Tonic seizures are fairly uncommon. They occur mostly in people with
Lennox-Gastaut syndrome. This is a severe form of generalized
epilepsy that begins in early childhood. (Children
with Lennox-Gastaut syndrome may also have atonic seizures.)
When a tonic seizure occurs, the muscles in the body contract and the entire body stiffens. This occurs suddenly and without warning. And it often causes the person to fall down.
People who have tonic or atonic seizures are likely to be injured
when they fall. Children may have to wear helmets and restrict their activities
to prevent serious injury.