Dear Doctor: Just how risky are sinus infections? I read about a teenager who died recently after a sinus infection spread to his brain. Is this common? How do you prevent a sinus infection?

Dear Reader: We hadn't heard about this before we received your letter, but we did a search and found the incident you're referring to.

A 13-year-old boy in Michigan who had been diagnosed with a sinus infection went on to develop migrainelike headaches. The severe headaches worsened over the course of several weeks and an MRI was performed. It was discovered that a viral infection had spread to his brain and caused blood clots, which led to a series of strokes, according to his family members. Despite emergency surgery, the boy passed away. It's a tragic story and, considering that sinus infections are common -- an estimated 31 million are diagnosed in the United States every year -- it's an alarming one. However, the fact is that these types of complications are rare.

The sinuses are pairs of air-filled cavities located behind the lower forehead, behind the nose, on either side of the bridge of the nose, and within the bony structures of the cheeks. In a heathy sinus, a thin layer of mucus catches dust, dirt or debris and, with the aid of tiny hairlike structures, clears it away. That mucus then drains into the nasal passage and winds up in the nasopharynx, which is where the very back of the nose and the throat converge. At that point, the mucus continues its journey down the esophagus and into the stomach.

A sinus infection occurs when a virus, bacterium or fungus causes the tissues that line these cavities to become inflamed. When this happens, the flow of mucus is blocked and it begins to collect in the sinus cavity. This can cause symptoms like congestion, postnasal drip, excess and sometimes discolored (usually greenish) mucus, tooth pain, a feeling of pressure, frontal headache, fatigue and even bad breath. In rare cases, the pathogens causing a sinus infection can cross the blood brain barrier, which is a filtering mechanism that protects brain tissues, and cause an abscess.

Conditions with similar symptoms, like colds or allergies, can be mistaken for a sinus infection. An accurate diagnosis requires an examination of the throat, nose and sinuses. This can include a physical examination with an endoscope, X-rays or a CT scan, and a mucus culture to pinpoint the cause of infection. Antibiotics may be used when the infection is bacterial but will not help with a viral infection. Symptoms can be eased with over-the-counter antihistamines, nasal decongestant sprays and nasal saline washes. Patients are often counseled to drink plenty of fluids to help thin the mucus.

Prevention consists of the same steps you take to avoid catching a cold or the flu. The Centers for Disease Control and Prevention suggest:

-- Practice good hand hygiene.

-- Keep the family up-to-date with immunizations.

-- Steer clear of individuals with upper respiratory infections.

-- Avoid exposure to tobacco smoke.

-- Use a humidifier -- and be sure to keep it clean.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I understand that poking cotton swabs into the ear is dangerous. But how is one supposed to clean the ears otherwise? I don't want to see goopy yellow wax in anyone's ear canal or to have it in my own.

Dear Reader: This is a very good question -- and one that poses another question: Why clean your ears?

Let's assess the potential health benefits (or lack thereof) of doing so. This so-called wax, called cerumen, is a necessary product for the ear canal. Produced by glands under the skin, cerumen is composed of many different chemicals that mix with the skin cells that slough off within the ear canal. Cerumen moistens, cleans and lubricates the ear canal. It also acts as a barrier to dust, water and particles from the outside world. Further, cerumen creates an acidic environment within the ear canal that works against invading bacteria, even as its antibacterial enzymes and antibodies further protect the ear from bacteria.

I know that it may be unsightly and seem unhygienic to have yellowish material coming out of the ear, but letting cerumen come out on its own is actually the more hygienic course. First, removing the cerumen dries out the canal, which can lead to skin irritation within the canal. Often, this causes the ear canal to feel itchy, leading to more use of cotton swabs and even greater irritation of the canal. Second, the cotton swabs can make cerumen itself drier, reducing its ability to come out on its own. Swabs also can push wax further into the canal toward the eardrum.

In some instances, the tips of the cotton swabs or the cotton fibers themselves can dislodge and remain within the ear canal. The fibers then can mix with the cerumen, leading to closure of the ear canal and loss of hearing. Finally, putting a cotton swab in the ear canal can perforate the eardrum.

In short: Cotton swabs should not be used within the ear.

Nonetheless, the belief that the ear canals should be cleaned is widespread. Two surveys have found that 90 percent of people think that they should clean their ear canals, with many people cleaning their ears on a regular basis. This practice appears to be passed from parents to their children as a part of normal hygiene.

That said, even without the use of cotton swabs, cerumen can harden and remain lodged within the ear canal. This is especially likely to occur in people with ear infections, psoriasis or eczema, or in those who use hearing aids, ear plugs or ear phones. In such cases, ear drops can help soften the wax, so that it comes out on its own. Irrigating the canal with water -- at home or within a doctor's office -- can provide additional relief. If such hardening is a recurrent problem, the answer is to more regularly use ear drops.

To sum it up, cerumen (ear wax) is necessary to lubricate and protect the ear canal from infection. Cotton swabs can be used to clean the outer ear, but -- please -- don't put them inside the ear.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My doctor says I'm on the verge of being diagnosed with something called "metabolic syndrome." Is it serious? Can I get rid of it?

Dear Reader: Metabolic syndrome refers to a collection of largely preventable conditions that add up to a serious health threat. As family doctors, the "preventable" part of that sentence is at the core of our work, which means you've hit on a topic near and dear to our hearts. Our mission, as we work with our patients over the years, is to track the big picture of an individual's health. When it comes to metabolic syndrome, it's not a pretty one.

Individuals who have high blood pressure, elevated levels of cholesterol and triglycerides, abnormal blood sugar, and who carry excess fat in the abdomen and around the waist are considered to have metabolic syndrome. When these conditions are all present at the same time, they lead to an increased likelihood of developing diabetes and heart disease, and an increased risk of heart attack and stroke.

Researchers who analyzed data collected by the Centers for Disease Control and Prevention between 2003 and 2012 found that up to 35 percent of adults in the United States meet the diagnostic criteria of metabolic syndrome. When sorting by age, it turned out that almost half of all people over the age of 60 have metabolic syndrome. (By contrast, slightly fewer than 20 percent of adults between the ages of 20 and 39 qualify for the diagnosis.) That's because we slow down as we age, both physically and metabolically.

And while being overweight or obese, inactive and insulin resistant are primary causes of metabolic syndrome, the researchers found that race, age and ethnicity play a role as well. For reasons that are not yet fully understood, the condition is more prevalent among Asians, African-Americans, Native Americans and Hispanics, who have the highest rate of metabolic syndrome of all ethnic groups.

The good news is that metabolic syndrome is preventable. The even better news for the tens of millions of Americans now entering their senior years is that it's also reversible. The challenge is that it's as much about lifestyle changes as it is about medication. Yes, there are effective drugs to address issues of blood pressure and high cholesterol. But the addition of regular exercise to daily life, as well as wide-ranging dietary changes are also necessary.

-- Change your diet: Say goodbye to refined and processed foods. Cut as much sugar from your diet as possible. Start getting your calories from lean proteins, whole grains and legumes, nuts, healthful fats, fresh vegetables and fruits, and plenty of leafy greens. A moderate drop in body weight, even just 5 or 10 percent, can have an effect on the body's ability to recognize and respond to insulin.

-- Get moving: Walk instead of drive. Choose stairs over the elevator. Join a walking group. Start biking. Go for a swim. Start lifting weights. By choosing activities you enjoy and have done in the past, you'll have a better shot at sticking with it. And start small. Set goals that are realistic, manageable and sustainable.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)