Comparative imaging study of patients with persistent olfactory dysfunction due to mild COVID-19 using structural and functional MRI.

INTRODUCTION: Persistent post-COVID olfactory dysfunction continues to be studied due to the controversy in its pathophysiology and neuroimaging. MATERIALS AND METHODS: The patients had confirmed mild COVID-19 infection with olfactory dysfunction of more than one month of evolution and they were compared to controls with normal olfaction, assessed using the Sniffin' Sticks Olfactory Test and underwent brain, magnetic resonance imaging (MRI) of the olfactory bulb and olfactory function. RESULTS: A total of 8 patients and 2 controls participated. The average age of the patients was 34.5 years (SD 8.5), and that of the controls was 28.5 (SD 2.1). The average score in the patients' olfactory test was 7.9 points (SD 2.2). In brain and olfactory bulb MRI tests, no morphological differences were found. When evaluated by functional MRI, none of the patients activated the entorhinal area in comparison to the controls, who did show activation at this level. Activation of secondary olfactory areas in cases and controls were as follows: orbitofrontal (25% vs 100%), basal ganglia (25% vs 50%) and insula (38% vs 0%) respectively. CONCLUSIONS: There were no observed morphological changes in the brain MRI. Unlike the controls, none of the patients activated the entorhinal cortex in the olfactory functional MRI.

Persistent olfactory dysfunction in mild COVID-19 patients: A descriptive study of the characteristics and association with other symptoms.

Introduction: Post-COVID olfactory dysfunction continues to be studied due to the controversy of the mechanisms involved. The aim was to investigate the olfactory dysfunctions in association with other post-COVID symptoms. Material and methods: Observational, descriptive and single-center study. The patients had confirmed mild COVID-19 and subjective olfactory dysfunction of more than a month of evolution, which was assessed by Sniffin' Sticks Olfactory Test. Results: A total of 86 patients participated. The mean age was 37.2 years (SD 9.82). 70.9% reported parosmia and 46.5% symptoms of brain fog. A pathological test result was obtained in 72.1% of the participants. The most failed pen was 11 (apple) in 76.7%. Anosmia of pen 15 (anise) was reported more frequently in 24.4% and cacosmia of pen 9 (garlic) in 27.9%. We observed a significant association between patients who reported parosmias and brain fog (RR 2.18; p = 0.018), also between parosmia and phantosmia (RR 6.042; p < 0.001). Conclusion: There is some pathological selectivity for certain test pens, a higher prevalence of cognitive symptoms and many patients with combined parosmia and brain fog.

Introducción: La alteración olfatoria post-COVID continúa en estudio por la controversia sobre los mecanismos implicados. El objetivo de este estudio es caracterizar las alteraciones olfatorias y su relación con otros síntomas post-COVID. Material y métodos: Estudio unicéntrico, observacional y descriptivo. Los pacientes tuvieron infección por COVID-19 leve confirmada y disfunción olfatoria subjetiva de más de un mes de evolución, evaluada con el Sniffin' Sticks Olfatory Test. Resultados: Se seleccionaron 86 pacientes. La edad media fue de 37,2 años (DE 9,82). El 70,9% refirieron parosmia y el 46,5% niebla mental. Se obtuvo un test patológico en el 72,1% de los participantes. El lápiz más fallado fue el número 11 (manzana), en el 76,7%. La anosmia fue reportada más frecuentemente con el lápiz 15 (anís) y la cacosmia con el lápiz 9 (ajo) en el 27,9%. Observamos una asociación significativa entre pacientes que refieren parosmias y niebla mental (RR 2,18; p = 0,018) y entre parosmia y fantosmia (RR 6,042; p < 0,001). Conclusión: Se observa anosmia y cacosmia selectiva para algunos olores testados. Hay una alta prevalencia de síntomas cognitivos, más frecuentes en pacientes con parosmia.

Persistent olfactory dysfunction in mild COVID-19 patients: A descriptive study of the characteristics and association with other symptoms / Alteración olfatoria persistente en pacientes con infección leve por COVID-19: estudio descriptivo de las características y su asociación con otros síntomas

Introduction: Post-COVID olfactory dysfunction continues to be studied due to the controversy of the mechanisms involved. The aim was to investigate the olfactory dysfunctions in association with other post-COVID symptoms.Material and methodsObservational, descriptive and single-center study. The patients had confirmed mild COVID-19 and subjective olfactory dysfunction of more than a month of evolution, which was assessed by Sniffin’ Sticks Olfactory Test.ResultsA total of 86 patients participated. The mean age was 37.2 years (SD 9.82). 70.9% reported parosmia and 46.5% symptoms of brain fog. A pathological test result was obtained in 72.1% of the participants. The most failed pen was 11 (apple) in 76.7%. Anosmia of pen 15 (anise) was reported more frequently in 24.4% and cacosmia of pen 9 (garlic) in 27.9%. We observed a significant association between patients who reported parosmias and brain fog (RR 2.18; p=0.018), also between parosmia and phantosmia (RR 6.042; p<0.001).ConclusionThere is some pathological selectivity for certain test pens, a higher prevalence of cognitive symptoms and many patients with combined parosmia and brain fog. (AU)

