Anosmia

From Wikipedia, the free encyclopedia

Anosmia (ænˈɒz.mi.ə) is a lack of functioning olfaction, or in other words, an inability to perceive smells. It can be either temporary or permanent. A related term, hyposmia, refers to decreased ability to smell, while hyperosmia refers to an increased ability to smell. Some people may be anosmic for one particular odor. This is called "specific anosmia" and may be genetically based.

Diagnosis
Anosmia can be diagnosed by doctors by using scratch-n-sniff odor tests[citation needed] or by using commonly available odors such as coffee, lemon, grape, garlic, vanilla and cinnamon.

Presentation
Anosmia can have a number of detrimental effects. Patients with sudden onset anosmia may find food less appetizing, though congenital anosmics rarely complain about this. Loss of smell can also be dangerous because it hinders the detection of gas leaks, fire, and spoiled food. The common view of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.

Losing an established and sentimental smell memory (e.g. the smell of grass, of the grandparents' attic, of a particular book, of loved ones, or of oneself) has been known to cause feelings of depression.[1]

Loss of olfaction may lead to the loss of libido, though this may not apply to congenital anosmics.[1]

Often people who have congenital anosmia report that they pretended to be able to smell as children because they thought that smelling was something that older/mature people could do, or did not understand the concept of smelling but did not want to appear different from others. When children get older, they often realize and report to their parents that they do not actually possess a sense of smell, often, to the surprise of their parents.[citation needed][1]

Causes
A temporary loss of smell can be caused by a blocked nose or infection. In contrast, a permanent loss of smell may be caused by death of olfactory receptor neurons in the nose, or by brain injury in which there is damage to the olfactory nerve or damage to brain areas that process smell (see olfactory system). The lack of the sense of smell at birth, usually due to genetic factors, is referred to as congenital anosmia. Anosmia may very occasionally be an early sign of degenerative brain diseases such as Parkinson's disease and Alzheimer's disease. Another specific cause of permanent loss could be from damage to olfactory receptor neurons due to use of certain types of nasal spray, i.e. those that cause vasoconstriction of the nasal microcirculation. To avoid such damage and subsequent risk of loss of smell from vasoconstricting nasal sprays, they should be used for only a short amount of time and only when absolutely necessary. Non-vasoconstricting sprays, such as those used to treat allergy related congestion are safe to use for extended periods of time.[2] Anosmia can also be caused by nasal polyps. These polyps are found in people with allergies, histories of sinusitis & family history. Individuals with cystic fibrosis often develop nasal polyps.

Causes of anosmia include:

Upper respiratory tract infection (e.g., sinusitis or the common cold)[3]
Nasal polyps
Hypothyroidism
Head trauma, damage to the ethmoid bone[4]
Dementia with Lewy bodies
Tumors of the frontal lobe
Parkinson's Disease[5]
Alzheimer's Disease[6]
Toxins (especially acrylates, methacrylates[7] and cadmium[8][9])
Old age[10]
Kallmann syndrome
Laryngectomy with permanent tracheostomy
Esthesioneuroblastoma is an exceedingly rare cancerous tumor that originates in or near the olfactory nerve. Symptoms are anosmia (loss of sense of smell) often accompanied by chronic sinusitis.[11]
Intranasal drug use
Samter's triad
Foster Kennedy syndrome
Cadmium poisoning
Smoking
This list is incomplete; you can help by expanding it.

Zicam controversy
On June 16, 2009, the U.S. Food and Drug Administration sent a warning letter to Matrixx Initiatives, manufacturer of an over-the-counter nasal spray for the common cold, Zicam. The FDA cited complaints that the product caused Anosmia. The manufacturer strongly denies these allegations, but has recalled the product and has stopped selling it. [12][13]