DEAR DR. DONOHUE: A CT brain scan revealed a subdural hematoma in the right frontal and parietal areas. I had surgery to drain the blood. A follow-up brain scan is clear. I am 90 years old. Will you explain this ailment and the procedure to eliminate it? – R.T.

ANSWER: A hematoma is a pool of blood that has congealed. It’s like a large blood clot. “Subdural” gives its location. It’s beneath the dura, the outermost and toughest of the brain’s covering tissues. “Frontal” and “parietal” refer to the forward and side parts of the brain.

Older people are often victims of subdural hematomas. With age, the brain shrinks a bit. Veins that bridge the empty space beneath the dura are subject to tearing and bleeding. Head trauma is the cause. “Trauma” can give the wrong impression since the incident can be so slight that a person has no recollection of anything happening. It can also be more dramatic, as in a strike to the head from a fall to the ground or other direct blow to the head.

Quite frequently, a subdural hematoma is present for some time before it is actually diagnosed. When it is large and presses on the brain, people might complain of a headache, weakness of an arm or leg, trouble staying balanced or difficulty walking. Sometimes people’s thinking declines, and they find it hard to express their thoughts. When these symptoms arise, people usually see their doctor. Brain scans reveal the hematoma.

To drain the collection of blood, a neurosurgeon makes a small hole in the skull and evacuates the congealed clot. When the hematoma is removed and pressure on the brain is relieved, symptoms go away.

Subdural hematomas also happen at younger ages. They behave differently from how they do at older ages.

DEAR DR. DONOHUE: My 20-year-old nephew recently left for basic training. A week after he started training, something went wrong with his muscles. The diagnosis was rhabdomyolysis, and he was discharged. I can’t find any information on it other than it being a possible side effect of Lipitor. Can you tell me what it is and what the prognosis is? – L.K.

ANSWER: The name is strange and public recognition of it is close to nil, but rhabdomyolysis (RAB-doe-my-AWL-uh-siss) is not rare. It’s muscle destruction so great that muscle cells’ internal components are released into the blood. Potassium and myoglobin are among those components.

High levels of potassium can trigger such abnormal heartbeats that heart pumping is affected. High blood levels of myoglobin can shut down the kidneys.

People with rhabdomyolysis complain of great muscle pain and muscle weakness. Often their urine turns the color of Coke.

Heat stroke, large amounts of alcohol and crush injuries cause it. So can excessive exercise. It is a hazard for military recruits and police and firemen in training. Statin drugs like Lipitor can cause it, but rarely do.

Quick action prevents permanent kidney damage. The prognosis for treated and recovered patients is usually quite good.

DEAR DR. DONOHUE: My son is 15, and in the past 10 years, he has had at least four outbreaks of poison ivy every year – winter, spring, summer or fall. One year during winter break, the poor kid never left the house but still came down with poison ivy. His older brother walked by some weeds and must have contacted it and it rubbed off on his brother.

Many times he gets it so bad that he can barely move. A couple of times, the doctor gave him prednisone because it was so bad. Is there anything that can be done for him? – P.O.

ANSWER: Poison-ivy rash occurs when the sap of the poison-ivy plant gets on the skin. The outbreak of blisters that follows usually occurs in a line. The lines can be all over the body if the sap has gotten all over the body. In northern climates, like yours, winter poison ivy is unusual.

Your son’s story is quite exceptional. It has me wondering if his outbreaks are really poison ivy. The next time he breaks out in this rash, get him to a dermatologist immediately. There are many illnesses that produce a similar kind of rash.

DEAR DR. DONOHUE: How is West Nile fever spread? My sister says she has seen in the paper and on TV that it can be spread from person to person. Is that true? – W.R.

ANSWER: Mosquitoes are responsible for the spread of West Nile fever. At one time, blood transfusion spread it to a few, but that danger has been removed with the testing of all donated blood for the virus. Rarely, transplanted organs have been the source of infection. Pregnant women can pass the virus to the fetus. It is not spread from person to person in any other manner.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.