Anosmia
Anosmia is defined as a complete loss of the ability to detect odors, and it can significantly impact daily life. The condition may arise from various causes, including blockages in the nasal cavity due to nasal polyps or foreign bodies, as well as viral infections, head trauma, or congenital factors. Symptoms primarily consist of the inability to smell, which can last anywhere from several days to a lifetime. Treatment options depend on the underlying cause; for example, removing blockages through surgery or using steroids can be effective in some cases.
Individuals with anosmia may face challenges related to safety, such as the inability to detect smoke or spoiled food, prompting the use of smoke and natural gas detectors. Moreover, the loss of smell can affect the perception of flavor in food, leading to altered eating experiences. Those affected might find that enhancing food with texture or seasoning can help, although this may not suit everyone. Overall, anosmia not only influences sensory experiences but also raises practical concerns that individuals may need to address for their well-being.
Subject Terms
Anosmia
ANATOMY OR SYSTEM AFFECTED: Brain, nervous system, nose
DEFINITION: A complete loss in the ability to detect odors.
CAUSES: Blockage, viral infection, head trauma
SYMPTOMS: Inability to detect odors
DURATION: Several days to lifelong
TREATMENTS: Surgery to remove blockage, oral or systemic steroids
Causes and Symptoms
One of the causes of anosmia is a blockage in the nasal cavity such that odorant molecules cannot reach the olfactory receptors. This blockage can be the result of conditions such as nasal polyps, foreign bodies, or the temporary swelling that accompanies colds or allergies.
If the person was born without a sense of smell and the air passageways are open, then the cause of the loss is likely congenital. If there was once a sense of smell, then causes of the loss may include head trauma, an upper respiratory infection, drug toxicity, and a tumor. With head trauma—such as from a fall or an automobile accident—or degenerative brain diseases, there is a disruption in the ability of the olfactory nerves to send signals to the brain. When the cause is a viral infection, the person usually reports a cold or flu during which loss of the sense of occurred but did not return as the cold resolved. The reasons for permanent loss are not clear but likely involve a disruption in the neural pathways.
Treatment
Removing the blockage is the treatment in the case of a blocked air passageway. In the case of allergies, flu, or the common cold, as the swelling resolves the sense of smell usually returns. Nasal can be reduced by or surgically removed.
If the cause of the loss is head trauma, then a and/or topical course of steroids may help, although the is not good. For anosmia following a viral infection, the sense of smell sometimes returns gradually over a year or so. Steroids taken during or soon after the infection may be helpful. If the loss is from drug toxicity, then changes in medications may help.
Perspective and Prospects
Anosmia can present serious problems in the detection of smoke, spoiled food, body odors, or natural gas. People with anosmia should consider the use of smoke detectors (including one in the car) and natural gas detectors in the house. Because it is difficult to detect spoiled food, items in the refrigerator should be labeled with the date of purchase and care should be taken not to consume green or slimy foods. Concerns about body or breath odors can be addressed by practicing reasonable hygiene.
Because of the relationship between the sense of smell and the perception of flavor, most common foods do not “taste” right to those with anosmia. In this case, the perception of the flavor of food can be enhanced somewhat by adding texture or more salt or sugar. If the patient is preparing food for others, however, then these enhancements will not be well received by people with a functioning sense of smell.
Bibliography
de Melo, G.D., et al. "Neuroinvasion and Anosmia Are Independent Phenomena Upon Infection with SARS-CoV-2 and Its Variants. " Nature Communications, vol. 14, no. 4485, 26 July 2023, doi.org/10.1038/s41467-023-40228-7. Accessed 27 Mar. 2024.
Engen, Trygg. The Perception of Odors. New York: Academic Press, 1982.
Finger, Thomas E., Wayne L. Silver, and Diego Restrepo, eds. Neurobiology of Taste and Smell. 2d ed. New York: Wiley-Liss, 2000.
Gilbert, Avery. What the Nose Knows: The Science of Scent in Everyday Life. New York: Crown, 2008.
"Loss of Smell." Mayo Clinic. 2023, www.mayoclinic.org/symptoms/loss-of-smell/basics/definition/sym-20050804. Accessed 27 Mar. 2024.
Wolfe, Jeremy M., et al. Sensation and Perception. 2d ed. Sunderland, Mass.: Sinauer, 2009.