Loss of smell (or anosmia) is one of the most common and reliable symptoms among Covid-19 positive cases.
If the mechanisms of the loss of smell are certainly a little better known after two years of pandemic, there are still some gray areas, especially on this loss in the long term.
American researchers have closely analyzed certain organs taken from a cohort made up of 23 people who died of Covid-19 and a control group of 14 dead people, whose deaths were not linked to the virus.
Their conclusions are clear: patients with Covid-19 are more likely to have damaged blood vessels and axons, a nerve fiber that transmits electrical signals between neurons in the olfactory bulb, this region of the brain. which treats the sense of smell.
More damaged nerve fibers
In detail, the degeneration of these axons was 60% more serious and the microscopic blood vessels were 36% more serious in patients who died of Covid than in people who died without having contracted the virus.
This study is an important step in understanding the cases of anosmia in people with long Covid (around 340,000 people out of the 3 million French people affected by this disability). However, some questions remain unanswered.
In the study published this Monday in the scientific journal JAMA Neurologythe authors specified that the lesions caused in the olfactory bulb were not directly caused by the Covid, but that they could be the consequence of an inflammation caused by the virus in this same area.
Necessary olfactory rehabilitation
People suffering from anosmia several weeks or months after their infection can benefit from a consultation with an ENT specialist, then carry out olfactory rehabilitation. It is also advisable to smell on a daily basis, by sniffing your morning coffee or another familiar smell.
Experimental treatments are also carried out, such as the implantation of sponges soaked in plasma in the nose of anosmic patients.
Even if the effectiveness of this therapy remains to be proven, some have gradually regained their sense of smell. The most likely hypothesis for this gradual healing is that plasma helps rebuild damaged blood vessels.