Loss of taste and smell among hospitalised COVID patients

Thursday December 10th 2020

Almost two-thirds of people admitted to an Italian hospital with COVID-19 at the beginning of the pandemic had lost their senses of smell and taste, according to a small study published yesterday.

Study author Dr Francesco Bax, of Santa Maria della Misericordia University Hospital in Udine, said the findings suggest that doctors should consider the loss of taste and smell as early indicators of COVID-19 infection.

The research, published online in Neurology Clinical Practice, also revealed that about 22% of the 93 patients involved said impaired sense of smell and taste was their first symptom of infection.

“Loss of smell and taste are common in people who have COVID-19 infections, and our study found that these symptoms often occur before other symptoms, like fever or shortness of breath,” said Dr Bax.

“Because of that, clinicians should consider a patient’s loss of smell and taste an early indication of infection, one that is monitored closely while keeping that patient isolated, and possibly quarantined, until a definitive diagnosis can be made.

“While many people show evidence of COVID-19 infection in the lungs, we found there could be more at play than what a person’s lungs can tell us.”

The 93 participants had an average age of 63 and were admitted to the non-intensive COVID-19 unit of the hospital in March 2020 after either testing positive for the virus with a swab test or showing signs of lung problems with a chest X-ray or scan.

Loss of smell and taste were present in 58 people (63%) and for 13 (22%) of the participants those were their first symptom. The symptoms lasted for about 25-30 days.

When the researchers examined blood work, to see if there were certain biomarkers of inflammation, they found that compared to coronavirus-infected patients who did not lose their sense of smell and taste, those with compromised sense of smell had fewer leukocytes – particularly reduced neutrophils.

The people who lost their sense of smell had an average of 4,695 leukocytes per microlitre (μL), compared to 6,010/μL in those with a normal sense of smell – a 23% reduction – while those who lost their sense of smell had an average of 3,250 neutrophils/μL, compared to an average of 3,960/μL in those with a normal sense of smell – a decrease of 29%.

“More research is needed to determine whether this decrease in white blood cells we observed can be used to help identify patients in the early stages of COVID-19 infection,” said Dr Bax.

“For people whose first symptoms were loss of taste and smell, we found very few had nasal congestion, so we think obstruction of the nasal passages is an unlikely cause of these symptoms. However, the association between a blood cell imbalance and losing your sense of smell may help in identifying patients at risk.”

An American study in the same edition of Neurology® Clinical Practice warns that people who have a moderate case of COVID-19 could suffer neurologic complications including stroke, seizures, movement disorders, inflammatory diseases.

The study involved 74 people, whose average age was 64 and who tested positive for COVID-19 between 15 April and 1 July 2020. They were evaluated for various neurologic conditions at a large hospital in Boston, Mass., and 47 had prior history of neurologic disease.

At the time they were admitted to hospital, 18 people had strokes, 15 had seizures and 26 had a type of brain dysfunction that causes confusion and delirium. Seven people had movement disorders, including five people with myoclonus, while three had traumatic brain injuries due to falls in their homes after developing COVID-19.

One person had signs of developing autoimmune encephalitis, but these symptoms improved after the patient received corticosteroids.

Ten people died in the hospital, while those who survived had, on average, moderately severe disability, when they left the hospital, compared to mild disability before their hospitalisation.

Twenty-seven returned home and 20 went to nursing facilities, including 11 who had previously been living at home. Nine went to acute rehabilitation centres – eight of whom had previously lived at home.

Three people went to long-term acute care hospitals and five were entered into a hospice, either at home or as an inpatient.

Study author Dr Pria Anand, of Boston University School of Medicine, USA, said: “More research is needed to fully understand the breadth of neurologic complications associated with COVID-19 infection.”

Neurology Clinical Practice 9 December 2020

Tags: Brain & Neurology | Europe | Flu & Viruses

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