Welcome
News & Info
Patient Information
Residency Program
Faculty & Staff
Specialty Services
Research
Courses & Symposia
Contact Us

Smell and Taste

Importance of Smell and Taste

Can you imagine a life without your senses of smell or taste? Memories of awakening to the smell of a hot breakfast filling the house would not exist. Your favorite food would seem just like any other food, or for that matter, like an empty spoon. Colorful, fresh-cut spring flowers would have the appeal of brown autumn leaves. One would never know that the last glass of milk in the refrigerator were was spoiled until the first nauseating gulp filled the mouth. The special scents of loved ones would no longer be there to remain with you even after that person had left your side.

There are many ways that the senses of smell and taste enhance, and even protect our lives on a daily basis. However, for most of us, this is easily taken for granted. It is also hard to understand the many ways that one's life would change after suffering a loss of the sense of smell or taste. While the loss of one's senses of smell or taste may seem rare, it is actually rather common. Estimates of the number of people in the United States alone who have experienced loss of smell or taste range from 2 up to 50 million people.

There are many causes of loss of smell or taste, including aging, medications, viral infection, sinus disease, head trauma, disorders of the immune system, psychiatric or neurological diseases, and surgery of the brain, head, and neck region. Virtually all age groups may be considered at risk for developing olfactory dysfunction. Some of the major causes of loss of smell and taste are discussed below, as well as how such problems are diagnosed, and where possible treated.

Disorders of the Sense of Smell

The loss of sense of smell can be described by the nature of the change in sense of smell, or the mechanism of injury to the smell apparatus. Changes that may occur include complete loss of smell, reduced sensitivity to smell, alteration in smell (when a known odor smells different than expected or even bad), and hallucinations of smell (smelling a particular odor when no real odor is present). Almost any such changes can be experienced regardless of the mechanism of the loss. A person may experience more than one of these changes either at the same time or at different times due to the same injury.

The two major categories of malfunction of the smell, or olfactory , system are blockage of the nasal passages (conductive loss), or damage to the smell sensors, called receptor cells, or nerve and brain pathways involved in the sense of smell (sensory-neural loss). Nasal blockage may be caused by a deviated septum, nasal polyps, nasal tumors (rare), or even allergies causing swelling of the lining tissues within the nasal passages. In many cases, these issues can be corrected with medication, or surgery, resulting in improvement in the sense of smell. Damage to the sensors or nerves of the olfactory system may occur anywhere between the upper nasal passage, where the sensory cells are located, and the brain, where information from the sensors is decoded, and a particular odor sensation is created in the mind. Unfortunately in most cases when such damage has occurred, no treatment is available, although spontaneous recovery may occur in some cases.

Causes of Impaired Smell

Disorders of the Sense of Taste

Similar to loss of sense of smell, the loss of taste can also be described by the nature of the change, or the mechanism of injury to the taste apparatus. Changes that may occur include complete loss of taste, reduced sensitivity to taste, alteration in taste (when a known food or substance tastes different than expected or even bad), and hallucinations of taste (experiencing a particular taste when nothing is present in the mouth). Again any, or more than one such change can be experienced regardless of the mechanism of the loss.

The two major categories of malfunction of the taste, or gustatory , system are changes in amount or quality of saliva, or damage to the taste buds in the tongue, or the nerve and brain pathways involved in the sense of taste. The amount of saliva may be reduced by dehydration, medications (diuretics or "fluid pills" and antihistamines used to treat allergy are common examples), surgical removal of saliva glands, previous radiation treatment for cancer of the mouth or throat, or immune system dysfunction affecting the saliva glands (Sjogren's Syndrome). This can sometimes be improved by changing medications that reduce the saliva, or taking a medication that increases the amount of saliva produced. Damage to the taste buds or nerves of the gustatory system may occur anywhere between the tongue, where the sensory cells of the taste buds are located, and the brain, where information from the sensors is decoded, and a particular taste sensation is created in the brain. Unfortunately in most cases when such damage has occurred, no treatment is available, although spontaneous recovery may occur in some cases.

It should be noted that in many cases, loss of sense of taste is actually the result of loss of sense of smell, despite a normally working taste system. Whenever foods are placed in the mouth, vapors pass up the back of the throat and reach the smell sensors in the nose. Thus the "flavor" of foods is actually a combination of the taste, as picked up by the taste buds on the tongue, and the smell picked up by the smell sensors in the nose. When the sense of smell is lost, a severe reduction in the "flavor" of foods is appreciated for this reason, even when the taste system is working normally.

