Witnessing a seizure is not something you're likely to forget, but as a bedside nurse it's something you're bound to experience. Seizures are a transient disruption in brain function caused by excessive electrical discharge of cortical neurons in one or more areas of the brain. They affect an estimated 2.5 million Americans. Each year in the United States, 300,000 people-120,000 of them younger than 18-have a seizure for the first time, and about 181,000 people are diagnosed with epilepsy.