Absence seizure
Seizure - petit mal; Seizure - absence; Petit mal seizure; Epilepsy - absence seizure; Non-motor generalized seizure
An absence seizure is the term for a type of seizure involving staring spells. This type of seizure is a brief (usually less than 15 seconds) disturbance of brain function due to abnormal electrical activity in the brain.
The major areas of the brain have one or more specific functions.
Causes
Seizures result from overactivity in the brain. Absence seizures occur most often in people under age 20, usually in children ages 4 to 12.
In some cases, the seizures are triggered by flashing lights or when the person breathes faster and more deeply than usual (hyperventilates).
They may also occur with other types of seizures, such as bilateral tonic-clonic seizures (grand mal seizures), twitches or jerks (myoclonus), or sudden loss of muscle strength (atonic seizures).
Having a brain seizure can be a terrifying experience. If you have a seizure more than once, you may have epilepsy, a problem with electrical activity in your brain. So, what causes epilepsy? For most people, the brain sends electrical signals throughout the body efficiently, in a coordinated way. In epilepsy, however, the normal pattern of electrical activity becomes disturbed. This causes the brain to be too excitable, or jumpy, and it sends out abnormal signals. The result is repeated seizures that can happen at any time. Epilepsy seizures usually begin between ages 5 and 20, but they can happen at any age. Common causes include Stroke, or a mini-stroke called transient ischemic attack; Dementia, or loss of brain function, such as Alzheimer's disease; Traumatic brain injury; Infections in the brain; Brain problems you are born with; or perhaps, a Brain tumor. Some people with epilepsy may have simple staring spells, while others have violent, uncontrollable shaking and loss of consciousness. Before each seizure, some people may have strange sensations, such as tingling, smelling an odor that isn't really there, or emotional changes. This is called an aura. Your doctor will perform a number of tests to find out if epilepsy is causing your seizures. One test, an electroencephalogram or EEG, checks your brain's electrical activity. Other tests can take detailed pictures of the part of your brain that is causing your seizures. Your doctor will most likely start treating your epilepsy with medication. These medicines, called anticonvulsants, may reduce the number of seizures you have in the future. Sometimes, changing the diet of a child with epilepsy can help prevent seizures. Your doctor will probably talk to you about making some changes in your life, such as reducing your stress, getting more sleep, and avoiding alcohol and recreational drugs. Surgery to remove a brain tumor or abnormal blood vessels or brain cells may make the seizures stop. Another surgery can place a Vagus nerve stimulator in your brain. This device is like a pacemaker for your brain that limits the number of seizures you have. For many people, epilepsy is a lifelong problem, and they'll always need to take anti-seizure medicines. There is a very low risk of sudden death with epilepsy. However, you, or someone else, can be seriously injured if you have a seizure while driving or operating equipment. If your seizures are uncontrolled, you should not drive.
Symptoms
Most absence seizures last only a few seconds. They often involve staring episodes. The episodes may:
- Occur many times a day
- Occur for weeks to months before being noticed
- Interfere with school and learning
- Be mistaken for lack of attention, daydreaming or other misbehavior
Unexplained difficulties in school and learning difficulties may be the first sign of absence seizures.
During the seizure, the person may:
- Stop walking and start again a few seconds later
- Stop talking in mid-sentence and start again a few seconds later
The person usually does not fall during the seizure.
Right after the seizure, the person is usually:
- Wide awake
- Thinking clearly
- Unaware of the seizure
Specific symptoms of typical absence seizures may include:
- Changes in muscle activity, such as no movement, hand fumbling, fluttering eyelids, lip smacking, chewing
- Changes in alertness (consciousness), such as staring episodes, lack of awareness of surroundings, sudden halt in movement, talking, and other awake activities
Some absence seizures begin slower and last longer. These are called atypical absence seizures. Symptoms are similar to regular absence seizures, but muscle activity changes may be more noticeable.
Exams and Tests
The doctor will perform a physical exam. This will include a detailed look at the brain and nervous system.
An EEG (electroencephalogram) will be done to check the electrical activity in the brain. People with seizures often have abnormal electrical activity seen on this test. In some cases, the test shows the area in the brain where the seizures start. The brain may appear normal after a seizure or between seizures.
Blood and urine tests may also be ordered to check for other health problems that may be causing the seizures.
Head CT or MRI scan may be done to find the cause and location of the problem in the brain.
Treatment
References
Abou-Khalil BW, Gallagher MJ, Macdonald RL. Epilepsies. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff’s Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 100.
Kanner AM, Ashman E, Gloss D, et al. Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs I: Treatment of new-onset epilepsy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the American Epilepsy Society. Neurology. 2018;91(2):74-81. PMID: 29898971
Marcdante KJ, Kliegman RM. Seizures. In: Marcdante KJ, Kliegman RM, Schuh AM, eds. Nelson Essentials of Pediatrics. 9th ed. Philadelphia, PA: Elsevier; 2023:chap 181.
Wiebe S. The epilepsies. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 375.
Version Info
Last reviewed on: 1/23/2022
Reviewed by: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School at Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
