Absence seizure

  • Definition
    • 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.

  • Alternative Names
    • Seizure - petit mal; Seizure - absence; Petit mal seizure; Epilepsy - absence seizure

  • Causes
    • Absence seizures occur most often in people under age 20, usually in children ages 6 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 occur with other types of seizures, such as generalized tonic-clonic seizures (grand mal seizures), twitches or jerks (myoclonus), or sudden loss of muscle strength (atonic seizures).

  • 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 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
    • Treatment for absence seizures includes medicines, changes in lifestyle for adults and children, such as activity and diet, and sometimes surgery. Your doctor can tell you more about these options.

  • References
    • Abou-Khalil BW, Gallagher MJ, Macdonald RL. Epilepsies. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SK, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 101.

      Marcdante KJ, Kliegman RM. Seizures (paroxysmal disorders). In: Marcdante KJ, Kliegman RM, eds. Nelson Essentials of Pediatrics. 7th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 181.

      Wiebe S. The epilepsies. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 403.