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Review

Dysautonomia and Implications for Anosmia in Long COVID-19 Disease

Department of Clinical Research and Innovation, Foch Hospital, 92150 Suresnes, France
Academic Editor: Indre Bileviciute-Ljungar
J. Clin. Med. 2021, 10(23), 5514; https://doi.org/10.3390/jcm10235514 (registering DOI)
Received: 13 November 2021 / Revised: 22 November 2021 / Accepted: 24 November 2021 / Published: 25 November 2021
(This article belongs to the Special Issue Long-Term COVID-19: The Lasting Health Impacts of COVID-19)
Long COVID-19 patients often reported anosmia as one of the predominant persisting symptoms. Recent findings have shown that anosmia is associated with neurological dysregulations. However, the involvement of the autonomic nervous system (ANS), which can aggregate all the long COVID-19 neurological symptoms, including anosmia, has not received much attention in the literature. Dysautonomia is characterized by the failure of the activities of components in the ANS. Long COVID-19 anosmia fatigue could result from damage to olfactory sensory neurons, leading to an augmentation in the resistance to cerebrospinal fluid outflow by the cribriform plate, and further causing congestion of the glymphatic system with subsequent toxic build-up in the brain. Studies have shown that anosmia was an important neurologic symptom described in long COVID-19 in association with potential COVID-19 neurotropism. SARS-CoV-2 can either travel via peripheral blood vessels causing endothelial dysfunction, triggering coagulation cascade and multiple organ dysfunction, or reach the systemic circulation and take a different route to the blood–brain barrier, damaging the blood–brain barrier and leading to neuroinflammation and neuronal excitotoxicity. SARS-CoV-2 entry via the olfactory epithelium and the increase in the expression of TMPRSS2 with ACE2 facilitates SARS-CoV-2 neurotropism and then dysautonomia in long COVID-19 patients. Due to this effect, patients with anosmia persisting 3 months after COVID-19 diagnosis showed extensive destruction of the olfactory epithelium. Persistent anosmia observed among long COVID-19 patients may be involved by a cascade of effects generated by dysautonomia leading to ACE2 antibodies enhancing a persistent immune activation. View Full-Text
Keywords: COVID-19; dysautonomia; long COVID-19; anosmia; ACE2; neurotropism COVID-19; dysautonomia; long COVID-19; anosmia; ACE2; neurotropism
MDPI and ACS Style

Vallée, A. Dysautonomia and Implications for Anosmia in Long COVID-19 Disease. J. Clin. Med. 2021, 10, 5514. https://doi.org/10.3390/jcm10235514

AMA Style

Vallée A. Dysautonomia and Implications for Anosmia in Long COVID-19 Disease. Journal of Clinical Medicine. 2021; 10(23):5514. https://doi.org/10.3390/jcm10235514

Chicago/Turabian Style

Vallée, Alexandre. 2021. "Dysautonomia and Implications for Anosmia in Long COVID-19 Disease" Journal of Clinical Medicine 10, no. 23: 5514. https://doi.org/10.3390/jcm10235514

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