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Introduction

L"anosmia it is a disorder that consists in the loss of the ability to smell (sense of smell or smell). Depending on the causes that have determined it, it can be temporary, and heal following treatment, or it may not react to treatment and become permanent. However, it is rare that it is a disorder (symptom) associated with a serious problem.

The nose is the organ that intercepts odors (olfactory signals) which are then transmitted to the brain via the olfactory nerve. It is also the gateway for the oxygen contained in the breathed air. However, microorganisms also pass through it which they can cause infections of the nose, throat, lungs (rhinitis, pharyngitis, laryngitis, pneumonia and bronchopneumonia).

It is important that the nose is always kept clean and free, i.e. without obstructions. In fact, anosmia is often caused by a nose full of secretions or blocked by formations called polyps nasal.

More rarely, anosmia is linked to other causes affecting the central nervous system (head trauma, degenerative diseases such as Alzheimer's dementia or Parkinson's disease) or rare genetic diseases (Kallmann syndrome and Isolated Congenital Anosmia). Other causes known are: occupational exposure to toxic substances, harmful effects of some drugs and tobacco smoke.

It is difficult to ascertain (diagnose) anosmia because often the person who suffers from it does not notice the problems or judges the discomfort to be not serious and, consequently, does not go to the doctor to be examined.For this reason, there is no official estimate of the number of anosmia cases in the population.

If the sense of smell does not return to normal in a few weeks, it is necessary to go to the treating doctor to be examined. The doctor will try to find out the cause of the disorder and, if necessary, will prescribe a visit to the specialist doctor, the otolaryngologist.

Symptoms

The main disturbance (symptom) of anosmia is the inability to smell and concerns not only the smell of food but also those present in the environment in which one lives. This can pose a health risk as certain odors are useful in identifying hazards: for example, the smell of burning from a fire or from a saucepan left on a fire, or the smell of gas from a leak.

Furthermore, when the perception of odors (sense of smell) does not work, the sense of taste is also affected: the flavors of the food could be so different from usual as to cause a lack of pleasure in eating and, as a consequence, weight loss. excessive, malnutrition and even depression.

The disorders (symptoms) of anosmia are divided into:

  • loss of smell (anosmia)
  • perception of odors that do not exist (phantosmia)
  • decreased sense of smell (hyposmia)
  • perception of odors other than normal (parosmia)

Disorders can be:

  • transient, last for a short time and return to normal after treatment
  • chronic, persist even after treatment

Anosmia should not be confused with the common loss of sense of smell that occurs with advancing age.

Diagnosis

In order to ascertain (diagnose) the loss of the ability to smell (anosmia), the general practitioner (or otolaryngologist) inquires about the complaints (symptoms) that the person complains and about his state of health.Then he performs the medical examination to check whether neurological disorders are present or not: for example, memory problems, double vision (diplopia), difficulty in "swallowing food (swallowing), speech difficulties, etc. inspection of the nose to check for any obstructions or infections. It is possible that you also perform a test on smell (smell) by placing substances with a well-known odor, such as coffee, near the nose.

There are several tools on the market to evaluate the sense of smell: it is possible to test the intensity at which a certain odor is perceived (the olfactory threshold) and the ability to recognize odors, both by means of sniffin-stick (smell tests which consist in the presentation of strips of paper in which specific odorous substances have been included), both by means of cardboard scratch and smell impregnated with different odors (UPSIT test).

If the causes of the anosmia are not clear, investigations such as CT scans or magnetic resonance imaging of the head (which can also study the sinuses, cavities around the nose) to check for any structural lesions (a tumor mass, a fracture, an abscess, etc.).

Other instrumental olfactometry investigations that can be used to ascertain anosmia are the rhinomanometry, the electro-olfactogram and i olfactory evoked potentials called ERO (from the English evoked response olfactometry) or (O) ERP, which represent a valid method to evaluate the capacity of the olfactory system in an objective and quantitative way through a tool called olfactometer. With olfactometry we therefore mean an examination which consists in the use of a kit for the standardized presentation of odorants, at various concentration levels.The OERP allow to measure the response to the olfactory stimulus with a "reliability comparable to that of visual and auditory stimuli.

