Published online Sep 25, 2022. doi: 10.5501/wjv.v11.i5.362
Peer-review started: April 13, 2022
First decision: June 16, 2022
Revised: June 24, 2022
Accepted: August 12, 2022
Article in press: August 12, 2022
Published online: September 25, 2022
Processing time: 163 Days and 17.2 Hours
There are numerous conflicting discussions about the outbreak of the new coronavirus (COVID-19).
Describe the anatomy and physiology relationships of taste and smell losses due to COVID-19
To present some anatomical and physiological considerations about two of the symptoms reported by patients: the loss or reduction of smell and taste.
Since, these symptoms are presented in a peculiar way, with some cases of persistence even after COVID-19. For this, it was searched in three databases, PubMed/MEDLINE, Web of Science and Scopus, using the following keywords: "Smell", "Taste", "Smell AND COVID-19", "Taste AND COVID-19", no publication time restriction, only in English with full text available, excluding also brief communications, letters to the editor, editorials, reviews, comments and conference abstracts.
The search found 776 articles in the database PubMed/MEDLINE, 1018 in the Web of Science database, and 552 in the Scopus database, from which duplicates were removed (104 articles). Finally, 17 studies were selected for detailed analysis within the eligibility criteria, with titles and abstracts related to central nervous system lesions responsible for smell and taste. This review suggests that viral mechanisms of action may be related to lesions both at the local level and at the level of the central nervous system, lasting up to 3 to 4 wk. It is considered persistent if it exceeds this period, as reported in one case in this review. There are still few studies about the treatment, and among those addressed in this review, only two studies reported possible treatments and emphasized the scarcity of data, with the best option being treatments that do not cause harm, such as gustatory and olfactory physiotherapy
Most of the articles studied reported that possible anatomophysiological mechanisms related to the loss of smell and taste, are local lesions in the olfactory and gustatory tissue due to having ACE-2 receptors, with the SARS-CoV-2 gateway being the oral and nasal cavity. In addition to local lesions, there are central changes in the tissues of the nervous system related to taste and smell, which are also damaged by the neurotropic capacity of SARS-CoV-2. The duration, in most cases, can extend from 3 to 4 wk, and it is considered persistent after 1 mo. Therapeutic conducts in persistent cases with better initial results, which could be indicated by the doctor, are the use of steroid-based sprays and rinses and, mainly, the training of the senses of smell and taste. Likewise, the best measure to be taken is prevention, with the correct use of PPE by health professionals, and respect for local health recommendations determined in order to reduce viral spread.
Future studies should further describe the relationships between the anatomy and physiology of taste and smell losses due to COVID-19.