The disappearance of smell and taste left the Sevillian kitchen boy Miguel Ángel Barbas dislodged after being infected with the covid last winter. Only now does he begin to recognize certain smells. His routine is full of uncertainties. “At first it smelled absolutely nothing. Little by little, now I smell something. The most dangerous thing is the use of degreasers to clean pots and kettles, the vapors can affect me and I don’t know if a meal is burned or if there is a gas leak ”, he says uneasily. The total or partial loss of smell and taste is one of the most frequent persistent symptoms after being infected by coronavirus, and to alleviate it, the olfactory rehabilitation of patients has grown in parallel with the creation of specialized units in many hospitals. “The demand for care in patients with impaired smell has been exponential, an explosion since the COVID broke out,” says Ramón Moreno Luna, otolaryngologist at the Virgen de Macarena Hospital in Seville.
Half of the patients infected with coronavirus suffered an alteration of smell (53%) or taste (52%), according to a study in 15 Spanish hospitals. And experts say that up to 15% of affected patients can still not smell anything three months after being infected. To recover it, it is decisive to rehabilitate this sense, to help it to re-identify the odors lost due to the destruction suffered in the epithelium. “The meta-analyzes show that a covid patient who is rehabilitated is three times more likely to recover and does so faster than the rest,” illustrates Claudio Fragola, an otolaryngologist at the Ramón y Cajal Hospital who, like the Barcelona Clinic, it already had a smell unit before the pandemic.
Often the covid not only cancels the smell (anosmia), but also causes confusion in patients and it is difficult for them to associate what they smell with memory. It is not detection, but a distortion of the smell (parosmia): patients mistake the smell of a shampoo or cream for a sewage or rotten stench, or in front of a rose they smell like gasoline. Distortions that emotionally alter people, emphasizes Moreno Luna, who specializes in rhinology and skull base. Sometimes they do not smell the colony, but they do smell the alcohol of the colony, since they are smells identified with the risk system. Adriana Izquierdo, coordinator of the smell unit at the Terrassa Hospital (Barcelona) and member of the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (Seorl) explains that “there is an unpleasant but new smell”. “I call it covid odor. The patients describe it as if it were rotten meat, but they do not know how to detail it completely, ”he says.
The olfactory training equipment, which can be purchased in pharmacies and the Internet, includes bottles of oils with four essences –rose, lemon, clove and eucalyptus–, or in vaseline with six scents –lemon, rose, smoked, vinegar, anise and eucalyptus– . Some experts recommend the latter because the Mediterranean population does not easily recognize the smell of cloves, much more used in countries such as Pakistan or India. First, the patient looks at the picture of a lemon, the lemon sorbet, and the lemon cookie; then smell the corresponding scent for 20 seconds, and so on with each scent. Rehabilitation is a routine process that takes 10 minutes in the morning and another 10 at night.
The typical patient with loss of smell due to covid is between 30 and 50 years old, suffers mild symptoms and goes to the specialist’s office after enduring more than three months of loss of consciousness. Alfonso Chacón, winemaker and owner of the Canopy wineries in Toledo, lost his sense of smell and taste, and little by little he revived it thanks to a home rehabilitation. “I made a recovery as a training and it took me three months to achieve it. I took things that I identified and had memorized, like a vanilla, vinegar, at first mild aromas of power and later characteristic smells nearby, to exercise. It’s my job, if I don’t taste the wines I don’t know how they are. I was worried about the level of loss it could cause me and how long, that made me anxious, “he says.
The cause of this phenomenon is that the coronavirus destroys the cells that in the olfactory epithelium give metabolic and structural support to the only neurons in the brain in direct contact with the outside – from 20 to 30 million. Smell will recover sooner or later depending on the structural damage and how long it takes for the regeneration of these neurons, highlights Laura López-Mascaraque, neuroscience researcher at the Cajal Institute of the CSIC and president of the Spanish Olfactory Network, an association to spread the word around the world. smell with researchers, winemakers, perfumers, engineers and experts in artificial intelligence. “These neurons have to find, again, their path to the brain,” says López-Mascaraque. “Smell, to which 3% of the genome is dedicated – almost 400 genes – is the only chemical sense next to taste, where odorant molecules are processed in the brain and interpreted as smells”, explains López-Mascaraque, who jokes with that the covid has brought anosmia to the vocabulary of the people in general.