Elsevier

Journal of Clinical Neuroscience

Volume 93, November 2021, Pages 31-35
Journal of Clinical Neuroscience

Clinical study
Residual olfactory dysfunction in coronavirus disease 2019 patients after long term recovery

https://doi.org/10.1016/j.jocn.2021.07.050Get rights and content

Highlights

  • Olfactory disfunction identified with the Brief Smell Identification Test for Chinese and Hyposmia Rating Scale still existed in nearly one-third of COVID-19 patients after a 3 months recovery.

  • Olfactory function kept recovering continuously through a five-weeks follow up.

  • There’s a potential that olfactory impairment will last forever as an irreversible symptom in some COVID-19 patients.

Abstract

Introduction

Hyposmia is among the most common symptoms of COVID-19 patients. Previous research has mainly described this issue at the disease’s early stages. Because olfactory impairment can indicate neurological degeneration, we investigated the possibility of permanent olfactory damage by assessing hyposmia during the late recovery stage of COVID-19 patients.

Methods

Ninety-five patients were assessed with the Brief Smell Identification Test for Chinese (B-SITC) and Hyposmia Rating Scale (HRS) after 16 weeks from disease onset. Five weeks later, 41 patients were retested with B-SITC.

Results

At the first visit, hyposmia was identified in 26/82 (31.7%) and 22/95 (23.2%) of participants by HRS (HRS score ≤22) and B-SITC (B-SITC score <8), respectively. The rates of hyposmia in patients who performed B-SITC after 14–15 weeks, 16–17 weeks, and ≥18 weeks from disease onset were 7/25 (28%), 8/35 (23%) and 7/35 (20%), respectively, which demonstrated a trend of olfaction improvement as recovery time prolonging. Hyposmia percentages decreased from the first visit (34.1%) to the second visit (24.4%) for the 41 patients who completed 2 visits. B-SITC scores of the first-visit hyposmia participants increased significantly at the second visit (5.29 ± 2.02 to 8.29 ± 2.40; n = 14, P = 0.001). Severe cases tended to recover less than common cases.

Conclusions

Hyposmia was present in up to one-third of COVID-19 patients after about 3 months from disease onset. Notable recovery of olfactory function was observed at a next 5-weeks follow-up. Clinical severity had little influence on olfactory impairment and recovery.

Keywords

Hyposmia
COVID-19
Coronavirus
Objective smell test
Neurodegenerative disease

Cited by (0)

1

Co first author to: Yuanyuan Zhu and Ming Cao.

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