Seizure is defined as:

• A. A sudden attack of illness, especially a stroke or epileptic fit.
• B. A chronic mood disorder.
• C. A fainting spell caused by dehydration.
• D. A mild headache.

Answer: (A)

A seizure is a sudden disruption of normal brain function caused by abnormal electrical activity in the brain, which can manifest as convulsions, altered awareness, or other abrupt symptoms. The description of a seizure as a sudden attack of illness best fits this idea because it emphasizes the abrupt onset of a neurologic event. The other descriptions refer to conditions that are not about a rapid brain disturbance: a chronic mood disorder involves long-term changes in mood; a fainting spell from dehydration describes transient loss of consciousness due to reduced blood flow; and a mild headache is a minor, nonspecific symptom not due to sudden brain electrical upheaval.