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Loss of Smell and Taste Part of Screening for COVID-19

Reporter: Irina Robu, PhD

While brewing your morning coffee, you suddenly realize that you can’t smell the freshly ground beans, could you have COVID-19?

Doctors around the world began sharing reports of smell and taste loss in April 2020 in patients with confirmed cased of COVID-19. They suggested that these could serve as an early sign of infection, signaling people to self-quarantine before they develop a cough or fever. It is well known, that a variety of viruses can attack the cranial nerves related to smell that surrounds those nerves.

COVID-19 is known to cause inflammation, either directly around the nerve in the nasal lining and/or within the nerve itself. When the nerve is either surrounded by inflammatory molecules or has a lot of inflammation within the nerve cell body, it cannot function correctly. Even though it may not affect every patient with COVID-19, loss of smell and taste is certainly associated with the disease and in some countries such as France is used as a triage mechanism.

Dr. Zara Patel, Stanford professor of otolaryngology conducted a control study to compare the incidence of cranial neuropathies in two patients’ groups looking at family of neurologic disease such as Alzheimer’s disease, Parkinson’s disease and stroke. Ninety-one patients had post-viral olfactory loss and 100 were controls; and they were matched as closely as possible for age and gender. Patients with olfactory loss had six-times higher odds of having other cranial neuropathies than the control group — with an incidence rate of other cranial nerve deficits of 11% and 2%, respectively. Family history of neurologic diseases was associated with more than two-fold greater odds of having a cranial nerve deficit. Although we had a small sample size, the striking difference between the groups implies that it is worthwhile to research this with a larger population.

Their results show that patients may have inherent vulnerabilities to neural damage or decreased ability of nerve recovery beyond risk factors such as age, body mass index and the duration of the loss before intervention. When a patient has a viral-induced inflammation of the nerve, doctors treat it with steroids to decrease the inflammation. But then again treating COVID-19 patients with steroids might be a bad idea since of its effect on the inflammatory processes going on in their heart and lungs. However, it is up to the doctor treating the patient to decide whether the patient needs to be tested for COVID-19 or self-isolate to circumvent being a vector of the virus.

SOURCE

https://www.medscape.com/viewarticle/929116