Pathological Findings of Post-Viral Olfactory Dysfunction: A Systematic Review
Bibliographic record
Abstract
Abstract: The coronavirus disease 2019 pandemic has shed light on the post-viral olfactory dysfunction (PVOD). Post-viral olfactory dysfunction is temporary for most people and usually subsides when the common cold symptoms ameliorate. However, in some patients, this condition can persist for several weeks or months. The exact pathological mechanisms of persistent olfactory loss secondary to upper respiratory tract infection (URTI) is unknown, and there is a lack of efective treatment. An increased understanding of pathology could possibly translate into new therapeutic regimens. The aim of this systematic review is to synthesize primary data regarding histopathological and neuropathological fndings in patients with PVOD secondary to URTI. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was followed. Databases PubMed and Web of Science were searched with keywords and mesh terms to identify relevant articles. The quality of included studies was assessed with the Newcastle–Ottawa Scale for observational studies. The search yielded a total of 847 articles, after excluding duplicates and articles that were not relevant. A total of 12 studies were selected. The main fndings of this review were: olfactory bulb (OB) volume was decreased in patients with PVOD, there was a negative correlation between OB volume and duration of olfactory loss, both primary and secondary olfactory cortex changes were found in terms of structure and functionality, and the olfactory sensory neurons and nerve bundles were reduced in patients with PVOD. The mechanisms of PVOD are complex. This review found that viral URTI is attributable to structural and functional changes at multiple locations of the olfactory system.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.021 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.007 | 0.008 |
| Bibliometrics | 0.008 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".