ABSENCE CRISIS: CHARACTERISTICS, CLASSIFICATION, TREATMENT - NEUROPSYCHOLOGY - 2025

The absence seizures are an episode in which the child loses consciousness, it falls to stare, as if looking at the horizon and unresponsive to any stimulus. These episodes last about 10 seconds and start and end abruptly.

This type of crisis is not very common, between 2% and 8% of people with epilepsy suffer it, especially in children, although it can also occur in adults. The cause of this type of crisis is not yet known, although it seems that the genetic component plays an important role in the development of this condition.

The prognosis is quite favorable, in 65% of cases the seizures respond well to treatment and disappear during adolescence without leaving neuropsychological sequelae.

Characteristics of absence seizures

Absence crises, formerly known as petit mal, are episodes in which the child loses consciousness, does not respond to stimuli and leaves his gaze lost, as if he could not see.

For example, they do not realize that someone is talking to them and they do not answer, it can even happen while they are talking and they suddenly stop talking. When the crisis ends, the person usually does not remember that anything happened and continues doing the same thing that she was doing before.

The episodes usually last about 10 seconds and end abruptly, when the child "wakes up." The attacks are quite frequent and can occur between 1 and 50 times a day, especially if the child is doing some exercise.

People who have absence seizures usually do not also have seizures with tonic-clonic seizures (commonly known as epileptic seizures), although they may have suffered them before or suffered them after developing absence seizure epilepsy.

Classification

There are two types of absence seizures:

Simple absence crisis

These crises are characterized by the person remaining still without responding to any stimulus for approximately 10 seconds.

These crises are so rapid that, often, the person does not even realize that they have occurred, and can be mistaken for a temporary lack of attention.

Complex absence crisis

Complex absence seizures differ from the previous ones in that they are longer, last about 20 seconds, and the person does not stay still, they can make movements or gestures such as blinking repeatedly, moving their mouth as if they were chewing or moving their hands.

Symptoms can be so mild that a person can have the disease for years without realizing it. In children it is often confused with an attention deficit and the first sign that something is wrong is usually that they are behind in school.

Between 2% and 8% of the population with epilepsy suffer this type of seizure. Absence seizures usually begin between 4 and 8 years of age in children who do not have any neurological disease and who have normal levels of intelligence. It can also occur in adolescents and young adults, but it is much less common.

All epilepsies occur because there is abnormal activity in the patient's brain.

Although the exact cause of this abnormal activity is not known, it is known that the genetic component is quite important, since 1/3 of the relatives of children with absence seizures have also suffered this type of absence and it has been found that a 10% of the siblings of these children also develop the disease.

Patients show abnormal activity on EEG with a spike-wave discharge of 1.5 to 4 Hz (cycles per second) in both cerebral hemispheres. With other neuroimaging techniques, such as computed tomography or magnetic resonance imaging, no brain abnormality is seen.

Treatment

Currently there is no treatment to cure crises, but there is to control them. Patients are usually prescribed ethosuximide (brand name: Zarontin), valproic acid (brand name: Depakote), or lamotrigine (brand name: Lamictal).

Valproic acid has the advantage that it also serves to treat tonic-clonic seizures, which is why it is especially indicated in patients who have these two types of seizures.

If the absence seizures are severe and cannot be controlled with a single drug, the administration of two of them is usually combined, usually ethosuximide and valproic acid.

Clinical trials are currently underway to test the efficacy of other drugs in the treatment of absence seizures. The drugs under study are levitaracetam (trade name: Keppra), topiramate (trade name: Topamax), and zonisamide (trade name: Zonegram), among others.

Forecast

Absence seizures do not have to leave cognitive consequences, although children with this type of epilepsy are often behind in school and have social problems derived from the seizures.

The prognosis of children with absence seizures is quite favorable, 65% of patients with this type of epilepsy respond well to treatment and the seizures usually disappear in adolescence. Although in some cases the seizures can last into adulthood.

Diagnosis of absence seizures

Absence seizures are difficult to identify, especially the simple ones, so people often have the disease for years before it is diagnosed.

In children, the delay in school with respect to their peers is usually the first indicator, although it is necessary to rule out other problems since this sign can occur in multiple diseases and disorders.

In adults, it is very difficult to realize, the person himself usually thinks that he has had an attentional lapse or that he was daydreaming. Complex absence seizures are easier to identify as some of the following occur:

• Repeated blinks.
• Lip moistening
• Move your mouth as if you are chewing.
• Finger snapping.
• Move the hands.

Once the person, or their parents (in the case of children), realize that a problem occurs, it is important that they see the doctor. Typically, the doctor suspects various neurological disorders and performs an electroencephalography (EEG) to observe brain activity.

The EEG is a painless test that consists of placing electrodes on the scalp that record the electrical activity of neurons. People with epilepsy have a typical activation pattern, called a pico-wave, that can be seen with this test.

Another test, a little more rudimentary, to check if the person has epilepsy with absence seizures is to provoke a seizure. This is usually done by asking you to breathe quickly, as if you were exercising, as seizures are more likely under these conditions.

This test would not be valid to rule out epilepsy, since the seizure may not occur at that time but the person does suffer from epilepsy.

If you notice these signs in yourself or someone close to you, it is very important that you see a doctor to diagnose this or other disorders.

How to differentiate an epilepsy with a seizure of absence of daydreaming

If you have noticed the aforementioned signs in yourself or someone close to you, but you do not know if it is an absence crisis or it is simply that you are daydreaming, I recommend that you read the following table, where the main differences between these two types are exposed of episodes.

References

1. Holmes, GL, & Fisher, RS (September 2013). Childhood Absence Epilepsy. Obtained from Epilepsy Foundation.
2. Sirven, JI, & Shafer, PO (March 2014). Absence Seizures. Obtained from Epilepsy Foundation.