A team of scientists from Thomas Jefferson Hospitalfrom Pennsylvania, was able to cure for the first time loss of smell due to COVID-19 in patients who continue to experience these symptoms many months or even years after the infection has resolved.
Data on smell loss due to COVID-19 has varied widely since the start of the pandemic. In 2020, a study conducted in China was published which showed that 5.1% of patients hospitalized with pneumonia caused by the SARS-CoV-2 virus, had anosmia among its symptoms. Later, when new variants appeared, there was talk of lower or higher percentages. Some more recent studies even indicate that up to 60% of infected patients are affected. But the truth is that, no matter how common the loss of smell is in each variant, it is still one of the symptoms that lasts the longest in Long COVID.
In fact, it is assumed that 5.6% of patients retains loss of smell due to COVID-19 for at least 6 months after infection. During all this time, many scientists have studied the origin of this anosmia associated with Long COVID. And they found some clues, but not enough to design effective treatment. Fortunately, these scientists’ proposal, the results of which will be presented at the annual meeting of the Radiological Society of North America, is the first to offer hope, since a very high percentage of patients in their studies said goodbye to anosmia.
What causes loss of smell due to COVID-19?
The SARS-CoV-2 virus, which causes COVID-19, enters the cells it infects through receptors known as ACE-2which he communicates with through his spike proteins, which act like a key in a lock.
This occurs in the cells of many body systems, which is why the symptoms of the disease are so varied. But there are some in which he is particularly skilled. For example, it has been proven that proteins thorns They pair perfectly with ACE-2 receptors on brain cells. olfactory epithelium. This is the tissue that lines the nasal passages and contains three types of cells: basal cells, olfactory sensory neurons, and supporting cells.
The latter have very strong expression of genes encoding ACE-2. So not only do they have instructions for assembling these receivers, but they use them in abundance. Many receptors are synthesized. And not only this. Expression Genes encoding TMPRSS2a protein needed so that once the key is attached to the lock, the virus can finish entering the cell.
This indicates widespread infection by SARS-CoV-2. supporting cells olfactory epithelium. After this, it is only a matter of time before the damage is transferred to the sensory neurons responsible for transmitting information to the brain. olfactory signals.
This is how loss of smell occurs due to COVID-19. But anosmia is not the only odor-related symptom. There are also patients who experience phantosmiasymptom characterized by detection unpleasant odors which actually don’t exist.
Stellate ganglion as the protagonist of a new treatment
Transmission of signals from the senses is part of the functions autonomic nervous system. That is, something that we cannot voluntarily control. We have no control over what we smell. The smells just reach us. Just like sounds, tastes, what we see and what we touch.
The autonomic nervous system consists of sympathetic and parasympathetic and this is one component of the first one that appears to be the key to treating smell loss due to COVID-19: stellate ganglion.
Formed by the fusion of the inferior cervical and first thoracic ganglia, this structure is responsible for sympathetic innervation face, neck, upper limbs, heart and lungs.
This ganglion is often blocked with an injection of an anesthetic to treat many types of pain. But the authors of the new study believe this blocking could have more uses. TO administer anesthetic, signals traveling along this path are blocked. But at the same time, the regional autonomic nervous system is stimulated.
New hope for persistent COVID patients
To work on this hypothesis, the study authors recruited 54 patients with loss of smell due to COVID-19 for at least 6 months. This time is enough for them to be considered as having recovered from COVID.
They all underwent a very simple intervention, just 10 minutes duration. Initially using the manual CT scanA spinal needle was placed at the base of the neck. Later this was used to administer an anesthetic, to which was also added a small dose of corticosteroid. It is unusual for the stellate ganglion to be blocked. However, in this case, since they suspected that the virus might have caused the nerve inflammation, they thought it might be a good option. So it was.
Follow-up was completed in 37 patients (65%), of whom 22 (59%) reported improvement in symptoms one week after injection. Of these 22, 18 (82%) reported significant gradual improvement one month after the procedure. Three months later he appeared The mean improvement in symptoms among the 22 patients was 49%.
On the other hand, it is worth noting that 26 patients returned for a second injection at other side of neck after a break of at least six weeks. Although the second injection was not effective in patients who did not respond to the first injection, 86% of those who reported some improvement after the first injection reported further improvement after the contralateral injection.
Finally, something very positive is that no side effects were reported. This is great news. And a definitive cure for persistent COVID may not have been found yet, but at least doctors now have a cure for one of its most common symptoms. Having a sense of smell again will be a blessing for these patients.
Source: Hiper Textual
