AGEUSIA, HYPOGEUSIA AND DYSGEUSIA
Taste is established on the sensitivity to chemicals by specific taste cells (taste buds) in the mouth. The tongue, mouth, throat, larynx, and esophagus, all have taste buds. Each taste bud has its own set of receptor cells. Afferent nerves (nerves which carry impulses to the brain or spinal cord) make contact with the receptor cells at the base of the taste bud. The salivary glands keep the taste buds moist with saliva.
Ageusia is the loss of taste of the tongue. A person cannot differentiate in the taste of food which are sweet, bitter, sour, salty or umami (meaning "pleasant/savory taste"). Sometimes, it is confused with Anosmia (the loss of the sense of smell). Anosmia and Ageusia are closely interrelated though, the human brain often interprets the smell to feel its taste. Similar diseases are Hypogeusia, where there is a partial loss of taste; and Dysgeusia where there a distortion or alteration of taste. True Ageusia however, is relatively rare.
DIAGNOSIS OF AGEUSIA
Chemicals or food of different taste are given to patient to check if he can differentiate.
CAUSES OF AGEUSIA
Neurological Damage : Tissue damage to the nerves supporting the tongue.
Problems of Endocrine System : Deficiency of vitamin B3 (niacin) and zinc.
Medicinal side effects : Antirheumatic drugs like penicillamine, antiproliferative drugs such as cisplatin, ACE inhibitors, and other drugs including azelastine, clarithromycin and zopiclone.
Local damage, inflammation with the taste buds, damage because of radiation therapy, glossitis, tobacco use, and denture use also cause Ageusia. Other causes include aging, anxiety, cancer, renal (kidney) failure and liver failure.
Hypogeusia is the reduced ability to taste things (to taste sweet, sour, bitter, or salty substances). The complete lack of taste is referred to as Ageusia. Causes of hypogeusia include the chemotherapy drug bleomycin, an antitumor antibiotic.
Dysgeusia is a distortion in the sense of taste. Dysgeusia is frequently related with Ageusia (complete loss of taste), and Hypogeusia (reduced sense of taste). A distortion in taste or smell may indicate the presence of any disease, or the advancing of any disease.
CAUSES OF DYSGEUSIA
Common causes of Dysgeusia include Chemotheraphy, asthma treatment with Albuterol, and zinc deficiency.
SYMPTOMS OF DYSGEUSIA
Taste is usually metallic, occasionally with smell being the only symptom.
PERSISTENCE OF DYSGEUSIA
If due to gum disease, dental plaque, temporary medication, influenza; Dysgeusia should disappear once the cause is removed.
If lesions exist in the taste path, or nerves are damaged, Dysgeusia may be permanent.
- Study over taste, swallowing, salivation, oral pain, chewing, previous ear infections (sometimes hearing problems), oral hygiene, and stomach problems.
- Tests for diseases like Diabetes Mellitus, Hypothyroidism, or Cancer.
- Examination of tongue and the oral cavity, inspection of ear canal.
- Chemotherapy : antineoplastic chemotherapy is a major cause.
- Zinc Deficiency
- Medicines/Drugs affecting taste : There are different drugs which can cause Dysgeusia
Idiopathic (disease with no clear cause) Dysgeusia is very common. Factors include gastric reflux, lead poisoning, and diabetes mellitus. Certain pesticides damage the taste buds and nerves of the mouth.
- Artificial Saliva and Pilocarpine : Stimulates the salivary glands to actively produce saliva.
- Zinc supplementation (Zinc Gluconate), Zinc infusion in Chemotherapy
Altering Drug Therapy
- Eprosartan : To reverse the effect of drugs that may have caused Dysgeusia.
- Alpha Lipoic Acid (ALA) : It is an antioxidant made naturally by human cells, and has been proven effective in the treatment of Burning Mouth Syndrome and Dysgeusia.
- Use non-metallic silverware
- Avoid bitter tasting foods
- Eat foods high in protein
- Frequently brushing teeth and utilizing mouthwash
- An altered taste may reduce food intake (anorexia-loss of appetite) leading to weight loss, or malnutrition, or decline in health.
- Caution to be taken when adding sugar and salt to food, and not to over-add to compensate for their lack of taste.
- Elderly are more at risk since they are often on multiple medications.
- In patients undergoing chemotherapy, taste distortions can often be severe.