Transcript: Several conditions can result in loss of consciousness, yet not be associated with the abnormal electrical discharge in the brain characteristic of a seizure. When a person suddenly loses consciousness, it can be a tense and frightening moment! If an observer reports that a person is stiffening, shaking or jerking during the period of unconsciousness—or if an experienced medical history taker notes symptoms of epilepsy—then the event can be categorized as a seizure. Often, however, this period of unconsciousness goes unobserved, or the symptoms during the event are unclear. It is important to understand that there are other conditions that can cause sudden loss of consciousness! The most common medical cause of loss of consciousness is fainting, for which the medical term is syncope. Fainting happens when the brain does not get enough blood flow. You can blame the “fight-or-flight” response for this occurrence! When the brain experiences a sudden stress, blood rushes to the muscles in anticipation of fleeing or counterattacking a danger. The contraction of the muscles during the fight or flight that follows returns blood to the heart and brain.  But in modern society, we may not react to certain kinds of perceived danger or pain, like the drawing of blood for laboratory tests.  In cases like this, blood pools in the muscles, and the lack of muscle contraction may prevent the heart from having enough blood to pump to the brain. This can cause the brain to temporarily shut down, resulting in vasovagal syncope, the medical term for a common faint.  Fainting can also can happen when people have lost blood, are dehydrated, or have certain cardiac problems. Fainting from heart problems can be serious, and requires immediate medical investigation. Usually when people faint, they lie limp. However, some faints provoke a true seizure, which is one way the brain may react to reduced blood supply. A seizure with fainting, which is called convulsive syncope, does not imply epilepsy…but it does require that medical professionals look into what is causing the fainting. In other cases, loss of consciousness can stem from a loss of one of the brain’s two vital “fuels”: sugar and oxygen.  Excessively low sugar is called hypoglycemia, and can definitely cause loss of consciousness. Low sugar can result from prolonged fasting, excess insulin hormone, medication side effects, or a reaction to a high carbohydrate load. People with hypoglycemia usually feel a buildup of hunger, lightheadedness, and a general ill feeling before losing consciousness. While hypoglycemia can cause symptoms, like loss of consciousness, that imitate seizures, it can also provoke real seizures. Low oxygen, which can result from lung disease, choking, or high altitude, can also cause symptoms that imitate a seizure, or provoke a real one. Another common reason for loss of consciousness is a condition called transient ischemic attack, or TIA. In a TIA, blood flow to a piece of the brain is interrupted briefly, causing brain tissue to temporarily stop working Some parts of the brain—like the brainstem—are critical for the maintenance of consciousness. When a TIA affects this area, consciousness may suddenly be lost.  Because loss of consciousness can be caused by several different conditions, many people who are having seizures mistakenly think they are experiencing something else. On the other side of the coin are people who think they have seizures, but actually have one of the imitators. In the end, if seizures do not respond to the usual treatments, then the diagnosis should be reconsidered.+