CT Imaging Finds No Sinus Changes in COVID-19 Anosmia

By Marilynn Larkin

July 31, 2020

NEW YORK (Reuters Health) - No significant mucosal changes or olfactory cleft abnormalities were found in a computed tomography (CT) imaging study of the paranasal sinuses of COVID-19 patients in Iran.

As reported in the American Journal of Otolaryngology, Dr. Ayeh Taraghi of Masih Daneshvari Hospital in Tehran and colleagues assessed 49 COVID-19 patients (average age, 45; 45% men) presenting with anosmia between April 1-May 15.

The most common underlying disease was diabetes mellitus (26.5%). Complete anosmia was detected in 85.7% of patients, and in 91.8%, loss of smell was sudden. The time between COVID-19 onset and perception of olfactory dysfunction varied because of a general lack of attention given to that symptom. Taste disturbance was common (75.5%).

No significant pathological changes in the paranasal sinuses were detected on CT scans. Olfactory cleft and ethmoid sinuses appeared normal, while partial opacification of other sinuses was detected only in some cases.

The authors note, "Since there were no significant mucosal changes detected, utility of therapies such as steroids for treatment of anosmia in this group of patients is questionable"

Dr. Aria Jafari, Assistant Professor, Rhinology, Sinus and Endoscopic Skull Base Surgery at the University of Washington, Seattle, commented in an email to Reuters Health, "This study suggests that the smell loss...is a result of nerve damage, rather than swelling of the lining of the sinonasal tissues causing blocking odors from reaching the olfactory cleft (where smell is perceived). This is a somewhat surprising finding, as other studies have shown focal swelling in (this) area in COVID-19 patients with smell loss."

"We know that smell loss related to nerve damage takes much longer to recover than that related to swelling, so this distinction is important," he said. "Clinically, most patients with COVID-19-related smell loss appear to recover within two weeks, which suggests that symptoms recover as the swelling subsides, but it is still too early to know about more subtle long-term consequences."

Regarding steroid use, he noted that a majority of COVID-19 patients recover spontaneously, but if smell loss persists, "current research suggests that structured and repetitive sniffing of known odorants a few times per day, known as 'olfactory training,' can be an effective treatment."

His team's recently published review of that strategy found "olfactory training is a low-risk intervention that provides clinically relevant and sustained benefit beyond the observed rates of spontaneous recovery." https://onlinelibrary.wiley.com/doi/abs/10.1002/lary.28902?af=R

Dr. Manu Jain, a pulmonary and critical care specialist at Northwestern Medicine in Chicago, also commented in an email to Reuters Health. "Though the data are discrepant, it is likely that patients who have quick onset and recovery have local inflammation in the olfactory cleft which inhibits detection of smell by the olfactory nerve endings," he said. "Once the local inflammation resolves, smell returns relatively quickly. In patients who have slower recovery, it is likely that the inflammation actually damages the nerve (not just obstructing the signal) and it takes longer for the nerve to recover, on the order of weeks. It is possible that the nerve is damaged so severely that it may even take longer than that."

"Once there is an effective anti-viral for COVID that can be used as an outpatient (i.e., early in the course of illness), this may shorten the duration of anosmia," he concluded.

Dr. Taraghi did not respond to requests for a comment.

SOURCE: https://bit.ly/39Hixui American Journal of Otolaryngology, online July 3, 2020.

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