits are important, especially to those with sleep related seizures. Seizures may be triggered by missing sleep or sometimes even by getting too much sleep. Some people who cannot fall asleep may use sedatives that tend to aggravate the seizures problem. They may be drowsy the next day, which itself aggravates the seizure tendency. They may resort to coffee or stimulant medications to overcome the drowsiness, a practice that can exacerbate some seizures, especially if the stimulating substance is used in excess.

Problems in falling asleep may be overcome by increasing the evening medication, by avoiding the use of stimulating substances, especially in the late afternoon or evening, by calm evening activities, or by using a mild bedtime sedative and behavioural training to establish a more efficient sleep pattern. Drowsiness will almost certainly increase daytime seizures. Sometimes stimulants and caffeine containing substances given early in the day may be used to increase alertness and to overcome the seizure provoking tendency.

However be cautious that the substances themselves do not trigger seizures or do not excessively interfere with the absorption of the anticonvulsants. Behavioural training approaches may be used to maintain optimum alertness during the day as well as to interrupt some of the seizures that do break though.

Reprinted from: “Other Approaches in Seizure Management”; “Learning about Epilepsy” by William D Svoboda MD