Hyposmia: Causes, Diagnosis And Treatment

Hyposmia, also known as microsmia, is the reduced ability to smell or detect odours ^[1] . A closely related variant of this condition is anosmia, wherein a person cannot detect any form of odours at all. Such olfaction problems can occur due to allergies, nasal polyps, head trauma and viral infections. In some cases, hyposmia can also be considered as an early sign of Parkinson's disease ^{[1] [4]} . When hyposmia affects a person for his or her entire life, the condition is known as Kallmann syndrome ^[2] .

Read on to know more about the causes, diagnosis and treatment of Hyposmia.

What Is Hyposmia?

When a person loses all or part of their sense of smell, then the condition is known as hyposmia ^[1] . According to research study data, the human olfactory system (which governs the sense of smell) can detect between 10,000 and 100 billion different odours ^[3] . The only symptom of this condition is the partial or complete loss of the sense of smell.

The olfactory information plays an essential role in keeping a person safe ^[4] . When a person loses his or her sense of smell, either partially or completely, he or she may fail to notice warning signs of safety such as the smell of gas, fire or spoilt food.

Causes Of Hyposmia

The possible causes of hyposmia include the following ^[5] :

• A head injury
• Allergies
• Smoking
• A deviated nasal septum
• A hormonal imbalance
• Dental problems
• Infections (such as flu)
• Polyps in the nose
• Chronic sinus issues

The following medications can affect the sense of smell ^[6] :

• Antibiotics such as ampicillin and tetracycline
• Antidepressants such as amitriptyline
• Antihistamines such as loratadine

The following are some of the other factors that can cause hyposmia:

• Use of recreational drugs ^[7]
• Radiation treatment
• Long-term exposure to certain chemicals
• Tobacco smoking

Diagnosis Of Hyposmia

If you feel that you have an impaired sense of smell, consult the doctor immediately before trying out over-the-counter medications. The doctor's first approach would be fetching answers to the following questions ^[8] :

• Does the patient take any medications?
• Can the patient taste foods?
• Can the patient smell some foods but not others?
• What other symptoms does the patient have?
• Did the patient have any allergies in the recent past?
• Did the patient recently have a flu-like infection?

Once the medical history of the patient has been reviewed, the doctor performs a physical examination of the patient's nose to see if there are any blockages in the nasal passages. The following tests are performed:

• MRI scan
• CT scan
• X-ray
• Nasal endoscopy (the nasal passages are examined using a thin tube that contains a camera) ^[9]

A scratch-and-sniff test ^[10] helps a doctor to determine if the person has hyposmia or anosmia. In the case of hyposmia, these tests measure the extent of the loss of smell.

Performing the tests help the doctor determine the structural changes within the nose. Imaging tests help in revealing if there's a polyp or any other form of abnormal growth that obstructs the nasal passages. Tests also help in determining if any form of tumour in the brain is the reason behind the alteration in the sense of smell.

Treatment For Hyposmia

Treatment options usually include medication, surgery and relevant therapies for the underlying cause. Surgery is recommended in case of the following ^[11] :

• Nasal polyps
• A deviated septum
• Other structural deformities

Medications such as steroids and antihistamines ^[12] are prescribed to calm any inflammation that could have resulted from an allergy or respiratory infection.

Prevention Of Hyposmia

There is no way one can prevent hyposmia. However, one can reduce the triggers. One should aim at minimizing the risk of contracting colds or bacterial infections by taking the following steps:

• Wash your hands often throughout the day
• Wash your hands after you touch public areas
• Whenever possible, try to avoid going near people who have flu.

Also, being familiar with the possible side effects of all the medications that you take can be quite helpful. Some medications come with a leaflet material that includes the possible side effects. Do check this to see if the impaired smell is one of the medicine's side effect.

On A Final Note...

People with hyposmia need to be careful about the safety aspects of their surroundings. Installing and maintaining carbon monoxide and smoke alarms at home can help in protecting the people with this condition. Also, people should be cautious while using potentially toxic household chemicals. Always check the food expiration dates before using them.