Anosmia

Anosmia is the lack of olfaction, or a loss of the ability to smell. It can be either temporary or permanent. A related term, hyposmia, refers to a decrease in the 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.

While termed as a disability, anosmia is often viewed in the medical field as a trivial problem. This is not always the case—esthesioneuroblastoma is a very rare cancerous tumor originating in or near the olfactory nerve.

Additional recommended knowledge

How to ensure accurate weighing results every day?

Essential Laboratory Skills Guide

Daily Visual Balance Check

Diagnosis

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

Smell vs. taste

It should be emphasized that there are no more than 6 distinctive tastes: salty, sour, sweet, bitter, umami and possibly fatty acids. The 10,000 different scents which humans usually recognize as 'tastes' are often actually 'flavor', which many people who can smell confuse with taste. This sense of 'flavor' is greatly diminished by a loss of the sense of smell, often causing those with sudden onset anosmia a great deal of concern when all food suddenly loses its flavor. When one can't smell anything, food loses most of its flavor, as when wearing nose plugs or during a cold. Congenital anosmics taste this way their entire life and are generally used to it, but someone who becomes anosmic has trouble with everything "tasting like wet cardboard"^{[citation needed]}.

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, body odor, 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, even to the point of impotency, which often preoccupies younger anosmic men.^{[2][dubious – discuss]}

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, much to the surprise of their parents.^{[citation needed]}

Congenital anosmics will usually go through life confused about their inability to smell. Most are not believed when they tell their parents (usually in teenage years) and many will have to go through what feels like harassment by friends and family--"Mmm, doesn't that smell good? Oh, sorry, I forgot. You can't smell." And they will constantly have to prove themselves of their unknown disability. When an anosmic tells another person they cannot smell, the reaction varies from shock to disbelief to boredom to "Oh my gosh, you're so lucky!" Most congenital anosmics go throughout life without meeting another anosmic.

Causes

A temporary loss of smell can be caused by a stuffy 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 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.^[3] 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)^[4]
• Nasal polyps
• Smoking
• Head trauma, damage to the ethmoid bone^[5]
• Dementia with Lewy bodies
• Parkinson's Disease^[6]
• Alzheimer's Disease^[7]
• Toxins (especially acrylates, methacrylates^[8] and cadmium^[9][10])
• Old age^[11]
• 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.^[12]

Associated conditions

• Cystic Fibrosis
• Kallmann syndrome
• Zinc deficiency
• Parkinson's disease
• Alzheimer's disease
• Cadmium Poisoning
• Holoprosencephaly
• Allergies
• primary amoebic meningoencephalitis caused by Naegleria fowleri
• Refsum Disease

See also

• Parosmia

Notable anosmiacs

• Mary Baker Eddy
• Kevin Downs
• Scott Kurtz
• Arjen Anthony Lucassen
• Paul Osterberg
• Mike "Skip" Prosser
• Bill Pullman
• Simon Tatham
• Benjamin Urrutia
• Stevie Wonder
• William Wordsworth

References