Muscle "tone" is the muscle's normal tension. "Atonic" (a-TON-ik) means "without tone," so in an atonic seizure, muscles suddenly lose strength. The eyelids may droop, the head may nod, and the person may drop things and often falls to the ground. These seizures are also called "drop attacks" or "drop seizures." The person usually remains conscious.
Another name for this type of seizure is "akinetic" (a-kin-ET-ik), which means "without movement."
Who gets them?
Atonic seizures often begin in childhood.
What's the outlook?
They often last into adulthood. Many people with atonic seizures are injured when they fall, so they may choose to use protection such as a helmet.
What else could it be?
Patients who have seizures that cause them to fall when they're standing often have tonic seizures (involving sudden muscle contraction) rather than atonic seizures.
How is the diagnosis made?
Usually descriptions of the seizures by witnesses will suggest the diagnosis. Some EEG monitoring may be performed to confirm it. If the seizures persist, other tests may be used to make sure that changes in the heart rhythm or blood pressure are not causing the patient to fall down.
Topic Editor: Orrin Devinsky, M.D.
