Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Absence Seizures (Petit Mal Seizures)

Diagnosis

The doctor will ask you to describe your child's symptoms, including how often the symptoms occur and how long they last. The doctor will review your child's medical history, especially any history of birth trauma, serious head injury or infections involving the brain, such as encephalitis or meningitis. The doctor also will ask whether any other members of your family have had similar symptoms or have received treatment for any type of epilepsy.

The doctor will do a thorough physical, including a complete neurologic examination of your child. This examination may be followed by routine blood tests to check for common medical illnesses that either can mimic epilepsy or trigger seizures. In most cases, the results of your child's physical examination and blood tests will be normal.

As a final step in the diagnostic process, your doctor may order an electroencephalogram (EEG). An EEG is a painless test that detects the electrical activity in your child's brain and translates it into a series of printed patterns. In many children with absence epilepsy, the EEG shows a specific combination of spike and wave patterns that confirms the diagnosis. In some cases, the doctor also may order a magnetic resonance imaging (MRI) test or a computed tomography (CT) scan of your child's brain to look for a tumor or other abnormality that may be causing the absence seizures. This may be done if your child has one or more of the following problems: prolonged seizures; an unusual pattern of symptoms or abnormal findings on the physical or neurological examination; or if he or she has had a condition, such as birth trauma, head injury, encephalitis or meningitis, that would put him or her at higher risk of seizures.