Absence seizures are a type of seizure where the patient has a sudden lapse in consciousness. It is most common in children. The seizure typically lasts 10-30 seconds. The patient then immediately returns to normal activity. Some patients can have several hundred seizures in a day. Around three quarters of children will outgrow them as they reach adolescence and young adulthood.
An absence seizure looks like a brief lapse in attention or “staring into space.” It is often mistaken for daydreaming or just not paying attention. Other symptoms can include:
The patient does not usually remember that anything unusual happened. There is usually no concern for physical harm during these seizures unless one occurs in situations such as driving or cycling.
It can be difficult for parents or teachers to tell whether a child is merely daydreaming or having absence seizures. Some key differences include:
Like other types of epilepsy, absence seizures are because of abnormal activity in the brain.
A person’s genes are believed to play a role in developing absence seizures. How exactly that occurs is not yet understood but is an area of active investigation. Current research points to several possible genes.
It is known that absence seizures occur most commonly in:
Some children may first have a febrile seizure (a seizure that occurs from a high fever with infection) before developing absence seizures.
Some triggers for absence seizures are:
The diagnosis of absence seizures first requires a parent or teacher to suspect something is wrong. The first clue is often that a child starts having trouble at school.
Once brought to a doctor, it is helpful to speak to someone who has witnessed the episodes, as the child will not remember them. The doctor may then request blood tests to look for the cause. The doctor may also request imaging, such as an MRI or CT scan.
The gold standard for diagnosis of absence seizures is an electroencephalogram (EEG). This is usually done by a specialist. The doctor will attach electrodes to the child’s scalp to record brain activity. In a controlled environment at the doctor’s office or hospital, the doctor will then try to induce a seizure. The changes in the EEG will help make the diagnosis.
Medication using anti-epileptic drugs is the treatment form of choice. Some commonly recommended medications include:
Many children with absence seizures will grow out of them in adolescence into adulthood. For these patients, long-term medication may not be needed.