Potential Influence of Olfactory, Gustatory, and Pharyngolaryngeal Sensory Dysfunctions on Swallowing Physiology in COVID‐19

Abstract

Persistent smell and taste disorders have been reported as some of the most common symptoms after COVID-19 (coronavirus disease 2019). Sensory, olfactory, and gustatory functions perform an important role in the initiation and modulation of oropharyngeal swallow biomechanics and salivation as well as in mealtime enjoyment and appetite. Yet, the details of this interaction remain relatively unknown in patients who are infected with and recovering from COVID-19. In this commentary, we discuss the possible impacts of SARS-CoV-2 on the central and peripheral nervous system and consider the pathophysiology of olfactory, gustatory, and pharyngolaryngeal sensory deficits and its influence on deglutition, describing hypotheses and offering guidance for future research.

Characterization of dysphagia and laryngeal findings in COVID-19 patients treated in the ICU—An observational clinical study

“…These are overall higher numbers than in previous studies of dysphagia in critically ill patients. As described, it has been hypothesized that the SARS-CoV-2 virus may induce injury in the central and peripheral nervous system [ 7 ], and that this may impact sensory and motor functions related to swallowing [ 8 , 9 ]. Although we cannot draw any conclusions about the impact of the virus on the sensory and motor functions in this particular patient group, it may be a contributing factor to the ICU-related dysphagia that should be further investigated.…”

“…In particular, dysphagia appears frequent among patients admitted to intensive care due to COVID-19 infection [ 6 ]. It has been hypothesized that the SARS-CoV-2 virus may induce injury in the central and peripheral nervous system [ 7 ] and that this may have an impact on sensory and motor functions related to swallowing [ 8 , 9 ]. Furthermore, critical illness as a consequence of prolonged intensive care, intubation, tracheostomy, and respiratory failure may also impose negative effects on deglutition and laryngeal function in this patient group [ 8 , 10 ].…”

COVID-19 is associated with oropharyngeal dysphagia and malnutrition in hospitalized patients during the spring 2020 wave of the pandemic

“…COVIDrelated MN arises due to increased nutritional requirements (hypercatabolism) and the presence of a severe inflammatory status. Furthermore, oropharyngeal dysphagia (OD) and other COVID symptoms such as cough, dyspnea, diarrhea, ageusia, and anosmia contribute to a hyporexic status, and can make food intake unsafe [6,7]. As such, MN worsens the already poor prognosis of COVID-19, especially in multimorbid older patients [6,8].…”

Neurosensory dysphagia in a COVID-19 patient

“…Patients with Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection can experience long-lasting neurological symptoms, including loss of smell (anosmia) and taste (ageusia) [ 8 ]. The olfactory epithelium and the oral mucosae express the Angiotensin-Converting Enzyme 2 (ACE-2) receptor and Transmembrane Protease Serine 2 (TMPRSS2) proteins, which are entry route for the virus [ 12 ]. Interestingly, both the pharynx and larynx surface cells express these proteins [ 12 ] (Fig.…”

“…The olfactory epithelium and the oral mucosae express the Angiotensin-Converting Enzyme 2 (ACE-2) receptor and Transmembrane Protease Serine 2 (TMPRSS2) proteins, which are entry route for the virus [ 12 ]. Interestingly, both the pharynx and larynx surface cells express these proteins [ 12 ] (Fig. 1 ) and have a mutual sensory innervation through the superior laryngeal branch of the vagus nerve [ 1 ].…”