A petit mal seizure is a temporary disturbance of brain function caused by abnormal electrical activity in the brain and characterized by abrupt, short-term lack of conscious activity ("absence") or other abnormal change in behavior.

Petit mal seizures occur most commonly in people under age 20, usually in children ages 6 to 12. They may occur in combination with other types of seizures.

Typical petit mal seizures last only a few seconds, with full recovery occurring rapidly and no lingering confusion. Such seizures usually manifest themselves as staring episodes or "absence spells" during which the child's activity or speech ceases.

The child may stop talking in mid-sentence or cease walking. One to several seconds later, speech or activity resume. If standing or walking, a child seldom falls during one of these episodes.

"Spells" can be infrequent or very frequent, occurring many times per hour. Up to hundreds of seizures can occur in a single day. They may occur for weeks to months before they are noticed. They can interfere with school function and learning. Teachers may interpret these seizures as lack of attention or other misbehavior.

Atypical petit mal seizures begin slower, last longer, and may have more noticeable muscle activity than typical petit mal seizures. There is usually no memory of the seizure.

No cause can usually be found for typical petit mal seizures. No neurologic or other disorders are usually discovered. Atypical seizures may or may not be associated with other neurologic disorders.

Causes may be unidentifiable, or identified as congenital brain abnormalities, complications of kidney or liver disease, or brain injuries from trauma or birth complications. Sometimes, a family history of seizures indicates a hereditary type of seizures.

TYPICAL

• Muscle activity changes
  • No movement
  • Hand fumbling
  • Fluttering eyelids
  • Lip smacking
  • Chewing
• Consciousness changes
  • Staring episodes (unintentional)
  • Lack of awareness of surroundings
  • Sudden halt in conscious activity (movement, talking, etc.)
  • May be provoked by hyperventilation or flashing lights, in some cases
  • Abrupt beginning of seizure
  • Each seizure lasts no more than a few seconds
  • Full recovery of consciousness, no confusion
• No memory of seizure

• Atonic seizure
  • No muscle movement
  • Slumping, loss of posture
  • Loss of muscle tone
  • Falling down
• Consciousness changes
  • Unintentional staring
  • Lack of awareness of surroundings
  • Sudden stop of conscious activity (movement, talking, etc.)
  • Hand fumbling
  • Fluttering eyelids
  • May be provoked by hyperventilation, in some cases
  • May have slower, gradual beginning of seizure
  • Each lasts only seconds to minutes
  • Recovery may be slower
  • May have short period of confusion or bizarre behavior
• No memory of seizure

The physical examination is usually normal, although some neurologic abnormalities may be present in some patients.

Transmission of information from nerve cell to nerve cell occurs by an electrochemical process that can be detected as electrical activity by an electroencephalograph (EEG). A single or multiple EEG exams may be necessary to show changes typical of petit mal seizures. Occasionally, a patient may need to have EEG monitoring from 1 to several days to detect these EEG changes.

Various laboratory tests, a head CT scan, or a head MRI may be used to rule out specific causes of the seizures.