Absence

= Absence =

Absence, in a medical context, often refers to a type of seizure known as an "absence seizure." These seizures are characterized by brief, sudden lapses in attention and awareness. They are a form of generalized onset seizures, meaning they affect both sides of the brain from the onset. Absence seizures are most commonly observed in children, but they can occur at any age.

Clinical Presentation

Absence seizures are typically brief, lasting only a few seconds, and may occur multiple times a day. During an absence seizure, the individual may appear to be staring blankly into space, and they may not respond to external stimuli. Other signs can include:

• Sudden stop in motion without falling
• Lip smacking
• Eyelid fluttering
• Chewing motions
• Small movements of both hands

After the seizure, the person usually resumes their previous activity without any postictal confusion, which is a state of confusion that can occur after other types of seizures.

Epidemiology

Absence seizures are most common in children between the ages of 4 and 14. They are slightly more prevalent in girls than in boys. The exact prevalence is difficult to determine, but they are a common form of epilepsy in childhood.

Pathophysiology

The pathophysiology of absence seizures involves abnormal electrical activity in the brain. These seizures are thought to originate in the thalamus and involve the thalamocortical circuitry. The characteristic 3 Hz spike-and-wave discharges seen on electroencephalogram (EEG) are a hallmark of absence seizures.

Diagnosis

Diagnosis of absence seizures is primarily clinical, supported by EEG findings. The EEG typically shows generalized 3 Hz spike-and-wave discharges during the seizure. A thorough history and physical examination are essential to differentiate absence seizures from other types of seizures or non-epileptic events.

Treatment

The mainstay of treatment for absence seizures is antiepileptic medication. The most commonly used medications include:

• Ethosuximide: Often the first-line treatment for absence seizures.
• Valproic acid: Used when ethosuximide is not effective or tolerated.
• Lamotrigine: Another option, particularly if there are other types of seizures present.

Lifestyle modifications, such as ensuring adequate sleep and avoiding known seizure triggers, can also be beneficial.

Prognosis

The prognosis for children with absence seizures is generally good. Many children outgrow the seizures by adolescence. However, some may develop other types of seizures or continue to have absence seizures into adulthood. Regular follow-up with a healthcare provider is important to monitor seizure control and medication side effects.

Differential Diagnosis

It is important to differentiate absence seizures from other conditions that can cause similar symptoms, such as:

• Daydreaming: Often confused with absence seizures, but lacks the EEG changes.
• Attention-deficit/hyperactivity disorder (ADHD): Can cause inattentiveness but is not associated with the characteristic EEG findings.
• Complex partial seizures: These can involve altered awareness but typically last longer and have a postictal state.

Conclusion

Absence seizures are a common form of epilepsy in children, characterized by brief lapses in awareness. With appropriate diagnosis and treatment, most children can achieve good seizure control and lead normal lives. Ongoing research continues to improve our understanding and management of these seizures.