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Although the loss of smell and taste became apparent symptoms of COVID-19 early in the pandemic, researchers are still investigating why this happens – the virus immediately infects and destroys the cells responsible for these critical sensations or is collateral damage from us. does the immune system fight the invading enemy? According to a posthumous study published this week in JAMA Neurology, it is the latest. The study – which fell deep into the noses, nerves and brains of 23 people who died of COVID-19 – is the most detailed look at the effects of the coronavirus on our sniffer. The researchers concluded that inflammation – not the virus – is behind the loss of smell and taste during a period of COVID-19, which is somehow good news. It suggests that treatments with anti-inflammatory drugs could prevent serious or long-term damage to these critical senses. The finding follows a mix of data on the effects of SARS-CoV-2 on our sense of smell. Some data suggest that the virus can infect the nerves that carry odor signals to our brain – the olfactory neurons. Thus, lost consciousness could be caused by direct infections. But others found that the virus was not present in these neurons at death. For the new study, researchers led by Johns Hopkins University physician Cheng-Ying Ho carefully examined the olfactory tissue of 23 patients who died of COVID-19 – nine of whom had lost all or part of their sense of smell and taste. In particular, the researchers looked at the olfactory neurons in the nasal mucosa, blood vessels and the number of olfactory axons – which are parts of neurons that transmit electrical signals – to each patient. They also examined injuries to the olfactory bulb, the part of the brain where olfactory signals are received, and determined whether or not SARS-CoV-2 was present. Advertising
They compared the findings with those of 14 people who died of other causes and had not been infected with COVID-19 and had no loss of smell or taste.

Following the aroma

Compared to controls and patients with COVID-19 without altered sense of smell and taste, patients with COVID-19 who had impaired sense of smell and taste had more injury to their nasal mucosa, more damage to their blood vessels, and significantly less olfactory nerves. However, this damage to the olfactory tissue was not associated with the documented severity of COVID-19 infections in patients – some people who had mild COVID-19 infections had serious injuries to their olfactory bulbs, for example. In addition, only three of the 23 patients had detectable levels of SARS-CoV-2 genetic material in their olfactory bulbs. Of these three, only one had reported olfactory loss. The other two reported no loss of taste or smell. These results suggest that “olfactory pathology was not caused by direct viral injury,” the authors concluded. “Previous research based solely on routine tissue tests — rather than in-depth and extremely detailed analyzes – has suggested that viral infection of the olfactory neurons and olfactory bulb may play a role in COID-associated olfactory loss 19. . “But our findings suggest that infection of the olfactory epithelium by SARS-CoV-2 leads to inflammation, which in turn damages neurons, reducing the number of axes available to send signals,” Ho said in a statement. in the brain and causes the olfactory bulb to malfunction ”. This malfunction can be so severe that the loss of smell and taste can persist for long periods of time or cause permanent damage. But in an audio interview, Ho noted, “If inflammation is the main cause of injury to the olfactory structures, it is possible that we can use anti-inflammatory agent as a treatment,” she said. “This I hope our study can inspire – future studies to look at this.”