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Having Trouble with Your Sense of Smell

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If you or a loved one is not eating well and losing weight, there could be a number of causes. One often overlooked possibility—a smell and taste disorder. Surprisingly common but little known, this is a condition in which a person’s sense of smell, taste or both are either lost or so distorted that most foods taste terrible and most smells are noxious.

As many as 14 million Americans over age 55 are affected by some degree of smell loss or distortion of smell or taste. Half of people age 65 or older are no longer able to fully detect odor and taste, and in those over 80, the figure is 75%.

People who suffer from dysosmia experience a distorted sense of smell that usually is unpleasant.

With dysgeusia, a distorted sense of taste, sufferers experience abnormal taste sensations, usually unpleasant, that can be triggered by any food that is consumed.

My story: Sixteen years ago, after catching a bad cold, I experienced a smell disorder. The cold wasn’t serious, but after it cleared up, I realized that my sense of smell was very poor and my sense of taste was mildly impaired.

One morning, I sniffed some milk to check its freshness, and although the carton was well past its sell-by date, the milk didn’t smell sour to me. Later, while cleaning the dog pen, I realized that the dog’s stool smelled surprisingly pleasant. I knew something was amiss! As a neurologist, I was intrigued by my condition and began intensively studying smell and taste disorders.

My research led me to several experts in the field. And as a result of my research, I eventually opened my own center, the Taste & Smell Disorders Clinic, as part of my neurology practice in Austin, Texas.

IDENTIFYING THE CULPRIT

The type of smell loss that I experienced is actually quite common. Nasal and upper-respiratory viral infections cause about 25% of cases of acute impaired smell.

Other causes of smell and taste disorders…

Aging is the most common cause of gradual decline in one’s sense of smell and taste. The age-related decline in our ability to smell and taste can be due to several factors that normally occur as we grow older. These include a loss of smell-detecting olfactory nerve cells… a narrowing of the bony opening through which these nerve cells enter the skull… and a reduction of blood flow to the olfactory bulb in the front of the brain, which identifies odors and recognizes flavors.

Viruses (including colds) and allergies may cause cumulative damage to the nasal passages and sinuses, which also may interfere with our ability to smell. Nearly two-thirds of people who have smell loss due to a viral infection develop dysosmia.

Head and nose injuries may damage nerve receptors that travel through the bones of the upper nose and front of the skull.

Certain medications, such as anti­hista­mines… cold remedies… anti­biotics… cholesterol-lowering statins… antidepressants… diuretics… and blood pressure drugs, may interfere with smell and are among the most common causes of taste loss.

Exposure to pesticides and other toxins may cause inflammation that damages nerve receptors involved in smelling.

Smoking damages the mucous membrane lining the inside of the nose.

Excessive alcohol intake may affect regions of the brain involved in smelling.

Neurologic disorders (such as Alzheimer’s disease) damage nerve cells in the olfactory system.

Low levels of vitamin B-12, zinc or thyroid hormone can each interfere with the smell and taste process.

If you are suffering from a loss or distortion of smell or taste, it’s wise to consult an ear, nose and throat doctor or a neurologist. You will be asked several questions, including whether any of the possible causes described above apply to you. An endoscopy, CT scan and/or MRI also may be ordered to help identify the cause of your problem.

DANGERS MAY GO UNRECOGNIZED

Smell and taste disorders can severely affect a person’s quality of life, especially social interactions. Since meals are no longer enjoyable, dining with family and friends loses much of its attraction.

With dysosmia and dysgeusia, eating becomes so unpleasant that it can lead to dangerous weight loss and, in severe cases, malnourishment. Depression is also common among these patients.

The inability to taste or smell properly also can be dangerous, as sufferers may inadvertently eat, say, spoiled meat or not detect the smell of leaking gas.

HOW TO COPE

Because the majority of smell and taste disorders are due to age-related damage of the smell or taste receptors in the nose and/or mouth and the nerve pathways, there is no specific treatment for these types of problems with smelling.

However, if your smell loss is due to a vitamin B-12 or zinc deficiency or low thyroid levels, treating these conditions should help.

If smell loss is due to an ailment such as a cold, improvement usually occurs over time—anywhere from six months to three to four years. In my case, my sense of smell improved 75% in the eight to 10 years after my viral infection was treated.

Interesting finding: When the University of Pennsylvania did a 20-year follow-up study of individuals with various types of smell impairment, many of them continued to improve over 10 to 20 years.

If your smell or taste disorder is caused by medication, simply switching to a different prescription may be the answer.

Caroline, a patient of mine who developed smell and taste loss while taking topiramate (Topamax) to prevent migraines and diltiazem (Cardizem) for mild hypertension, was back to normal three months after switching to propranolol (Inderal), which treats both conditions.

For people who have dysosmia, it often helps to use one to one and one-half teaspoons (three to four times daily) of normal saline and squirt it into each nostril with a small syringe. Do this while in the head-down position so that the saline forms a film of fluid over the nerve cells that identify odors and different flavors. This helps prevent outside odors from getting to the injured smell system. This approach works for about half of all sufferers.

Also helpful: Off-label use of medications such as the antiseizure medication gabapentin (Neurontin) can block abnormal electrical impulses that occur in dysosmia. Such medication helps decrease or stop dysosmia in about 60% of patients with the disorder.

Removal of the olfactory bulb is often a last ditch effort to remove the bad smells and is very successful. Partial loss of smell will result, but loss of taste does not usually worsen after surgery.

The bad tastes of dysgeusia can be helped by trying Cepacol anesthetic lozenges, Xylocaine gel or lidocaine mouthwash and/or the medication gabapentin.

COOKING TRICKS

Because smell and taste disorders inhibit one’s ability to fully savor and enjoy food, many of my patients with partial smell or taste loss have learned to change the way they prepare meals, emphasizing texture, temperature, tartness and spiciness.

Even if you have a taste impairment due to smell loss, you can still appreciate some basic tastes, textures and temperatures. For example, it helps to…

Add spicy salsa to a baked potato (instead of sour cream, which has no flavor in the smell impaired). Try other spicy condiments, such as horseradish or mustard.

Marinate meats with sweet fruit juices, sweet wine or sweet-and-sour sauce.

Eat tart foods, such as grapefruit and oranges.

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Source: Ronald DeVere, MD, a board-certified neurologist and medical director of the Taste & Smell Disorders Clinic in Austin, Texas. Dr. DeVere is coauthor of Navigating Smell and Taste Disorders (Demos Health). Date: November 1, 2011 Publication: Bottom Line Health
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