Causes of Impaired Taste

Evaluation of Changes in Taste or Smell

People experiencing a loss of sense of smell or taste need a thorough evaluation by an ear, nose and throat physician (otolaryngologists). This will include a thorough medical history, and detailed examination focusing on the nasal passages, mouth and throat. The examination will usually include use of a small, lighted telescope to view the upper reaches of the nasal passages, where the smell sensors are located, and to look for signs of treatable causes of loss of sense of smell. In some patients an Xray of the sinus area (a CT or "CAT" scan), or an Xray of the brain (usually a magnetic resonance image, or "MRI") will be recommended in an effort to identify the cause of loss, and to rule out unlikely, but potentially life-threatening causes of the loss such as stroke or brain tumor.

In order to document the nature (smell, taste, or both) and severity of the loss, most patients will have testing of the senses of smell and/or taste performed. This can be done a number of ways. At the Smell and Taste Clinic of Virginia Commonwealth University, the sense of smell is tested in two ways. First, the sensitivity of the sense of smell is tested by seeing at what concentration, or strength, a patient is able to detect an odor (threshold test). Second, the ability of the patient to identify a number of common odors is tested (odor identification test). The complete test takes approximately 30 - 60 minutes to complete. The sense of taste is tested by seeing if a patient can detect and identify the four basic tastes (salty, sweet, bitter, sour) when small amounts of solution are applied to specific areas of the tongue.

Treatment of Smell or Taste Disorders

Loss of sense of smell caused by disorders of the nasal passages often can be treated. The goal is to improve airflow through the nose and inflammation within the nose and sinuses. This might involve antibiotics and decongestants for treatment of sinus infection, antihistamines, steroid sprays, or allergy shots for treatment of allergy, or surgery for deviated septum or chronic sinus infection. Disorders causing damage to the sensors or nerves of the olfactory system often cannot be treated. If the problem might have been caused by a medication, stopping or adjusting the dosage of the offending medication may lead to improvement. In most other cases the only hope is for regrowth and recovery of the damaged sensors or nerves. For example, in cases of loss of smell caused by head trauma, about 30% of patients experience recovery, which can occur even over 1 year past the injury .

When no specific treatment is available, or no recovery has occurred, patients need to be informed about the specific risks associated with their loss of sense of smell, with particular regard to the potential impact on their occupation. Patients should also be advised to institute protective measures to avoid potentially life-threatening events. Installation and regular maintenance of smoke and natural gas detectors is of paramount importance. Similarly, regular inspection and maintenance of natural gas appliances is recommended. Written dating of perishable food items, and their routine inspection by a friend or family member with normal sense of smell should minimize the potential for food poisonings. These simple measures, although not curing the underlying loss of smell, can help patients deal with their loss of smell, lessen the risk of life-altering consequences, and improve quality of life.

In some cases, a loss of the sense of taste can also be treated. If the loss of taste is actually due to changes in the sense of smell, treatment of this loss as outlined above will be helpful. If the loss was brought on by changes in saliva, altering or discontinuing medications such as antihistamines or fluid pills, increasing fluid intake, or taking medication that stimulates the saliva glands to produce more saliva (pilocarpine, in pill form), can all lead to improvement in taste. The presence of abnormal or displeasing taste sensations due to sinus drainage, gastric reflux, or dental disease can be treated with proper management of these problems. In most cases of taste loss caused by nerve or brain dysfunction, no treatment exists, and again only patient counseling is available. The primary danger with taste loss is malnourishment due to reduced interest in food. To avoid this, enhancement of meal enjoyment can be accomplished by using "visual cues" in food preparation in the form of colors or textures, varying food temperatures, as well as use of various condiments and seasonings depending on the type of taste loss present.

To schedule an evaluation of your sense of smell or taste please call:

(804) 628-4ENT (628-4368) and ASK for Holly McKay, RN.
All medical notes should be faxed to (804) 828-8299

Smell and Taste Clinic

For more information about the senses of smell and taste, and disorders affecting them, contact:

National Institute on Deafness and Other Communication Disorders (NIDCD)
Office of Health Communication and Public Liaison
31 Center Drive , MSC 2320, Bethesda , MD 20892-2320
Phone: (301) 496-7243 FAX: (301) 402-0018
E-mail: marin_allen@nih.gov
Web Address: http://www.nih.gov/nidcd/health/st.htm

American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS)
One Prince Street , Alexandria , VA 22314
Phone: (703) 519-1589 FAX: (703) 299-1125
E-mail: entinfo@aol.com
Web Address: http://www.entnet.org/smelltaste.html