Anosmia: What causes the loss of smell?
Smell and the perception of odors
Smell is a very important sense. It helps us enjoy the beautiful smells around us, but also protects us by detecting unpleasant or dangerous odors. In addition, by perceiving the aromas of food, it highlights and enhances the taste pleasure.
The organ of smell is a small area in the upper and narrowest part of the nasal cavity, where the nasal septum joins the lateral wall. Specialized olfactory cells are stimulated by odors chemically. Fine nerve fibers, which penetrate the thin perforated bone of the base of the skull, transmit the stimulus from the nose to the first brain stations, the olfactory bulbs, which are located directly above. From there, specialized nerves carry the information to the olfactory centers of the brain, where the odors are recorded and encoded.
What can cause a decrease in the sense of smell?
About 1-2% of people suffer from a reduced sense of smell (hyposmia) or even its complete elimination (anosmia). In most cases, the problem is temporary, such as in the context of a cold, or is reversed with appropriate treatment, such as in chronic rhinitis and nasal polyps, but it can also be permanent.
Some possible causes of permanent hyposmia or anosmia are:
- Exposure to irritants: Smoking, toxic paints, solvents, ammonia, cocaine.
- Age-related degeneration
- Degenerative brain diseases: Parkinson’s, Alzheimer’s, multiple sclerosis.
- Craniocerebral injury: Many times, just the vibration of the injury can cause the brain to suddenly slide against the base of the skull and sever the fine olfactory fibers.
- Tumors of the nose and brain
- Surgeries on the nose or brain
- Endocrinological diseases: Hypothyroidism, pregnancy, Addison, Cushing, Diabetes Mellitus.
- Psychiatric diseases
- Radiation therapy
How is hyposmia diagnosed?
Patients complain that they cannot smell perfumes and other odors, while they also feel that the taste of food is altered. The otolaryngologist will perform a detailed general ENT assessment and will carefully examine the nose with an endoscope.
The sense of smell is traditionally tested by presenting various odors, such as coffee, tobacco, cocoa or spices. In Greece, a test with twelve scented markers has recently been available, which the patient smells and then chooses the correct one from four answers. This test is performed at the Athens Rhinology Center, at the Athens Medical Center.
In addition to the above, a CT scan or MRI scan and blood tests may be required.
Can hyposmia and anosmia be treated?
Fortunately, the most common causes of temporary hyposmia are upper respiratory tract infections, which with appropriate supportive treatment resolve within a few days. Chronic rhinosinusitis, with or without polyps, often causes long-term loss of smell and requires specialized evaluation and treatment by a specialist. In cases where the diagnostic test does not result in a specific cause, an oral cortisone regimen may be useful, especially when the total duration of the problem does not exceed six months.
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