There are several reasons why a person could lose consciousness rapidly. Perhaps the most important distinction is whether you had syncope or a seizure because the causes and treatments are different for these two conditions. There are several details in the medical histories that are generally helpful. A seizure more typically is associated with auras (unusual sensations, such as smelling a particular odor or feeling tingling over a body part) before the loss of consciousness, vigorous involuntary movement of the limbs, passing of urine and/or feces, clenching teeth, and possibly tongue biting. In addition patients often feel disoriented upon awaking after a seizure. In contrast to the typical seizure, syncope may or may not be associated with symptoms before consciousness is lost. Sometimes, patients may feel lightheaded, sweaty, nauseated, or notice visual changes. Although syncope is associated with loss of posture, it is less common to see involuntary limb movements, tongue biting, or incontinence of urine or stool.
Despite the above clues, it can still be quite difficult to determine whether you had a fainting episode or a seizure. Sometimes I can find clues during a physical examination or basic laboratory testing. But even after extensive testing, it can be hard to categorize some cases as syncope or seizure.
