SARS-CoV-2-induced Sensory Perturbations: A Narrative Review of Clinical Phenotypes, Molecular Pathologies, and Possible Interventions

The acute and post-acute sequelae of SARS-CoV-2 infection have been of great clinical interest since the inception of the COVID-19 pandemic. Despite a high prevalence of individuals with persistent symptoms, a wholistic view of the effects of SARS-CoV-2 on special sensory systems is lacking. Considering the significant impact of normal sensory function on quality of life, the goal of this review is to highlight unresolved issues related to SARS-CoV-2-associated insults to the sensory nervous system. In this narrative review, we discuss the epidemiology of SARS-CoV-2-induced sensory perturbations, underlying pathological mechanisms, and possible therapeutic strategies across the olfactory, gustatory, somatosensory, visual, and auditory systems. Examined literature included studies with human biospecimens, human-derived cell lines, and naturally susceptible animal models, which highlighted evidence of persistent functional disruption in all sensory systems. SARS-CoV-2 infection was associated with persistent inflammation in the olfactory epithelium/bulb, somatosensory ganglia, and gustatory systems, long-term transcriptional perturbations in the sensory central nervous system and peripheral nervous system, and detectable degeneration/apoptosis in the gustatory and visual systems. Few studies have proposed evidence-based therapeutic strategies for attenuating specific sensory abnormalities after SARS-CoV-2 infection. While the olfactory system, and to some extent the visual and somatosensory systems, have been more thoroughly investigated from symptomatology, behavioral and molecular perspectives, there is still an unmet need for the development of therapeutics to treat COVID-induced impairment of these systems. Further, additional attention must be placed on COVID-associated impairment of the gustatory, visual, and auditory systems, which lack detailed mechanistic investigations into their pathogenesis.