- Seizure can also refer to the act of taking hold of property, for this meaning see Seizure (law)
A convulsion or seizure happens when the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term convulsion is sometimes used as a synonym for seizure. However, not all epileptic seizures lead to convulsions, and not all convulsions are caused by epileptic seizures.
A seizure happens when the nerves in a person's brain act strangely. Nerves send information, partly through electrical signals. Usually, nerves in the brain (called neurons) do not fire at the same time. During a seizure, groups of nerves start firing together, too fast. This causes there to be too much disorganized electrical activity in the brain.
Most people think a person with a seizure will shake and twitch. Some will, but there are also other kinds of seizures.