A seizure (or convulsion) is an abnormal electrical discharge of a brain cell. New seizures may develop following a brain injury or stroke. The most common type of seizure is a motor seizure. If the electrical discharge is in an area of the brain that controls movement, repetitive muscle twitching or thrashing can occur. Motor seizures can range from very tiny movements of one part of the body (called a focal seizure) to thrashing about of the entire body (called a generalized seizure).

Not all seizures will produce movement. The abnormal electrical discharge can occur in areas of the brain outside of the motor control region (area that initiates movement). Patients may have periods where they lose consciousness or "blank out".

The only way to know for certain if a seizure is present is to perform an EEG.

Seizures are treated with medications called "anticonvulsants".