DEAR DR. GOTT: Could you please talk about transient global amnesia? I have never seen this discussed in your column before. Thank you.

DEAR READER: Transient global amnesia (TGA) is a rare event that causes sudden, temporary loss of memory. It is often accompanied by repetitive questioning. It is not associated with the more common causes of amnesia such as stroke.

For a positive diagnosis, the patient must meet a set of criteria. He or she must retain knowledge of personal identity and have normal cognition (naming familiar objects, following simple instructions, etc.); the event must be verified by a witness; there cannot be a history of active epilepsy, a recent head injury or the presence of seizures during the episode; the event cannot last more than 24 hours; testing and examination will not reveal signs of brain damage; and, finally, the patient must experience a gradual return of memory.

Some sufferers may also have a racing heartbeat, cold hands and feet, sweating, trembling, headache, vomiting, nausea, dizziness, chest or neck pain, visual disturbances, flushing or chills, a fear of dying and more.

A typical episode lasts about six hours and does not cause lasting damage. Memory of events that happened during (and occasionally for a few hours prior) typically does not return; however, memory of events that were forgotten before that time is eventually regained.

It is important that anyone who witnesses a person develop sudden extreme memory loss call an ambulance or get the sufferer to a hospital immediately, because it is much more likely that a seizure or stroke caused the amnesia.

In most cases, a trigger can be found. The most common include physical or emotional stress, such as strenuous physical activity, sudden immersion in hot or cold water and acute emotional distress, like that caused by a conflict or bad news. Certain medical procedures may also be the trigger. The exact cause of TGA is unknown, but there does appear to be a link between it and migraines in some patients.

Those at higher risk are those with a history of migraines and those over the age of 50. The condition is temporary and doesn't cause lasting damage, so it does not require treatment. Because the cause is unknown, there is no way to prevent these episodes. Recurrence is uncommon.

Because sudden memory loss is more commonly related to a disorder of the brain, I am sending you a copy of my Health Report "Stroke." Other readers who would like a copy should send a self-addressed stamped No. 10 envelope and a $2 check or money order payable to Newsletter and mailed to Newsletter, P.O. Box 167, Wickliffe, OH 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.

Dr. Peter H. Gott is a retired physician and the author of several books, including "Live Longer, Live Better," "Dr. Gott's No Flour, No Sugar Diet" and "Dr. Gott's No Flour, No Sugar Cookbook," which are available at most bookstores or online. His website is www.AskDrGottMD.com. Copyright 2011, United Feature Syndicate Inc.

DEAR DR. GOTT: A while back, I read an article about skin-tag removal. It mentioned something used on fingernails as a home remedy. Can you please tell me what this is?

DEAR READER: The product you are referring to is nail-hardening polish. For the removal of skin tags, it is applied to the lesion once or twice a day. As the coating builds up, it can be pulled off, removing the tag. The process may take up to a week.

To provide related information, I am sending you a copy of my Health Report "Dr. Gott's Compelling Home Remedies." Other readers who would like a copy should send a self-addressed stamped No. 10 envelope and a $2 check or money order payable to Newsletter and mailed to Newsletter, P.O. Box 167, Wickliffe, OH 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.