DEAR DR. DONOHUE: Please say something about narcolepsy. For years, I have gone into what my friends call a coma. I cannot be awakened. People tell me they cannot feel my pulse. Then it passes. Is this narcolepsy? I am afraid to tell my doctor about it. – Anon.

ANSWER: Narcolepsy is irresistible sleep attacks during the day and regardless of the situation. Attacks last from a few minutes to as long as half an hour, and they can occur at the most inopportune times, like during a business conference or while driving a car.

The condition usually starts between the ages of 5 and 50.

There are three other signs that often are part of the narcolepsy picture. One is cataplexy. It’s the sudden onset of muscle weakness without loss of consciousness that’s precipitated by an emotional reaction. Responding to a joke with a hearty laugh, for example, can trigger cataplexy. The muscle weakness varies from a transient sagging of the head to a dramatic fall to the floor with muscles temporarily paralyzed.

Another narcolepsy symptom is hallucinations in the moments before falling asleep or upon wakening. People hear or see things that are not present.

Some narcoleptics also suffer from sleep paralysis – a transient inability to move when they first wake in the morning.

Narcolepsy often has genetic roots, and a search of the family tree for other members with it furnishes more evidence for it.

There are medicines that can control it. The newest one is modafinil.

Some of what you said does not fit narcolepsy. The pulse is not lost during an attack. You must mention this to your doctor. You could have a heartbeat abnormality that’s causing these spells and is fixable.

DEAR DR. DONOHUE: My son recently got a rotavirus infection and ended up in the hospital because he was so dehydrated. Please educate other parents about rotavirus. I had to learn about it the hard way. – T.D.

ANSWER: The rotavirus is the major cause of dehydrating diarrhea in children less than 5 years old. It usually strikes in the winter and can spread from child to child easily. Adults can be infected, but they have a relatively mild illness from it.

About two days after the virus enters the body, the youngster develops a moderate fever. Then diarrhea starts. It is profuse, watery and frequent, and lasts five to seven days. Vomiting can occur.

It’s impossible to distinguish a rotavirus infection without lab confirmation, but any diarrhea of great severity that dehydrates a child is suspicious for rotavirus. Hydration is the only treatment. If this cannot be accomplished at home, then hospitalization is necessary for intravenous fluid hydration.

DEAR DR. DONOHUE: What can you tell me about the spleen? I read that it is the most ignored and misunderstood of all organs. I am in constant pain in the spleen area. An ultrasound showed it to be enlarged. Now I am scheduled for a CT scan. – M.J.

ANSWER: The spleen is on the upper, far-left side of the abdomen, next to the stomach and partially between the stomach and the diaphragm muscle – the horizontal muscle that separates chest from abdomen.

The spleen filters germs and other foreign material from the blood. It makes antibodies. These two functions make it an important part of the immune defense system. The spleen also removes worn-out red blood cells from the circulation and recycles their parts for the production of new red blood cells.

An enlarged spleen creates pain and a heavy, dragging sensation in the upper left side of the abdomen.

Splenic problems are many, and the causes for splenic enlargement are equally many. Some anemias, for example, enlarge the spleen. I don’t want to list for you all of the causes of an enlarged spleen. Such a list would only serve to unsettle you, and there might be no good reason to do that. Innocent conditions also enlarge the spleen.

The CT scan can help clear the air about the nature of your spleen’s enlargement.

DEAR DR. DONOHUE: What’s a biopsy? What does it do to a patient? How long does it take to do one? Are there any risks? Must a patient go under anesthesia? – J.T.

ANSWER: A biopsy is a small sliver of tissue taken for microscopic examination. The microscope can provide answers to questions that can’t be settled with any other test.

Most biopsies are done quickly and relatively painlessly. Sometimes a fine needle can obtain the specimen. Sometimes a scalpel is used, and often the only anesthesia necessary is local anesthesia – i.e., numbing the skin and the involved tissues.

There are risks involved in any procedure. There are risks involved in taking a pill. The risks from a biopsy, however, are usually quite small, and most often there are no complications from having one done.

To answer your question fully, I need to know what is being biopsied.