When the Nose Doesn't Know

Neurology Now
September/October 2010
Volume 6(5)
p 22–23,27–29

Abstract

A neurologist who shares his patients' loss of smell and taste offers advice on how best to cope with this underappreciated problem.

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In 2000, Moses Abelman was rear-ended by an 18-wheeler on the interstate. The Jaws of Life extracted him from his station wagon. Miraculously, he had broken no bones, but the steering wheel had hit him across the mouth and cracked his gum line, giving him a concussion.

Figure. Once smell and taste are lost, their importance in everyday life—from detecting spoiled food, to warning of a fire, to enjoying a meal—becomes obvious.

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Nearly 10 years later, 90-year-old Abelman, now retired from his real estate business, has only one lasting aftereffect from his brush with death: He can't smell a thing. “A couple of months after the accident, I realized that I couldn't smell anything—perfumes, dirty bathrooms, nothing,” he says. “I smell nothing, and I don't taste much—my sense of taste is limited to sweet, sour, and maybe bitter. That's about it.”

Every year, more than 200,000 people visit a physician for help with smell disorders or related problems, according to the National Institute on Deafness and Other Communication Disorders. Some of them, like Abelman, lose their sense of smell (and often, taste) after a traumatic injury. Others find their smell deteriorating gradually as they age, while still others find that their sense of smell doesn't return to normal after a cold, a viral infection, or a bout with hay fever. (See box, “Common Causes of Smell and Taste Disorders.”)

Most people who seek treatment for smell and taste loss visit a neurologist, or an ear, nose, and throat specialist (ENT), or both. But if these specialists can't diagnose or fully treat the problem, people can now visit several specialized smell and taste clinics across the country—including the one at which Moses Abelman eventually sought treatment, the Taste and Smell Disorder Clinic in Austin, TX.

A DOCTOR AND A PATIENT

Patients who visit the Austin clinic find a physician who not only specializes in their condition but also shares it. In 1995, neurologist Ronald DeVere, M.D., Fellow of the American Academy of Neurology, had recently recovered from a viral infection just like any common cold he'd had over the years. One morning, he poured himself a bowl of cereal, took a big bite—and spit it out. The milk was horribly sour, a smell he'd completely missed when taking a whiff from the carton moments before.

Then came his turn to clean out the dog pen for the family's two greyhounds. “I noticed that it didn't smell so bad. In fact, some of it smelled kind of sweet,” Dr. DeVere recalls. “My wife walked out there with her nose held closed.”

The strange problems continued. “I went to the gas pump to fill the car up and could barely smell it,” he says. “I couldn't smell the Old Spice that I was used to wearing.” He didn't seek treatment at the time, but a few months later, while reading a medical journal, Dr. DeVere learned about a smell and taste disorders clinic at the University of Pennsylvania founded by a pioneer in the field, Richard Doty, Ph.D.

His interest was piqued. As a specialist in memory and cognitive disorders, Dr. DeVere already knew about research into a link between Alzheimer's disease and smell loss (see “What the Nose Knows,” September/October 2007, at bit.ly/bUBLTm ). He decided to visit Dr. Doty's clinic, and was so fascinated that a few years later he founded a smell and taste disorders center of his own.

For the past 12 years, he's treated patients with smell and taste problems who come from all over the country—many of whom for the first time are meeting a doctor who really understands how these impairments can change your life. “I don't think most of us can appreciate smell impairment on a day-to-day basis. I really appreciate the feeling, how unhappy people are, because of my own story,” Dr. DeVere says.

NOTHING TO SNIFF AT

If you ask the average person to rate the importance in his or her life of the senses of hearing, vision, smell, and taste (on a scale of 1 to 10), most people will probably rank vision and hearing around 9 or 10, and smell and taste at around 5. In Dr. DeVere's clinic, patients agree that vision gets a 10 and hearing a 9—but they give smell and taste an 8. Once smell and taste are lost, their importance in everyday life—from detecting spoiled food or realizing when you're wearing too much perfume, to warning of a fire, to enjoying your meal—becomes much more obvious.

Even so, most doctors don't learn much about these underappreciated senses in medical school. “We have twelve cranial nerves that transmit sensation in the face, and the usual neurologist's report says ‘cranial nerves 2–12 intact.' People hardly ever test the first cranial nerve, which is the olfactory nerve,” says Dr. DeVere. “For a long time, it was accepted that if you lost your sense of smell with or without taste, there wasn't much you could do. It was an unstudied situation, and we didn't know much about your prognosis.”

