When we hear the phrase, “loss of sense of smell,” our mind might (reasonably) jump to COVID-19. That neurological symptom is fairly common among patients who contract the virus responsible for our latest pandemic.

But your patients may not know that there’s a word for this symptom. Anosmia, or the inability to perceive odor, is also associated with influenza, allergies, and other conditions. Doctors can help patients manage anosmia with medication and surgeries, as needed.

 

Loss of senses

In addition to affecting patients with COVID-19, anosmia can show up in patients who have colds, flus, allergies, polyps, and other conditions. While temporary anosmia can affect people of all ages, individuals above the age of 50 are more likely to experience long-lasting anosmia.

According to an article published by StatPearls, anosmia can be temporary, or stick around for the duration of a patient’s life.

Li X, Lui F. Anosmia. StatPearls. Updated July 4, 2022.

A symptom that can be acquired or congenital, anosmia has a variety of causes.

 

For example, when a patient suffers a disturbance in the sensory nerves related to the olfactory bulb—or anywhere in the transference of a smell to the brain—anosmia can arise. Patients can also lose their sense of smell as a result of a physical blockage along the physiological route an odor takes to reach the brain.

The authors of the StatPearls article elaborated, writing, “Anosmia amongst patients can have safety implications as those without the ability to smell might miss important warning odors such as smoke from a fire or natural gas leaks.”

Thus, addressing anosmia in patients is a health and safety concern that requires further exploration of potential root causes.

 

How COVID-19 can cause anosmia

In terms of COVID-19-related anosmia, emerging evidence paints a clearer picture of the neurological processes behind it.

A 2022 study published by Cell concluded that human patients and hamsters with COVID-19 who have anosmia tend to experience a non-cell-autonomous, sweeping downregulation of olfactory receptors (ORs) and genes that signal to ORs.

Zazhytska M, Kodra A, Hoagland DA, et al. Non-cell-autonomous disruption of nuclear architecture as a potential cause of COVID-19-induced anosmia. Cell. 2022;185(6):1052–1064.e12.

 

This follows neuronal nuclear architectural reorganization, paving the way for certain genomic compartments containing OR genes to fall away. Thus, patients infected with COVID-19 whose olfactory functions have been compromised may lose their sense of smell.

 

Anosmia prevalence and diagnostics

Anosmia is a relatively common symptom for patients with COVID-19. But what percentage of the general population experiences a loss of smell at some point?

As noted by StatPearls, 3% of patients over the age of 40 struggle with anosmia. That percentage rises to 14%–22% of individuals over the age of 60. As patients age, the likelihood of losing the ability to perceive smell increases.

Doctors who think a patient may have anosmia can determine so by running a few smell tests using chocolate and coffee. If the patient struggles to identify a scent, the next step might be to send them for chemosensory and butanol threshold tests to determine how severe the anosmia is (or, how “much” of their sense of smell is gone).

If you believe your patient lost their sense of smell for a specific reason, test them for applicable underlying conditions such as head trauma, neoplasm, or sinus disease. MRIs and CTs may be utilized in this stage.

Allergists and ENTs play important roles in determining the cause of anosmia and may know how to direct the patient in terms of appropriate labs and tests to complete.

 

Treatment, management

According to an article published by the Cleveland Clinic, antibiotics for conditions like sinusitis usually do the trick.

Anosmia (loss of sense of smell). Cleveland Clinic. Updated September 29, 2021.

Patients who lose their sense of smell due to a specific medication, however, may switch to a different one.

 

In addition to medication-based treatments, patients who have polyps may need surgery to regain their sense of smell.

Because anosmia is most commonly caused by inflammatory and obstructive diseases, antihistamines, intranasal glucocorticoids, and systemic glucocorticoids are effective treatment options for patients with these conditions.

Establishing the root cause of your patient’s anosmia increases the chances of finding effective treatment and management methods—which hopefully bring your patient back to their senses.