Systematic MRI in persistent post-Covid-19 olfactory dysfunction should be reassessed

A Comprehensive Review of COVID-19-Related Olfactory Deficiency: Unraveling Associations with Neurocognitive Disorders and Magnetic Resonance Imaging Findings

Olfactory dysfunction (OD) is one of the most common symptoms in COVID-19 patients and can impact patients' lives significantly. The aim of this review was to investigate the multifaceted impact of COVID-19 on the olfactory system and to provide an overview of magnetic resonance (MRI) findings and neurocognitive disorders in patients with COVID-19-related OD. Extensive searches were conducted across PubMed, Scopus, and Google Scholar until 5 December 2023. The included articles were 12 observational studies and 1 case report that assess structural changes in olfactory structures, highlighted through MRI, and 10 studies correlating the loss of smell with neurocognitive disorders or mood disorders in COVID-19 patients. MRI findings consistently indicate volumetric abnormalities, altered signal intensity of olfactory bulbs (OBs), and anomalies in the olfactory cortex among COVID-19 patients with persistent OD. The correlation between OD and neurocognitive deficits reveals associations with cognitive impairment, memory deficits, and persistent depressive symptoms. Treatment approaches, including olfactory training and pharmacological interventions, are discussed, emphasizing the need for sustained therapeutic interventions. This review points out several limitations in the current literature while exploring the intricate effects of COVID-19 on OD and its connection to cognitive deficits and mood disorders. The lack of objective olfactory measurements in some studies and potential validity issues in self-reports emphasize the need for cautious interpretation. Our research highlights the critical need for extensive studies with larger samples, proper controls, and objective measurements to deepen our understanding of COVID-19's long-term effects on neurological and olfactory dysfunctions.

Infectious disease for the rhinologist

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent literature relating to viral, fungal and bacterial infections and their interactions within the sinonasal tract in the past 18 months.

RECENT FINDINGS

Coronavirus disease 2019 (COVID-19)-associated olfactory dysfunction (OD) is variant dependent. Magnetic resonance imaging studies have found greater olfactory cleft opacification and higher olfactory bulb volume in post-COVID-19 OD. Olfactory training remains the mainstay of treatment, while platelet-rich plasma injections and ultramicronized palmitoylethanolamide and luteolin combination oral supplementation have shown early promise.Consensus statements on paranasal sinus fungal balls and acute invasive fungal sinusitis have been released.Studies on the nasal microbiome have reported Staphylococcus and Corynebacterium as the most abundant genera, with higher levels of Staphylococcus and Corynebacterium being found in patients with chronic rhinosinusitis (CRS) and healthy individuals respectively. However, there is conflicting evidence on the significance of biodiversity of the nasal microbiome found in CRS versus healthy patients.

SUMMARY

While the peak of the COVID-19 pandemic is behind us, its sequelae continue to pose treatment challenges. Further studies in OD have implications in managing the condition, beyond those afflicted post-COVID-19 infection. Similarly, more research is needed in studying the nasal microbiome and its implications in the development and treatment of CRS.