A seizure occurs when there is a temporary change in the way the brain sends electrical signals. “Atonic just means that there's a loss of muscle tone. Whereas in a tonic seizure, the muscle tone is greatly increased. “If they're having a focal seizure , just stand in front of them and support them to keep them in their chair. “If a generalized seizure, or seizure with a loss of consciousness, lasts longer than five minutes, it's unlikely to stop on its own,” she said.