Introducción: La alteración olfatoria post-COVID continúa en estudio por la controversia sobre los mecanismos implicados. El objetivo de este estudio es caracterizar las alteraciones olfatorias y su relación con otros síntomas post-COVID.Material y métodosEstudio unicéntrico, observacional y descriptivo. Los pacientes tuvieron infección por COVID-19 leve confirmada y disfunción olfatoria subjetiva de más de un mes de evolución, evaluada con el Sniffin’ Sticks Olfatory Test.ResultadosSe seleccionaron 86 pacientes. La edad media fue de 37,2 años (DE 9,82). El 70,9% refirieron parosmia y el 46,5% niebla mental. Se obtuvo un test patológico en el 72,1% de los participantes. El lápiz más fallado fue el número 11 (manzana), en el 76,7%. La anosmia fue reportada más frecuentemente con el lápiz 15 (anís) y la cacosmia con el lápiz 9 (ajo) en el 27,9%. Observamos una asociación significativa entre pacientes que refieren parosmias y niebla mental (RR 2,18; p=0,018) y entre parosmia y fantosmia (RR 6,042; p<0,001).ConclusiónSe observa anosmia y cacosmia selectiva para algunos olores testados. Hay una alta prevalencia de síntomas cognitivos, más frecuentes en pacientes con parosmia. (AU)

Persistent olfactory dysfunction in mild COVID-19 patients: A descriptive study of the characteristics and association with other symptoms.

INTRODUCTION: Post-COVID olfactory dysfunction continues to be studied due to the controversy of the mechanisms involved. The aim was to investigate the olfactory dysfunctions in association with other post-COVID symptoms. MATERIAL AND METHODS: Observational, descriptive and single-center study. The patients had confirmed mild COVID-19 and subjective olfactory dysfunction of more than a month of evolution, which was assessed by Sniffin' Sticks Olfactory Test. RESULTS: A total of 86 patients participated. The mean age was 37.2 years (SD 9.82). 70.9% reported parosmia and 46.5% symptoms of brain fog. A pathological test result was obtained in 72.1% of the participants. The most failed pen was 11 (apple) in 76.7%. Anosmia of pen 15 (anise) was reported more frequently in 24.4% and cacosmia of pen 9 (garlic) in 27.9%. We observed a significant association between patients who reported parosmias and brain fog (RR 2.18; p=0.018), also between parosmia and phantosmia (RR 6.042; p<0.001). CONCLUSION: There is some pathological selectivity for certain test pens, a higher prevalence of cognitive symptoms and many patients with combined parosmia and brain fog.

Effect of Reverse End-to-Side (Supercharging) Neurotization in Long Processed Acellular Nerve Allograft in a Rat Model.

PURPOSE: Processed acellular nerve allograft (PNA) has been suggested as a convenient tool for overcoming short and medium nerve defects. Although the clinical implications are unclear, animal data suggest that PNA becomes less effective at longer lengths. Although reverse or supercharging end-to-side nerve transfer may improve the neurotrophic potential in chronically denervated nerve tissue, the application of this strategy to long acellular nerve allograft has not been previously investigated. We hypothesized that supercharging acellular nerve allograft would increase its effective length. METHODS: Sprague-Dawley and Thy1-green fluorescent protein Sprague-Dawley rats underwent transection of the tibial nerve, followed by immediate repair with 20-, 40-, or 60-mm acellular nerve allografts processed identically to commercially available human acellular nerve allograft (AxoGen, Inc., Alachua, FL) or isograft. Half of the allograft group was supercharged with a reverse end-to-side transfer from the ipsilateral peroneal nerve. At 10 weeks, the reconstructed nerve in the Thy1-green fluorescent rat groups were exposed and examined under a fluorescence-enabled microscope. At 20 weeks, the remaining rats underwent motor testing and tissue harvest for morphological examination. RESULTS: In comparison with a nonenhanced allograft, supercharging had a statistically significant positive impact on the reinnervated muscle normalized force generation and distal axon counts for all graft sizes. Muscles in the supercharged group were heavier than those in the allograft group for the 40-mm-length grafts and G-ratio measurements were higher in the supercharged allograft group for 60-mm-length grafts only. CONCLUSIONS: This study supports that hypothesis that supercharging nerve transfer improves axon regeneration within PNA. CLINICAL RELEVANCE: When an appropriate donor nerve is available, supercharging nerve transfer may improve nerve regeneration in PNA across long nerve defects.