Causes

Loss of the ability to smell (smell) is most often caused by:

  • cold or flu
  • sinus infection (sinusitis)
  • allergy, such as hay fever and seasonal allergic rhinitis
  • growth of formations in the nose (nasal polyps)

more rarely it can depend on conditions affecting the brain such as:

  • head trauma
  • brain tumors
  • Alzheimer's dementia
  • Parkinson's disease
  • multiple sclerosis
  • viral brain infections and outcomes of neurosurgery

or it can be determined by drugs such as:

  • interferon alpha
  • different chemotherapy drugs, such as Cytosine arabinoside, Methotrexate
  • psychotropic drugs, such as Nifedipine in therapeutic dosages
  • prolonged use of local treatments based on silver salts, such as sulfadiazine-silver which is used for the local short and long-term treatment of burns
  • drug abuse

In addition, partial or total loss of smell is associated with some rare diseases such as:

  • isolated congenital anosmia
  • Kallmann syndrome, anosmia accompanied by incomplete development of the genital organs (hypogonadism) with absence of pubertal development and sexual maturity (puberty) in males

And to other causes such as:

  • use of tobacco, for smokers, particularly those with diabetes
  • occupational exposure to cadmium vapors, as in the case of workers involved in the production of alkaline batteries
  • aging, starting from the age of 60 can be one of the causes of irreversible hypo / anosmia
  • radiation exposure, associated with the treatment of head and neck cancers
  • psychiatric illnesses, such as schizophrenia

Therapy

The therapies for the disturbance of the perception of odors (anosmia) depend on the causes that have determined it.

If you have a sinus infection (sinusitis) or an allergy, it may help to clean the nasal passages thoroughly with a saline solution.

The saline solution can be purchased at the pharmacy or prepared at home. In this last case, a pot is prepared with half a liter of water (500 milliliters) to which a teaspoon of table salt (sodium chloride) is added, brought to a boil by dissolving the salt and then left to cool. After washing your hands, you stand in front of the sink and pour a little of the prepared saline solution into your cupped hand. At this point, a little saline solution is inhaled with one nostril at a time and then let it come out keeping the other nostril closed with a finger. Flushing can also be done using a 5-10-milliliter plastic syringe without a needle: fill the syringe with saline and slowly pour it into a nostril, allowing the liquid to drain. The washing is then repeated in the other nostril. It is not necessary to use all the saline solution, just a few applications in each nostril. The advanced saline solution must be thrown away and not reused.

In the case of infections, simply cleaning the nose may not be enough. In this case, it will be necessary to contact the doctor who can prescribe drugs such as:

  • antibiotics
  • cortisone

Once the infection is cured, the perception of odors (sense of smell) is almost always recovered.

If the cause is an obstruction of the nasal cavities, the ENT specialist will be able to check for the presence of simple inflammatory obstructions using the optical fiber nasal endoscopic technique (insertion into the nose of a small tube with a camera at one end). (such as rhinitis and sinusitis), anatomical irregularities (such as deviation of the nasal septum and hypertrophy of the turbinates) or the presence of formations, called nasal polyps, which do not allow the odorous particles to reach the upper area of ​​the nose where the sense of smell is located .

Once identified, obstructions are easily corrected with medical or surgical therapies that will allow you to regain the ability to smell.

If the cause of the anosmia is a tumor, the therapy consists of its surgical removal and radiotherapy. In this case it is unlikely that the sense of smell can be recovered.

In some cases, re-education treatment may also help (training) to the recognition of odors.

Prevention

Anosmia appears more frequently following an infectious or allergic cold but if the disorder (symptom) occurs suddenly, or without an apparent cause, or if you have had a recent head injury, it is important to consult an otolaryngologist to understand the cause.

Living with

According to some research, anosmia exposes you to a greater risk of domestic accidents and, in the most sensitive people, can contribute to the development of depressive disorders (symptoms) or eating disorders.

Furthermore, the loss of the ability to smell (smell) can lead to social isolation. Some of the people who suffer from it tend to develop the fear of giving off bad smell or having a dirty house by giving up the life of a relationship.

Other risks associated with anosmia consist in the unconscious consumption of spoiled foods, in the inability to detect gas leaks or the smell of burning. In these cases, the presence of gas detectors and fire alarms is essential. Many people also give up. cooking because not perceiving the smells they no longer consider it a pleasure.

Bibliography

NHS. Lost or changed sense of smell (English)

Italian Diagnostic Center (CDI). Can't you smell the smells? It is anosmia. Don't underestimate it

Humanitas Research Hospital. Anosmia

In-depth link

Orphanet. Isolated congenital anosmia

Orphanet. Kallmann syndrome

Telethon. Kallmann syndrome

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