| Off the scent
AT a typical Asian cuisine outlet, everyone would be
enjoying the aroma of good food seeping through the doors of the
kitchen. Imagine the feeling when the food is served. When the sensation
of smell is lost, it is comparable to blindness and deafness. People who
suffer from anosmia are unable to smell anything.
Wikipedia defines anosmia as lack of olfaction or a loss of the ability
to smell. Many people may not realize they have this disorder until they
encounter a situation whereby it is obvious that they had missed an
odor or smell. It is distressing and could lead to depression in some.
There is another condition called "hyposmia" where an individual’s
ability to smell is diminished. He would be able to catch the smell only
when the odor/fragrance intensity is high.
How do we smell?
The earliest research on the mechanism of smell was done in 1756 by
Linnaeus, a Swedish botanist. Decades later, scientists have
differentiated various molecules and described them as aromatic,
fragrant, repulsive, ethereal, resinous, spicy, burned, putrid and so
on. Smell must be either in gaseous or volatile liquid form for it to be
perceptible.
In the roof of our
nose are sensitive nerve endings and nerve cells that form the olfactory
system. These can detect odors in the air. The level of sensitivity
varies from person to person. Some animals have greater sensitivity to
the smell of certain odors. We even have canines that can sniff out
pirated CDs.
Our system of smell is unique as sensitivity would diminish upon
continuous exposure to a particular smell.
An odor can also mask another, especially if one is much stronger, or
the combination of the two yields no odor at all.
There are 16 chemical elements that produce odor: Hydrogen, carbon,
silicon, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen,
sulphur, selenium, tellurium, fluorine, chlorine, bromine and iodine.
Halogen and ozone are also odorous elements.
Losing the smell sensation
It is postulated that when air flow towards the roof of the nose is
blocked, the sense of smell would decrease. This occurs commonly when we
suffer viral influenza which causes an inflammation within the nose.
Patients with allergic rhinitis would suffer the same fate as there
would be inflammation that almost occludes the air passage. It prevents
air flow carrying molecules containing substances which could stimulate
the sense of smell from reaching the olfactory nerve endings. Nasal
polyps, deviated septum, tumors and deformed bones within the nose
could also contribute to anosmia.
Medications such as nasal vasoconstrictors could lead to a permanent
anosmia, scientifically known as rhinitis medicamentosa. It also causes
crusting and bleeding. Treatment is far from successful in these cases.
Other probable causes of anosmia would be tumors of the nose or brain,
head trauma and a variety of endocrine, nutritional, Alzheimer’s
dementia, and nervous disorders.
Treating anosmia
It is difficult to promise recovery and total cure for anosmia. In some
cases, if the probable cause is identified, the chance of regaining the
sense of smell is encouraging.
The common treatment method would be to clear the offending obstruction
in the nose. Inflammation caused by allergy or infection would be
cleared with the use of nasal steroids and antibiotics. Polyps may have
to be removed surgically if persistent, and other bony/cartilage
deformities could be corrected.
Anosmic patients with nerve defects have less chance of recovery. Viral
infections damage nerves and this is irreversible.
Hypothyroidism and poor control of diabetes mellitus may also slow down
recovery of the olfactory system.
Nutritional deficits may be reversed with zinc, vitamin A, thiamine or
any other specific nutrient that may be lacking. The evidence of its
effectiveness is yet to be proven.
Many patients suffer anosmia due to unknown causes which are not
amenable to specific treatment. Use of zinc sulphate is controversial as
again, it has not been proven effective.
Other remedies such as vitamins and tricyclic antidepressants have been
tested on some patients. It is advisable to eliminate toxins (eg.
cigarette smoke, airborne pollutants).
Conclusion
Anosmia is not a life-threatening problem but it could be dangerous as
sometimes poison fumes or the smell of fire are missed. This is common
in many individuals and a proper nasal examination by an ENT surgeon
would be warranted. |