That's beginning to change as a result of groundbreaking research into our sense of smell and into smell and taste disorders. In 2004, the Nobel Prize was awarded for the first time to scientists in this specialized field, Richard Axel, M.D., and Linda Buck, Ph.D. They discovered the genes for the first of many olfactory receptors—specialized cells located high up within the nasal passages that are critical to our detection of odors—and found that they are very diverse. Later discoveries have identified hundreds of different types of olfactory receptors, organized in families and subfamilies, which help to explain how we use our sense of smell to recognize so many different odors and flavors.

TREATMENTS

As we learn more about how our senses of smell and taste work, says Dr. DeVere, more opportunities for treating their impairment may emerge. For example, most of the time, damage to the smell and taste system caused by a head injury cannot be repaired. During the 12 to 15 months following such an accident, function may improve somewhat, but most of these patients never recover completely. “But now, researchers are exploring new approaches to trigger regeneration of the olfactory nerve following injury, such as the use of medication or transplantation to replace damaged olfactory nerve cells,” Dr. DeVere explains.

Current treatments for smell and taste loss depend on the source of the problem—and some causes of impairment are more amenable to treatment than others. For example, loss due to medications often can be remedied simply by changing the prescription. One of Dr. DeVere's patients, a woman in her 40s, found her sense of taste impaired after her doctor switched her to a new migraine medication, topiramate. That drug has been found to cause taste problems when used in conjunction with diltiazem, which the woman was also taking for mild hypertension.

Fortunately, an alternative medication, propanalol, was available that could both lower the patient's blood pressure and help with her migraines. Dr. DeVere worked with her family doctor and neurologist to make the switch gradually. Over the next three months, the woman's sense of taste gradually returned to normal.

In other cases, the sense of smell and/or taste never fully recovers. Dr. DeVere says that he has only regained about 50 percent of the smell perception he had prior to his viral infection in 1995. “If there's a dead skunk on the highway, I can smell that there's something there, but it's not that strong,” he says. “The other day, someone burned popcorn in our office microwave right next door to me, and I didn't know about it until I saw smoke coming around the door.” (One plus: his wife appreciates the fact that he's taken over dog-pen cleaning duty.)

And nearly 10 years after his head injury, Moses Abelman still hasn't recovered much of his sense of smell or taste. “I burned potatoes in the oven a while back, and people would come in days later and ask what was burning,” he says. “I couldn't smell a thing.”

SELF-HELP STRATEGIES

Even when there's no specific treatment to bring back a lost sense of smell or taste, people like Abelman can still adapt their lives in ways that allow them to enjoy a meal, socialize, and protect themselves from dangers such as gas leaks and spoiled foods. (See box, “Safety and Cleanliness Precautions,” page 27.)

At the Austin smell and taste clinic, Dr. DeVere and his staff—which includes food consultant Marji Calvert, a hotel catering manager—teach patients how to adapt their cooking and menu choices.

For example, they can make the most of the fact that the system enabling us to perceive basic tastes (sweet, sour, salty, bitter, and “umami”—a Japanese word meaning savory) is generally separate from our sense of smell, which plays an important role in our perception of specific flavors (like strawberry or vanilla or chocolate). The basic tastes usually remain intact even when flavor perception is lost due to impaired smell.

By adding spices, cooking with MSG (which increases the savory taste of food), and marinating dishes in sweet or sour marinades like cooking wines, fruit juices, and sweet-and-sour sauce, people with smell and taste impairments can bring a lot of life back to their dinner table. Some people report headaches or other reactions to MSG, but researchers have found no definitive link between these symptoms and MSG, and any short-term reactions do not appear to be dangerous.

Abelman prepares dishes with a lot of crunchy textures—he particularly loves deli-style sour pickles. “I get the sour taste and the salt taste and the crunch,” he says. “I also cook with a lot of garlic and chili powder, and with a lot of tomatoes because of their sweetness.”

A recent study involving cancer patients—who often experience loss of taste and smell following chemotherapy and radiation therapy—showed the effectiveness of these techniques. Half of the group received nutritional information only, while the other half also received flavor-enhancement products and foods such as bacon bits, sun-dried tomatoes, bananas, pear nectar, and butter and cheese extracts, which could be added to their foods to improve flavor.

