Ageusia

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Ageusia
Pronunciation
SpecialtyNeurology

Ageusia (from negative prefix a- and

smell. Because the tongue can only indicate texture and differentiate between sweet, sour, bitter, salty, and umami, most of what is perceived as the sense of taste is actually derived from smell. True ageusia is relatively rare compared to hypogeusia – a partial loss of taste – and dysgeusia – a distortion or alteration of taste.[1][2]

Causes

The main causes of taste disorders are head trauma, infections of upper respiratory tract, exposure to toxic substances, iatrogenic causes, medicines, glossodynia (burning mouth syndrome (BMS))[2] and COVID-19.[3]

Head trauma can cause lesions in regions of the

temporal lobes; it can also cause damage to neurological pathways involved in transmission of taste stimuli.[citation needed
]

Neurological damage

Tissue damage to the nerves that support the tongue can cause ageusia, especially damage to the chorda tympani nerve and the glossopharyngeal nerve. The chorda tympani nerve passes taste for the front two-thirds of the tongue and the glossopharyngeal nerve passes taste for the back third of the tongue. The lingual nerve (which is a branch of the trigeminal V3 nerve, but carries taste sensation back to the chorda tympani nerve to the geniculate ganglion of the facial nerve) can also be damaged during otologic surgery, causing a feeling of metal taste.[citation needed]

Problems with the endocrine system

Deficiency of

antiproliferative drugs such as cisplatin, ACE inhibitors, and other drugs including azelastine, clarithromycin, terbinafine, and zopiclone.[citation needed
]

COVID-19

Main article: Symptoms of COVID-19 § Loss of taste and chemesthesis

Agnosia and anosmia in COVID-19 patients occur independently of nasal obstruction or other rhinitis symptoms, likely attributed to direct viral damage to olfactory and gustatory receptors[4]

In April 2020, 88% of a series of over 400

olfactory dysfunction).[5] Research suggests that the loss of taste resulting from COVID-19 might be caused by impairments to the gustatory (and olfactory) system.[6]

Other causes

Local damage and inflammation that interferes with the taste buds or local nervous system, such as that stemming from

aging (causing a difficulty detecting salty or bitter taste), anxiety disorder, cancer, kidney failure and liver failure
.

Diagnosis

Ageusia is diagnosed by an

otolaryngologist, who can evaluate a patient's loss of taste among other things. To do this, a specialist will look into any other factors that could be causing ageusia, such as examining the head, nose, ears, and mouth. An otolaryngologist can also conduct a series of tests to assess the severity of ageusia, which includes identifying specific tastes that the patient can sense or recognize.[7][8]

References

  1. ^ "Taste Disorders". Massachusetts Eye and Ear Infirmary. Retrieved 30 November 2018.
  2. ^
    PMID 22558054
    .
  3. PMID 32837952
    .
  4. ProQuest 2398912838
    – via ProQuest.
  5. PMID 32253535
    .
  6. PMID 32237238
    .
  7. ^ "Ageusia: Causes, Symptoms And Treatment". Netmeds. Retrieved 2021-03-26.
  8. ^ "Taste Disorders: Get Facts About Causes, Treatment & Symptoms". MedicineNet. Retrieved 2021-03-26.

External links

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