Post Viral Olfactory Dysfunction After SARS-CoV-2 Infection: Anticipated Post-pandemic Clinical Challenge

Area of Science:

• Otolaryngology
• Infectious Diseases
• Neurology

Background:

• Persistent olfactory dysfunction (OD) is a prevalent long-COVID symptom, affecting approximately 12% of individuals six months post-infection.
• Understanding the pathophysiology, diagnosis, and treatment of post-COVID OD is crucial for clinicians managing long-COVID patients.

Purpose of the Study:

• To systematically review the literature on the pathophysiology, diagnostic methods, and treatment options for persistent olfactory dysfunction following COVID-19.
• To provide clinicians with updated information on managing this common post-viral disability.

Main Methods:

• A systematic literature search was conducted across multiple databases (MEDLINE, Cochrane Library, LILACS, Google Scholar, ClinicalTrials.gov, medRxiv) following PRISMA guidelines.
• Keywords included COVID-19, olfactory disorders, smell, anosmia, post-viral olfactory disorders (PVOD), post-COVID, and post-haul.
• 33 published articles and 8 ongoing trials were reviewed for definitions, mechanisms, diagnostic tests, and treatments.

Main Results:

• SARS-CoV-2 can induce conductive, neural, and central olfactory dysfunction.
• Both subjective (visual analogue scale) and objective (e.g., Sniffin' Sticks, UPSIT) olfactory evaluations are available for diagnosis and follow-up.
• Olfactory training is identified as the most reliable and recommended treatment option currently available, despite ongoing clinical trials.

Conclusions:

• Post-COVID olfactory dysfunction is a significant and persistent issue requiring clinical attention.
• A combination of subjective and objective tests can effectively diagnose and monitor olfactory dysfunction.
• Olfactory training is the current gold standard for treating post-COVID-19 olfactory dysfunction.