Absence seizures are a type of epilepsy, a neurological condition characterized by abnormal brain activity. These seizures manifest as brief, sudden lapses of consciousness, often appearing as if an individual is simply daydreaming or staring blankly into space. While they can affect anyone, they are particularly common in children, typically emerging between the ages of 4 and 14.
What Are Absence Seizures?
Absence seizures, sometimes referred to as “petit mal” seizures, are characterized by a sudden, temporary interruption of awareness and activity. During an episode, a person may stop speaking mid-sentence, pause an action, or exhibit subtle movements like lip smacking, eyelid fluttering, or chewing motions. These seizures usually last between 5 and 20 seconds, and the person often resumes normal activity without realizing a seizure occurred. Unlike tonic-clonic seizures, which involve convulsions and loss of muscle control, absence seizures rarely cause falls or physical injury.
A child might experience many of these seizures daily, sometimes as often as 10 to 100 times, which can be easily missed or mistaken for inattention or daydreaming by parents or teachers. While most children with typical absence seizures develop normally, very frequent episodes can sometimes interfere with learning, concentration, and memory, highlighting the importance of timely diagnosis and management.
The Genetic Link to Absence Seizures
Absence seizures are primarily considered to have a genetic basis, meaning they tend to run in families. Evidence from twin studies provides strong support for this genetic influence, with a high concordance rate for absence seizures in identical twins. The inheritance pattern is complex, often involving multiple genes and various genetic changes rather than a single gene defect. This is known as polygenic inheritance, where several genes contribute to the predisposition, and environmental factors may also play a role.
While a family history of seizures increases an individual’s risk, not everyone with a genetic predisposition will develop absence seizures. This concept is referred to as reduced penetrance, meaning that even with an altered gene, the condition may not manifest. Research indicates that some genetic changes associated with childhood absence epilepsy involve genes that provide instructions for proteins forming GABAA receptors or calcium channels. These channels regulate electrical signals in the brain, and mutations can lead to overstimulated neurons, triggering seizures.
Identifying Absence Seizures
Diagnosing absence seizures involves a comprehensive evaluation by a healthcare professional. The process begins with a detailed medical history, where the doctor will ask about the characteristics of the staring spells and any other health or learning concerns. This is followed by a physical examination to rule out other potential causes or associated problems.
A primary diagnostic tool is the electroencephalogram (EEG), which measures electrical activity in the brain through electrodes placed on the scalp. During an EEG, specific patterns of brain activity, such as generalized spike-and-wave discharges at approximately 3 Hz (cycles per second), are characteristic of absence seizures. Rapid breathing, or hyperventilation, performed during an EEG can trigger an absence seizure, helping to confirm the diagnosis. In some cases, video EEG monitoring may also be used to observe the behavioral manifestations of the seizures while simultaneously recording brain activity.
Managing and Living with Absence Seizures
The primary approach to managing absence seizures involves anti-seizure medications, which aim to control the frequency and severity of the episodes. Ethosuximide is often the first medication prescribed for absence seizures, and many individuals experience significant improvement with its use. Valproic acid is another commonly used medication, especially for children who may also experience other seizure types, such as tonic-clonic seizures. Lamotrigine is also an option, though some studies suggest it may be less effective than ethosuximide or valproic acid, despite having fewer side effects.
Many individuals, particularly children, outgrow absence seizures by their teenage years. However, some may continue to require medication into adulthood or might develop other seizure types. Ongoing medical management and regular follow-up with a neurologist are important to monitor medication effectiveness and adjust the treatment plan as needed. Avoiding certain triggers, such as hyperventilation or bright flashing lights, can also be beneficial for some individuals.