What is an Absence Seizure?

Absence Seizure Explained: Symptoms, Risk Factors & Medications

An absence seizure is a sudden, generalised, non-motor seizure that results in an abrupt loss of awareness. Every year, it affects 6 to 8 out of every 100,000 children aged below 15 years. In general, absence seizures tend to pass unnoticed due to their subtle nature and rapid resolution.

Although, in most cases, absence seizures are harmless, they can disrupt daily life if they start occurring recurrently.

Keep reading to learn more about this condition, including its symptoms, causes, diagnosis, and treatment.

What is Meant by Absence Seizure in Children?

Absence seizures, previously referred to as petit mal seizures, are short, generalised seizures that result in a sudden loss of awareness. It is most commonly observed in children and usually occurs as a staring spell or short unresponsiveness that lasts for 3 to 15 seconds.

During an attack, the individual will stare blankly into space, freeze suddenly in conversation or activity, and resume quickly as if nothing is wrong. It is frequently overlooked by others, mainly since they do not include convulsions or spectacular movements.

Usually, such seizures tend to occur more in babies or children than in adults.

What are the symptoms of absence seizure?

Absence seizures are characterised by sudden, transient loss of consciousness that is easily confused with inattention or daydreaming. They usually last for less than 30 seconds and sometimes go unnoticed, particularly in kids.

The following are the most frequent symptoms seen in absence seizures:

• An abrupt, empty stare, or "far-off look", when the individual appears to be absent-minded for a brief time.
• The child's awareness and responsiveness to their environment are significantly impaired during the attack.
• They can suddenly stop talking, walking, or any other current task.
• Repetitive mouth movements may occur unconsciously.
• Quick blinking or fluttering of the eyelids is a frequent indication, particularly in children.
• The individual may rub their fingers together or perform sudden, subtle hand gestures.
• Minor head movements, along with repetitive nodding, can be observed.
• Minor adjustments in posture, such as slight leaning, may occur during the episode.
• The individual often continues their activity without being aware of what happened.
• In contrast to other types of seizures, absence seizures generally do not lead to confusion, drowsiness, or headaches afterwards.
• Some kids may have several seizures each day, which can interfere with learning or daily activities.

What are the causes and risk factors of absence seizures?

Absence seizures will occur following abnormal electrical signals in the brain and can be affected by both genetic and environmental factors. Here are the major issues or risk factors:

• Abnormal Brain Activity: A Absence seizures are caused by sudden, generalized bursts of electrical activity in the brain, which on an EEG appear as a characteristic 3 Hz spike-and-wave pattern.
• Neurotransmitters: Altered levels of chemical messengers (neurotransmitters) may affect communication between brain cells, contributing to seizure activity.
• Genetics: There is a relatively strong genetic predisposition. Research shows known patterns of mutations in terms of ion channel-related genes that may also run in families, particularly in genetic cases of juvenile absence epilepsy (JAE).
• Age: Absence seizures are most commonly found in children between the ages of 4 and 14, peaking in the age range of 6-7.
• Gender: Absence seizures were seen more in girls than boys.
• Family History: Children who have close relatives (i.e., parents and siblings) with epilepsy are at increased risk.
• Medication: Certain antiseizure drugs, like phenytoin, carbamazepine, or gabapentin, are known to cause absence seizures.

What is the diagnosis process for absence seizures?

Diagnosing absence seizures requires a combination of thorough clinical assessment and special tests to effectively identify seizure activity and eliminate other diseases. Some of the primary diagnostic techniques are:

1. Clinical Assessment : A neurologist will start by screening the symptoms, general health, medications, and medical history extensively. Then, they will ask the patients or their family members questions regarding the detailed descriptions of the seizure attacks to familiarise themselves with their features and frequency.
2. Electroencephalogram (EEG) : This test measures the brain's electrical activity using electrodes on the scalp. Absence seizures cause a specific pattern of brain waves, which may be noticed during the examination by hyperventilation or flashing lights.
3. Hyperventilation Test : As part of the EEG, rapid breathing (hyperventilation) might be induced because it has a tendency to trigger absence seizures, allowing seizure activity to be recorded on the EEG.
4. Imaging of the Brain (MRI or CT Scan) : Brain imaging (MRI) is not typically required for classic childhood absence epilepsy but may be used to rule out other structural causes if the seizure type is atypical or the patient does not respond to standard treatment.
5. Other Laboratory Tests : Blood and urine tests can be done to detect underlying metabolic or systemic causes of seizures.

What is the List of Medications Provided for Absence Seizures?

Mentioned below is the list of antiseizure medications that are commonly prescribed to manage absence seizures:

• Ethosuximide (Zarontin)
• Valproic acid (Depakene, Stavzor)
• Lamotrigine (Lamictal)
• Topiramate (Topamax)
• Zonisamide (as adjunct therapy)
• Levetiracetam (as adjunct therapy)

Observing your child for symptoms is crucial for early diagnosis and treatment. Taking into account genetic and family history risk factors can also help detect absence seizures early. With appropriate treatment, many children stop having them by the time they reach adolescence and enjoy a normal, healthy life.