Some stimulation exercises accelerate the rehabilitation of these senses, also affected in other diseases.
Anosmia, the complete loss of smell, and ageusia, the total loss of the ability to appreciate flavors, are among the most common symptoms suffered by people who contract coronavirus. It is a condition that can last a few days or several weeks, but in some cases it lasts much more in time. And not only Covid-19 causes the loss of smell and taste.
Before the pandemic, it was already known that respiratory viruses can negatively affect these two closely related senses. After having a very bad cold there are people who also temporarily lose the sensitivity of these senses, with a strong impact on quality of life of those affected.
And how can smell be restored? Are there therapies or rehabilitation exercises? How long does it usually take to get it back? Almost ten months after the first great wave of the pandemic, numerous studies validated by the international medical community have already been carried out with coronavirus patients who had lost their sense of smell. And they indicate that 45% of them recover their smell in two or three weeks at most, without major complications. But there are 7% of those affected who need more than three months.
The odor is detected by a seal-sized area of the nose called the epithelium, where odor receptors are located. Once the smell is captured through the nose, the cerebral cortex intervenes, in the area of the olfactory bulb, which interprets it. The so-called olfactory memory depends on this automatic mechanism.
Smell, the bodily sense with which aromas and substances dispersed in the air are perceived, was the first sense developed by animals. Recent studies show that humans are capable of discriminating a trillion odors and not 10,000 as was thought 100 years ago.
The olfactory bulb is near memory regions of the brain. It is not surprising, then, that smell is one of the senses most connected with lived experiences. Who did not mentally travel to a situation, a place or a person from our childhood after capturing a certain smell?
Studies carried out with positives for coronavirus conclude that the affectation largely depends on how the virus causes this loss of smell. The gateway is the nose: inhaling the virus causes a local inflammation making it difficult for odor particles to reach the roof of the nose.
There is a second mechanism, with an affectation that occurs directly in the olfactory membrane, in the olfactory bulb, which makes it difficult for the brain to discriminate and identify one smell from another.
When we smell, nerve endings pick up the smell, and the brain interprets it. There are supporting cells that help you smell. Covid-19 does not directly attack these nerve terminals, affects only these supporting cells.
“This is good and is what explains why most patients regain their sense of smell when the coronavirus passes, but when it affects neurons or the nervous system it costs more; it may take months to recover or sometimes it does not even recover “, warns Maria Foglia Fernández, director of the Otorhinolaryngology Service at the Sant Joan de Reus University Hospital.
If after three weeks, after overcoming the virus, the patient has not recovered his sense of smell, it is advisable to go to the specialist, the otolaryngologist, and raise a rehabilitation therapy. “Rehabilitation actions for the smell can be done, we have tools for that”, Foglia points out.
Normally a set of smells is used, with very common aromas, which are passed to the person so that they can smell them at different concentrations. In this way, “the rehabilitation time is shortened thanks to olfactory stimulation”, explains the doctor.
And he warns that it is necessary to watch out for excessively intense aromas, which can cause irritation, so it is advisable to always do it with the help of a doctor and not on your own.
The tools are similar to those used by professionals who rely on the olfactory sense, such as sommeliers or perfumers, who need to train to have a finer sense of smell. Although there are people who are better equipped, with more ease and olfactory sensitivity, the basis of a fine sense of smell is above all in the stimulation, in the work and the exercise that is practiced with this sense. Olfactory memory, which allows us to identify a certain smell, is based on daily work.
But it’s not just the coronavirus that causes loss of smell. Trauma can also cause it abruptly. A very strong direct blow to the nose or rebound, with a blow to the head that causes an injury to the cells that we need to perceive the smell.
There are other pathologies, such as allergies, that also cause a decrease or loss of smell. 40% of acute causes are caused by respiratory viruses. If the affectation is on the nerve cells, this is when it normally takes longer to recover the smell or even it is not possible to recover. “Loss without recovery is very rare, less than 10% of cases. In any case, the recovery depends on the severity of the loss, the place of the affectation and the age of the patient, “says the specialist.