“They were also taught how to chew their food well, to increase salivation, and allow aromas and food molecules to travel up the back of the nose to the smell organ, and were encouraged to move their tongues around to push the foods to the soft palate, which has many taste buds,” explains Dr. DeVere.

After eight months, the group receiving education and flavor enhancement had greater improvement in smell and taste perception and a slightly better quality of life. Their smell and taste hadn't actually changed, but they were enjoying both their food and their lives more.

“It's not a cure, but it is a compensation,” says Dr. DeVere. “There really are things that we can do to make life better with smell and taste disorders, but there has to be more education about it.”

CLICK AND CONNECT! Access the links in this article by reading it on neurologynow.com . On the Web site, you can also listen to a podcast with the editor-in-chief of Neurology Now Books™, Lisa Shulman, M.D. Dr. Shulman discusses how the book series will benefit patients and caregivers.

Figure. No caption available.

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Common Causes of Smell and Taste Disorders

* Normal aging (about 50 percent of the population between 65 and 80, and 75 percent of those over 80, have impaired smell and taste)

* Viral infections and allergies

* Traumatic injury

* Disorders of the nasal passages and sinuses (like polyps or nasal cancer)

* Use of certain medications

* Smoking

* Chronic medical conditions, like diabetes and kidney disease

* Certain neurologic disorders, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis

People with smell impairments can't rely on their nose to warn them of an unclean house, a hidden dog mess, or a fire in the next room. Dr. DeVere recommends a few precautions:

Figure. No caption available.

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1. Install working smoke detectors and natural gas or propane monitors in your home, and change batteries regularly.

2. Date all perishable foods to prevent accidental food poisoning.

3. Label and store all garden and household cleaning products properly.

4. Don't leave the room when food is in the oven or on the stove.

5. Bathe and shower and wash or dry-clean clothes on a regular schedule. Use perfume and other fragrances sparingly. Check with friends and family to make sure you're not overdoing it.

6. If you have pets, make periodic visual inspections for accidents—check corners and under furniture.

Introducing Neurology Now Books

The first book in the American Academy of Neurology's new series, Neurology Now Books™, is a guide for people with smell and taste disorders by Dr. DeVere. Navigating Smell and Taste Disorders, which published on September 1, is available now for sale from all major booksellers. (Go to patients.aan.com/go/neurologynowbooks for more information.) It contains 36 recipes, including the one reprinted here, as well as tips for preparing meals when a family member has trouble with smell and/or taste. All of the recipes are appropriate for the whole family, emphasize texture, temperature, spice, and taste (sweet, salty, umami, and sour), and include suggestions for enhancing these qualities further for individuals with a smell or taste disorder. They were also all tested by Dr. DeVere's patients.

Curried Chicken Salad

Serves 5 to 8

Preparation time: 2½ hours | Easy

This recipe, which features interesting texture, spice (Asian chili paste and Dijon mustard), and strong basic taste (juice of 5 limes), was very popular among our tasters. One hundred percent of tasters with smell or taste impairment enjoyed the standard recipe and all the variations. Those with normal smell and taste enjoyed the standard recipe as well as the first variation with additional yellow curry powder.

INGREDIENTS

2 to 3 pounds boneless, skinless chicken breast

3 tablespoons yellow curry powder Juice of 5 limes

1 each of yellow, green, and red peppers, diced

½ cup chopped, toasted pecans

1 bunch cilantro, chopped

4 ounces unsweetened coconut milk

½ cup Dijon mustard

2 tablespoons Asian chili paste

1 to 2 cups mayonnaise (depending on desired consistency)

Salt to taste

Cracked pepper to tastePreparation

Marinate chicken breasts in curry powder and lime juice for 1 hour. Grill chicken and allow to cool for 1 hour. Once cool, dice chicken into ½ inch cubes. Place chicken in a mixing bowl and add diced peppers, pecans, cilantro, coconut milk, mustard, chili paste, and mayonnaise. Mix well and season with salt and pepper to taste. Serve chilled.

VARIATIONS TO ENHANCE SMELL AND TASTE

TRY ADDING: 1 teaspoon yellow curry powder or 1 ounce unsweetened coconut milk or 1 teaspoon Asian chili paste.

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