HYPOSMIA: CHARACTERISTICS, CAUSES AND TREATMENTS - GEOGRAFÍA - 2025

The hyposmia is a specific disorder of the sense of smell. Specifically, this alteration is characterized by causing a partial reduction in the ability to perceive odors. People who suffer from this alteration have their ability to smell and perceive fragrances reduced.

Hyposmia differs from anosmia by the preservation of certain abilities to smell. While the reduction in smell in hyposmia is only partial, in anosmia it becomes complete and the subject completely loses his ability to smell.

The causes that can cause this alteration are quite varied, but most of them are related to injuries or alterations in the nasal regions or in the brain structures that transmit the sense of smell.

General characteristics of hyposmia

Hyposmia is a type of olfactory disorder that causes a reduction in the person's ability to smell. Contrary to what it may seem, olfactory disorders are quite common and significantly affect the quality of life of individuals.

In this way, although hyposmia is not a highly dangerous or deteriorating pathology, it constitutes an important alteration that can significantly affect the life of the person who suffers from it.

In general, olfactory disorders can be due to rare congenital disorders, neurodegenerative or autoimmune diseases, head trauma, exposure to toxins, viral diseases, and rhinosinus inflammations.

In recent years, scientific interest in this type of disorder has increased notably, a fact that has allowed a greater scope of information about its causes, prevalences and therapeutic interventions.

Evaluation

The main element that must be evaluated for the diagnosis of hyposmia is the person's olfactory capacity. That is, what odorous stimuli is it capable of perceiving and what is the quality and intensity of said perception.

Currently there are no specific standardized tests for the evaluation of olfactory disorders. However, there is a series of validated tests that allow evaluating the identification of odors and the olfactory detection threshold.

In this regard, the most frequently used tool is the University of Pennsylvania Odor Identification Test. This instrument consists of 40 samples to scratch and smell. The patient must identify the odor among four options available for each of the samples.

Likewise, another evaluative technique that is usually used consists of identifying the olfactory threshold through the use of diluted vials. This method is longer and requires some training.

Consequences

The loss of olfactory capacity caused by hyposmia can cause a series of negative consequences for the individual's health.

Specifically, this alteration has been related to eating disorders, since the smell of food is disturbed, a fact that can cause a notable loss of interest in eating.

Likewise, the loss of smell can be a risk factor for health, since it limits the ability to detect spoiled food.

Finally, beyond the direct consequences on health, the loss of smell causes a significant reduction in the quality of life, since the individual sees limited one of their main senses of perception.

Causes

Research on hyposmia has increased notably in recent years, a fact that has made it possible to identify several factors related to its development.

At present, it has been shown that hyposmia does not respond to a single cause, but that several pathologies can cause this alteration. The ones that seem to be the most important are:

Allergies

Allergies are one of the most common causes of complete or partial odor loss. In fact, suffering from this pathology directly alters the nasal regions, and they tend to produce hyposmia in most cases.

Sometimes, if the allergy is properly treated, the individual can gradually recover their ability to recognize and perceive odors. However, in some cases the sense of smell gradually and permanently diminishes.

Head trauma

The alterations that cause a loss of olfactory perception need not always affect the nasal regions. They can also affect the brain structures that are responsible for transmitting the sense of smell.

In this sense, some cases of head trauma have been described that have caused total or partial loss of the sense of smell. The recovery of the olfactory capacity, in these cases, depends on the magnitude and severity of the trauma.

Nasal polyps

Nasal polyps damage the regions of the nose and often cause a marked reduction in olfactory ability. These damages can become permanent although the sense of smell usually recovers after the surgical removal of polyps.

Viral infections

Infections can also cause temporary or permanent hyposmia. Usually, the sense of smell is reduced only for the duration of the infection, and it usually recovers when it is treated properly.

However, in some minority cases, viral infections can cause a total loss of the sense of smell.

Treatment

In many cases, hyposmia does not require specific treatment, since the reduction in olfactory capacity can be temporary and disappear completely when the alteration that originates it is reversed.

Even so, in order to treat hyposmia, it is vitally important to make an adequate diagnosis and detect the factors related to its appearance. Once detected, the following treatments can be used:

Pharmacotherapy

If the hyposmia is due to an allergy problem or a vitamin deficiency, antihistamines can be administered to achieve recovery. In these cases, it is also important that the subject avoid the use of nasal decongestants, which can be counterproductive.

Surgical treatment

When hyposmia is caused by an obstruction or injury to the nasal passages, it is usually necessary to perform a surgical intervention to correct the problem.

References

1. Downey, LL, Jacobs, JB and Lebowitz, RA: Anosmia and chronic sinus disease. Otolaryngol Head Neck Surg 1996; 115: 24–28.
2. Factor, Stewart A., & Weiner, William J., eds. (2008) Parkinson's Disease: Diagnosis and Clinical Management, 2nd ed., Pp. 72-73. New York: Demos Medical Publishing.
3. Finelli PF & Mair RG Disturbances of Taste and smell, in (eds) Bradley et al, Neurology in Clinical Practice, 3rd Ed. 2000, Boston Butterworth Heinemann, p.263-7.
4. Leopold D. Disorders of olfactory perception: diagnosis and treatment. In Chem. Senses 2002 Sep; 27 (7): 611-5.
5. Yamagishi, M., Hasegawa, S. and Nakano, Y.: Examination and classification of human olfactory mucosa in patients with clinical olfactory disturbances. Arch Otorhinolaryngol 1988; 1245 (5): 316–320