Anosmia (loss of smell): symptoms, causes and treatment

This otorhinolaryngological disease can have various causes and ways of expressing itself in symptoms.

Losing a sense is always a cause of significant discomfort and difficulties in daily life. People who suffer from blindness or deafness need certain aids to be able to carry out their lives to the full, but not without encountering obstacles along the way.

However, losing the sense of taste or touch also often has a very negative impact on people.

In this article we are going to talk about the loss of the ability to smell, i.e. anosmia.. This little-known disability is not something that should be considered as insignificant, as it can even pose a threat to the person affected by this condition.

What is anosmia?

Anosmia is the inability to perceive odor, or it can also be a significant decrease in the ability to smell. the significant decrease of the olfactory capacity.

This problem can have a variable duration, being in many cases something temporary, due to a cold or a passing problem in the respiratory tract. In other cases, the cause may be more serious and cause permanent anosmia, such as a genetic factor and having suffered an accident with brain involvement, especially if the brain structures responsible for the sense of smell have been damaged.

Thus, the cause of this problem can be in the nasal passages as well as in the nerves and the brain. This can result in different types of anosmiaaffecting the ability to smell from one or both nostrils. When only one nostril is unable to smell in one nostril we speak of unilateral anosmia.

Terms related to anosmia are hyposmia, which is a decrease in the ability to smell, and hyperosmia, which is when you smell more intensely. It may be the case that you are anosmic only for certain types of odors. When anosmia is present from birth, it is called congenital anosmia.

How do we smell?

To better understand how anosmia can occur, we must first understand how our sense of smell works. Smell is the sensation resulting from inhaling particles that attach to receptors in the mucous membranes of the nose. These receptors are located in the yellow pituitary gland. The receptors are capable of detecting up to seven essential odors: ethereal, musky, floral, menthol, spicy, camphoraceous and putrid. The combination of these allows up to 10,000 different fragrances to be perceived..

When the receptor is stimulated, a nerve impulse is sent through the olfactory nerve (first cranial nerve) which carries the information to the olfactory bulb. From there, the information goes to the hypothalamus and then to the cerebral cortex where the odor becomes conscious.

If the nasal mucosa, nerves or brain structures involved in odor perception have been damaged, anosmia can occur in different degrees and with different treatment options, in case it is possible to remedy it. if remediation is possible.

Associated symptoms

The main symptom by which anosmia is identified is the absence of the perception of olfactory stimuli. The way in which this loss of the ability to smell occurs can take many forms, either abruptly and insidiously or progressively.

The ability to detect odors is not as highly developed in humans as in other species; however, it has evolutionary purposes and its loss entails disadvantages that affect the daily life of anosmic people.

Food spoilage, gas leaks and fires are situations that can be identified by odor.. For this reason, not being able to detect them is a real risk for the person, since he or she is unknowingly exposed to a potentially deadly threat.

People who have lost the ability to sense smell in an acquired form lose their appetite, since they cannot perceive a stimulus inherent to food that makes it attractive, such as its good smell. This can lead to excessive weight loss and malnutrition.

In addition, in cases in which this problem presents itself in an acquired form, there are depressive symptomatology.This is due to the fact that olfactory stimuli associated with emotional memories can no longer be felt, which makes the person feel that he or she has lost part of his or her capacity to remember. In addition, loss of libido may occur due to not detecting sexually arousing odors.

Possible causes

There are multiple causes that may be behind the onset of anosmia, in addition to being able to affect different structures involved in the sense of smell. Temporary loss of the ability to smell may be due to infectious and inflammatory problems, such as colds, allergic reactionssuch as colds, allergic reactions, acute sinusitis, hay fever, flu, polyps, tumors and bone deformities inside the nose.

In cases where this medical condition is severe and permanent, it may be caused by having suffered a craniocerebral accident that has damaged brain structures or having inherited this problem. Anosmia is associated with normal aging and also occurs in early stages of dementias.

It can be a symptom in Alzheimer's, Huntington's, Parkinson's and Niemann-Pick disease, as well as appearing in multiple system atrophy, schizophrenia, Korsakov's syndrome and other severe disorders. It can also be a consequence of some problems at brain level may be behind suffering from anosmia: brain surgery, aneurysms, traumatic brain injuries...

Kallman syndrome is the most common cause of congenital anosmia.. In this case, it could be due to a lack of olfactory epithelium in the embryogenesis of the olfactory placode, which is replaced by respiratory epithelium in the abnormal development of the embryo.

The abuse of nasal sprays can affect the nasal mucosa, both nasal vasoconstriction sprays and those used as a symptomatic remedy for some forms of allergy. Although its occasional use does not pose a risk, its abuse should be avoided and, in case of long-lasting nasal inflammation, a professional should be consulted to evaluate other options. Nasal surgery, such as rhinoplasty, may also cause this problem. Exposure to certain chemicals, such as insecticides and solvents, as well as zinc deficiency.in addition to suffering from zinc deficiency has been associated with the appearance of anosmia.

Diagnosis

In order to find out if a person may be suffering from anosmia, it is necessary to carry out an interview, since, although it may seem surprising, there are anosmic people who do not know that they suffer from this problem, especially if they have it congenitally.

To detect this problem acetylcysteine tests are used. The person is also asked if he/she has suffered any type of injury or if he/she has abused certain substances that are introduced through the nose. In addition, you will be asked if you have had any respiratory problems, especially in the nose. An examination of the inside of the nostrils is performed using a rhinoscope.

Thus, a neurological evaluation is performed to see if any nerves have been damaged after an accident. More common than you might think are cases of people who have been involved in car or other accidents who have begun to suffer symptoms of unilateral anosmia.

It is common for cases of congenital anosmia to go undetected, mainly because the person has never smelled the symptoms of unilateral anosmia.mainly because the person has never smelled in his life and, therefore, does not have the experience of what is the sense of smell.

Treatment

Depending on the cause of the anosmia, there will be different treatments. Anosmia due to brain damage is hardly treatable, but anosmia caused by inflammation of the nasal mucous membranes can be treated.. In this second case, glucocorticoids, antihistamines, anti-inflammatory drugs and Antibiotics are used.

On the other hand, anosmia caused by nasal obstruction or the appearance of polyps and tumors will require surgical intervention. Certain losses of the ability to smell are due to nutritional deficiencies, such as lack of zinc, and are corrected by providing the deficient substance.

Bibliographical references:

• Ropper A. H., Brown R. H. (2007). Disorders of smell and taste. In: Ropper A. H., Brown R. H. (Eds). Principles of Neurology, (195-202). Mexico: McGraw-Hill Interamericana.
• Soler G. M. (2002). Congenital anosmia: review and clinical cases. Federación Argentina de Sociedades de Otorrinolaringología, 1: 55-60.