Absence Seizure

Alternate Names
petit mal seizure

Definition of Absence Seizure

Seizures are caused by sudden, abnormal discharges of electrical impulses from brain cells. Absence (pronounced "ab-SONTS", a French word meaning "not present") seizures are a type of seizure that occur almost exclusively in children after the age of 4 but before puberty, causing brief periods of decreased awareness.

What is going on in the body?

Neurons are the nerve cells within the brain. They coordinate movement, thinking, personality, and sensory activities. Neurons communicate with each other through electrical discharges.

A seizure occurs when excitable neurons give off abnormal electrical discharges. There are different types of seizures, depending on where the excitable neurons are located. Epilepsy or seizure disorder is diagnosed when an individual has a multiple seizures over a span of time.

Seizures are divided into two main types: generalized and partial. Generalized seizures result from abnormal electrical discharges that affect the entire brain. The person loses consciousness or awareness of the environment. Partial seizures are the result of an abnormal electrical discharge starting and affecting only one part of the brain but may spread to involve the entire brain (known as partial seizure with secondary generalization). Absence seizures are a generalized type of seizure.

What are the signs and symptoms of the condition?

Absence seizures typically cause brief losses of awareness usually lasting less than a minute, though sometimes they can last from minutes to hours. These episodes may be interpreted by a child's parents and teachers as periods of daydreaming or not paying attention. They often go unnoticed by the child.

They may occur several hundred times a day. Unlike with many types of seizures, falls and abnormal movements may not occur. The spells may be so brief as to allow the child to walk, run, or even ride a bicycle without incident. However, small movements of the eyes, face, or fumbling movements of the fingers and hands may be seen during the seizure.

What are the causes and risks of the condition?

Absence seizure disorder is a genetic disorder, meaning that it is causes by a defect in the DNA. Many individuals with absence seizure disorder have a family member with epilepsy; however, no clear pattern of inheritance has been established.

What can be done to prevent the condition?

The disorder cannot be prevented.

How is the condition diagnosed?

Diagnosis of epilepsy begins with a medical history and physical exam. An electroencephalogram (EEG) will be ordered. An EEG measures electrical activity within the brain. If a seizure occurs during the EEG, the abnormal activity can be detected. A normal EEG does not rule out seizures, simply because it may have been taken at a time when seizure activity was not occurring.

Other tests that may be ordered include:

• blood tests to look for diseases or conditions causing the seizures
• cranial CT scan to look for abnormalities in the brain
• cranial MRI to provide a closer look at brain structures
• positron emission tomography, or PET scans, to identify the abnormal brain area

What are the long-term effects of the condition?

Many individuals outgrow this type of seizure, never to have another seizure; however, many times these types of seizures are simply replaced by other types of generalized seizures in adulthood.

What are the risks to others?

Absence seizures are not contagious and pose no risk to others.

What are the treatments for the condition?

Medicines used to treat epilepsy are known as anticonvulsants. Common anticonvulsants used for absence seizures include:

• ethosuxamide
• lamotrigine
• topiramate
• valproate sodium

A person with epilepsy may be embarrassed or depressed. Counseling about the condition may help the individual and the family. Support groups exist for those with epilepsy.

Certain aniconvulsants can worsen absence seizures. These drugs include:

• carbemazepine
• tiagabine
• vigabatrin

What are the side effects of the treatments?

Medicines used to treat epilepsy may cause drowsiness and allergic reactions.

What happens after treatment for the condition?

Many substances interfere with the action of anticonvulsants. These include over-the-counter medicines, other prescription medicines, and herbal remedies. Individuals with seizures should consult their healthcare professionals before taking any new products. If seizures are well-controlled, the individual may live a normal life. However, some people may have significant disabilities from their epilepsy.

How is the condition monitored?

Blood is tested regularly to monitor the levels of anticonvulsants. Any new or worsening symptoms should be reported to the healthcare professional.