Name of Symptom/Sign:
Ageusia (pronounced ay-GOO-see-uh) is the loss of tastefunctions of the tongue, particularly the inability to detect sweetness, sourness, bitterness, and saltiness. It is typically a symptom of anosmia- a loss of the senseof smell. Because the tongue can only indicate texture and differentiate between sweet, sour, bitter and salty, most of what is perceived as the sense of taste is actually derived from smell. True Aguesia is relatively rare compared to the milder forms of taste loss: hypogeusiaand dysgeusia. Hypogeusia represents a partial loss of taste whereas dysgeusia denotes a distortion or alteration of taste.
- 1 Diagnosis
- 2 Causes
- 2.1 Neurological Damage
- 2.2 Problems with the Endocrine System
- 2.3 Other Causes
- 3 Sources
In order to discover the extent of the Aguesia, scientists attempt to discern the minimum level of a chemical that a patient can detect by taste. Patients may also be asked to compare various concentrations of chemicals in order that the doctor may ascertain what level of intensity that the patient can differentiate. Various methods are used, including the "sip, spit, and rinse" test as well as direct application of chemicals to the tongue.
Aguesia is typically a function of the loss of the sense of smell, but tissue damage to the nerves that support the tongue can also cause ageusia, especially damage to the Lingual Nerve and the Glossopharyngeal Nerve. The Lingual Nerve passes taste for the front two-thirds of the tongue and the Glossopharyngeal Nerve passes taste for the back third of the tongue. Neroulogical disorders such as Bell's Palsy, Familial Dysautonomia, and Multiple Sclerosiswill cause similar problems to nerve damage.The lingual nerve (who is a branch of the facial nerve) can also be damaged during otologic surgery giving place to a feeling of metal taste.
Problems with the Endocrine System
Vitamin deficiency, namely vitamins B3and Zinc, could lead to problems with the Endocrine system, which may in turn lead to taste loss or alteration. Disorders of the Endocrine Sytem such as Cushing's Syndrome, Hypothyroidismand Diabetes Mellituscould lead to similair problems. Ageusia can also be caused by medicinal side-effects from Antirheumatic Drugssuch as Penicillamine, Antiproliferative drugssuch as Cisplatin, ACE Inhibitors, and other drugs including Azelastine, Clarithromycinand Zopiclone.
Local damage and inflammation that interferes with the taste buds or local nervous system such as that stemming from radiation therapy, Glossitis, tobacco abuse, and denture use will also cause Aguesia. Other known causes of Ageusia include loss of taste-sensitivity from aging (resulting in a difficulty detecting salty or bitter taste), Anxiety Disorder, Cancer, Renal Failureand Hepatic failure.
- MedTerms Online Medical Dictionary. "Ageusia". Retrieved April 15, 2005.
- Family Practice Notebook. "Taste Sensation". Retrieved April 15, 2005.
- Massachusetts Eye and Ear Infirmary. "Taste Disorders". Retrieved April 15, 2005.
Categories: Gustation| Otolaryngology
This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Ageusia Wikipedia article Ageusia.