Why do hospitals smell so bad

This is how olfactory disorders and olfactory hallucinations occur in COVID-19

Experts can now explain how olfactory disorders and olfactory hallucinations occur in COVID-19 patients. This is reported by the German Professional Association of Ear, Nose and Throat Doctors.

Although there are still many unanswered questions about COVID-19, some side effects of infection with SARS-CoV-2 have already been well documented. Around 85 percent of people with COVID-19 suffer from olfactory disorders, which can range from a reduced ability to smell, also known as hyposmia, to complete loss of smell, known as anosmia.

Damage to the olfactory epithelium

"The scientific studies available to date show that the loss of smell due to COVID-19 is due to damage to the olfactory epithelium," explains Dr. Dirk Heinrich, President of the ENT Professional Association, in a press release. This is also the cause of the olfactory hallucinations that occur. The human sense of smell is the result of a complex interaction between nose and brain, says Dr. Jan Löhler, Director of the Scientific Institute for Applied ENT Medicine (WIAHNO).

"We have around 30 million olfactory cells that are constantly renewing themselves and are located in an area of ​​a few square centimeters on the uppermost nasal concha at the base of the skull its other end provides direct access to the brain via the long, thin nerve process. The olfactory bulb lies between the receptor cells and the cerebral cortex. This protruding part of the brain is the synaptic switching point for odor perception. , explains Löhler.

This is how olfactory disorders occur in COVID-19

With a corona infection, the areas of the nose responsible for odor perception are affected, according to the ENT doctor: "As part of a COVID-19 infection, the cells of the olfactory epithelium and the olfactory bulb are attacked and damaged directly by the virus. This receptor failure The olfactory disorders described primarily occur in COVID-19 patients. "

A secondary involvement of central parts of the brain is also being discussed. As with other viral inflammations of the nasal mucous membranes, the damage to the olfactory epithelium is primarily responsible for the olfactory disorder, emphasizes the WIAHNO director.

Smell hallucinations can also occur

The occurrence of olfactory hallucinations, which are repeatedly reported in the course of the coronavirus infection, can also be explained on this basis, continues Löhler: "Humans can distinguish around 10,000 scents. All naturally occurring scents are Specific fragrance mixtures with characteristic guiding fragrances. Seven fragrance classes are used for clinical differentiation, from floral and ethereal to sweaty and putrid. " In the course of recovery after a viral infection of the upper airways, partial regeneration of the olfactory epithelium can sometimes occur, which is accompanied by faulty olfactory perception, according to ENT doctor Löhler.

"If the regeneration of the sense of smell is incomplete, information from complex smells is only incompletely transmitted to the brain. Because certain fragrance components are missing, it is possible that, for example, in a roasted piece of meat, only the tarry component is perceived, which is also present , interpreted as sweet, but can no longer be smelled. " Since, in the worst case, only parts of a complex fragrance that are assessed as unpleasant are perceived, normally pleasant smells can be perceived as extremely unpleasant.

Photo: Adobe Stock / hans12

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