Smell disorders are conditions affecting sense of smell of a person. The sense of smell comes from specialized sensory cells called olfactory sensory neurons that are found in a small patch of tissue inside the nose and connect directly to the brain. Smell reaches the olfactory sensory neurons through either the nostrils or through a channel that connects the roof of the throat to the nose. Without these olfactory sensory neurons the sense of smell cannot work.
Smell disorders include either a loss in the ability to smell or changes in the way a person perceives odours. People with smell disorders either don’t smell odours or perceive some or all odours differently than other people. The sense of smells and the sense of taste work hand in hand, therefore a person with smell disorders may also believe to be having taste disorder as well.
While the sense of smell may grow weak with age, smell disorders are usually a result of a poor development of the smell system. Problems like viral infection or a head injury may also trigger sense disorders.
There are several types of smell disorders depending on how the sense of smell is affected. Smell disorders are usually categorised into following types
If the person has a reduced ability to detect odours however there is still some sense of smell working it is called hyposmia. The affected person is able to smell odours however the sense is much weaker than normal.
A smell disorder is called anosmia if a person has completely lost the sense of smell. Problems such as an injury or infection may result in complete loss of sense of smell. In rare cases, a child may be born without a sense of smell. Such a condition is called congenital anosmia. Anosmia is usually less common as compared to hyposmia.
This type of smell disorder involves a change in the perception of odours. A person with parosmia usually perceives a familiar ordour differently. This condition may even turn a pleasant ordour into a foul one and vice versa.
When a person has a false sense of smell it is called phantosmia. The person with phantosmia gets a sensation of an odour that isn’t there.
Smell disorders have many causes, with some more obvious than others. Most people who develop a smell disorder have experienced a recent illness or injury. Common causes of smell disorders are growths in the nasal cavities, head injury, hormonal disturbances, aging, sinus and other upper respiratory infections, smoking, dental problems, medications, radiation for treatments and conditions that affect the nervous system such as Parkinson’s disease or Alzheimer’s disease.
Smell disorders are usually diagnosed by an ENT specialist through a physical examination of the nose, and throat; a review of medical history, and a smell test. Smell disorders are usually treated by treating the causative agent. A person may recover the ability to smell one the cause of the disorder has been treated. Some people recover their sense of smell on their own.
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