What is an absence seizure?
Absence seizure (previously called petit-mal) is a form of generalised seizure. It mainly occurs in children and young people. It is uncommon in adults. Many people associate epilepsy with the dramatic 'convulsive' type of seizure. Absence seizures are not like this. They are often not noticed for some time as it can appear that the affected person is simply daydreaming. The following gives a typical example.
The person has a brief loss of consciousness (an 'absence') for a few seconds. They do not fall, but may pause in what they are doing. Their face often looks pale with a blank expression. They may look dazed, the eyes stare, and the eyelids may flutter a little. Sometimes their head may fall down a little, or their arms may shake once or twice. Each seizure usually starts and finishes abruptly. The person is not aware of the 'absence', and resumes what they were doing.
Absence seizures may not be noticed by parents or teachers for some time as they usually last just a few seconds. It is common to have several absence seizures per day. If they are frequent, a child's education may suffer as they will not be able to concentrate on lessons.
What causes absence seizures?
No underlying cause can usually be found in the brain. The bursts of abnormal electrical activity usually occur 'out of the blue'. Why they start, or continue to occur, is unclear. What seems to happen is that the brain develops a low threshold for bursts of abnormal electrical activity.
In some people, a tendency to develop absence seizures is inherited. How it is passed on is not clear, but several members of an extended family may have this type of epilepsy. The parents of children with this type of epilepsy may wish to have genetic counselling to see if there is a chance of further children being affected.
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