The Taste and Smell Clinic at UConn Health appreciates your interest. As of 1996, we have gathered information on over 3,000 people with taste and/or smell problems. Over 1,000 of these individuals have traveled to our Center for comprehensive evaluation. Basically, we provide our patients with the following services: (1) Documentation of the type and severity of the taste and/or smell problem; (2) Determination of probable cause(s); (3) Management, if the condition is determined to be treatable (less than half of patients); and (4) Computerized maintenance of patient records (allowing future contact should an appropriate treatment become available).
It is estimated that approximately 2 million adult Americans have a taste and/or smell disorder. These include anosmia (complete smell loss), hyposmia (partial smell loss), ageusia (complete taste loss), hypogeusia (partial taste loss), parosmia (smell distortion or phantom smell), and dysgeusia (persistent abnormal taste). There are actually three "chemosensory" systems in the nose and mouth. The first, olfaction, is the ability to detect and identify odors. The second is gustation or taste. Taste function is limited to detection and identification of sweet, sour, salty, and bitter substances in the mouth. The third sense, the "common chemical sense", is the ability to detect the irritating properties of substances in the mouth and odors in the nose. Through the common chemical sense, we perceive the burn of chili pepper and the tingle of ammonia.
Information about taste is picked up by numerous taste buds distributed throughout the oral cavity. Smell information is processed by specialized nervous tissue at the very top of the nasal cavities. The common chemical sense is transmitted through many tiny nerve endings in the linings of the nose and mouth. Information from these three senses is transmitted via a number of separate paths to the brain.
The terms "flavor" and "taste" are often confused. Flavor is determined by the aroma (smell), taste (sweet, sour, salty or bitter quality), texture, temperature and spiciness (or irritation) of food and beverages. All of these sensory experiences together form "flavor." Frequently, when individuals say they cannot taste, they are really telling us that they cannot appreciate the flavor of food. As the aroma of food contributes to about 3/4 of its flavor, these individuals usually have suffered a loss of smell ability only.
Once the type of chemosensory problem is determined, preferably through testing, the cause needs to be identified. Although taste and smell abnormalities are linked to many medical and dental conditions, most are caused by only a handful of disorders.
Some people are born without an ability to smell. This is called congenital anosmia. There are many possible reasons for a life-long inability to smell. The most commonly described, although it occurs in only 1 in 50,000 females and 1 in 10,000 males, congenital anosmia is Kallman's syndrome. This syndrome can run in families and is manifested chiefly by smell loss and hormonal problems that prevent the development of normal sexual characteristics. In women, this might be evidenced by lack of onset of normal menstruation, poor breast development, sparse or absent axillary and pubic hair. Men might exhibit small testicles and penis, sparse or absent facial, axillary or pubic hair. Sterility might be present. If you can never remember being able to smell, and have noted abnormal sexual development in yourself or in close family members, you might want to consult an endocrinologist (hormone specialist) in your area for evaluation.
Some individuals who can not remember ever being able to smell were born with a normal smell system, but lost this ability during childhood. The two most likely causes for this are head trauma and viral infection. Data obtained from adults show that even insignificant head trauma can lead to permanent and total smell loss. Minor blows to the head are common in childhood. It is likely that some children labeled as "congenital anosmics" were born with an intact smell system, but damaged this system during childhood. Viral respiratory infections (the common cold) have also been known to damage the smell system (see below). It is possible that some children sustained permanent injury to the smell system through a viral infection when very young.
Viral Damage and Nasal/Sinus Disease
The specialized smell tissue at the top of the nose can also be damaged by environmental agents, such as chemicals, metal dusts and wood dusts. These can be encountered in the home or workplace. Both acute and chronic exposures have been reported to cause both temporary and permanent smell losses.
Rarely, a specific type of benign brain tumor can cause smell loss. Any individual who has developed a gradual decrease in smell function and who is not determined to have any of the other possible causes listed above should consider evaluation for this tumor. Though rare, it is treatable.
Taste and smell problems have also been linked to many medical illnesses, and have been reported as a side effect to medications, surgery and radiation therapy. These are too numerous to list here. For a more comprehensive list, please refer to the following reviews: Mott AE and Leopold DA, "Disorders in Taste and Smell", Medical Clinics of North American, 6:1-33, 1991; Mott AE, Grushka M, and Sessle BJ, "Diagnosis and Management of Taste Disorders and Burning Mouth Syndrome", Dental Clinics of North America, 37(1):1993.
Special Instructions for Patients with Smell Loss
The ability to smell allows early detection of dangerous substances in our environment and the loss of this sensory system places an individual at risk. These risks can be minimized, however, by instituting certain precautionary measures. If you have not already done so, please make certain smoke detectors are present and functional in your home. They should be checked every month. Also, if you are exposed to potential gas leaks, we would encourage you to purchase a gas detector. Information about this may be obtained through your local gas company or a marine store (the inability to detect smoke and/or leaking gas are two potential hazards for those without smell function). Patients should also be exceptionally careful with food and beverages. Refrigerated food should be date-labeled and stored at appropriate temperatures. All food should be inspected prior to preparation and eating. Food that looks spoiled should be discarded. Preferably, a member of the household with an intact smell system should check any food or beverage that is questionable.
We hope this information is useful to you. Please let us know if we can provide additional information to you or your physician/dentist.