Neurolocalization of taste disorders

Bedside Examination Technique for Taste

Taste disorders are uncommon and frequently unrecognised during neurological and even oral examinations. Nevertheless, understanding taste pathway, its disorders, as well as assessment of taste are crucial as it can reveal various oral, systemic and neurological pathologies that manifest as an alteration of taste. Multiple taste examination techniques have been described in the literature; however, certain techniques are complicated and may not be feasible. This paper describes the adoption of a relatively simple technique for taste assessment that can be performed at the bedside. The bedside detection of taste disorders will allow examiners to assign the patient for more detailed and invasive taste assessments.

Dysgeusia: A review in the context of COVID-19

Background

Taste disorders in general, and dysgeusia in particular, are relatively common disorders that may be a sign of a more complex acute or chronic medical condition. During the COVID-19 pandemic, taste disorders have found their way into the realm of general as well as specialty dentistry, with significance in screening for patients who potentially may have the virus.

Types of Studies Reviewed

The authors searched electronic databases (PubMed, Embase, Web of Science, Google Scholar) for studies focused on dysgeusia, ageusia, and other taste disorders and their relationship to local and systemic causes.

Results

The authors found pertinent literature explaining the normal physiology of taste sensation, proposals for suggested new tastes, presence of gustatory receptors in remote tissues of the body, and etiology and pathophysiology of taste disorders, in addition to the valuable knowledge gained about gustatory disorders in the context of COVID-19. Along with olfactory disorders, taste disorders are one of the earliest suggestive symptoms of COVID-19 infection.

Conclusions

Gustatory disorders are the result of local or systemic etiology or both. Newer taste sensations, such as calcium and fat tastes, have been discovered, as well as taste receptors that are remote from the oropharyngeal area. Literature published during the COVID-19 pandemic to date reinforces the significance of early detection of potential patients with COVID-19 by means of screening for recent-onset taste disorders.

Practical Implications

Timely screening and identification of potential gustatory disorders are paramount for the dental care practitioner to aid in the early diagnosis of COVID-19 and other serious systemic disorders.

Care need and dry mouth as risk indicators for impaired taste and smell

To identify whether reduced saliva secretion or xerostomia symptoms are risk indicators for impaired taste and smell, depending on age and care needs. This cross-sectional study evaluated taste and smell in patients categorized into different age groups (<65> years) and different care need, with and without dry mouth. Of the 185 patients included, 119 were classified as “dry mouth” and 66 as “without dry mouth”. Overall, 103 (55.7%) were female and 37 (20%) needed care. There was no difference between “dry mouth” and “without dry mouth” regarding identification of odors or tastes, but a difference in the number of correctly identified odors and tastes in favor of “without care need” patients (p < 0.05). The ability to identify smells and tastes was negatively influenced by age, number of medications, and number of comorbidities, but subjective dry mouth had no impact. According to our results, subjective dry mouth is not a risk factor for an impaired ability to recognize smells and tastes. However, care need representing age, the number of medications taken, and the number of chronic comorbidities is a risk indicator.

SARS-CoV-2 invasion of the central nervous: a brief review

There is increasing evidence of the ability of the novel coronavirus to invade the central nervous system (CNS). But how does a respiratory virus invade the highly protected CNS? Here, we reviewed available literature and case reports to determine CNS involvement in COVID-19, and to identify potential regions of the brain that may be affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its possible route of entry into the brain to identify its pathogenicity. Based on the symptoms, the parietal lobe and the cerebellum are the likely targets of SARS-CoV-2; however, further work is needed to elucidate this. The presence of ACE2, used by SARS-CoV-2 for cell entry, in the brain as well as detection of the virus in the cerebrospinal fluid, further assert that SARS-COV-2 targets the brain, and therefore, medical practitioners should take that into account when dealing with patients suffering from COVID-19.

Are we facing a crashing wave of neuropsychiatric sequelae of COVID-19? Neuropsychiatric symptoms and potential immunologic mechanisms

The coronavirus disease 19 (COVID-19) pandemic is a significant psychological stressor in addition to its tremendous impact on every facet of individuals' lives and organizations in virtually all social and economic sectors worldwide. Fear of illness and uncertainty about the future precipitate anxiety- and stress-related disorders, and several groups have rightfully called for the creation and dissemination of robust mental health screening and treatment programs for the general public and front-line healthcare workers. However, in addition to pandemic-associated psychological distress, the direct effects of the virus itself (several acute respiratory syndrome coronavirus; SARS-CoV-2), and the subsequent host immunologic response, on the human central nervous system (CNS) and related outcomes are unknown. We discuss currently available evidence of COVID-19 related neuropsychiatric sequelae while drawing parallels to past viral pandemic-related outcomes. Past pandemics have demonstrated that diverse types of neuropsychiatric symptoms, such as encephalopathy, mood changes, psychosis, neuromuscular dysfunction, or demyelinating processes, may accompany acute viral infection, or may follow infection by weeks, months, or longer in recovered patients. The potential mechanisms are also discussed, including viral and immunological underpinnings. Therefore, prospective neuropsychiatric monitoring of individuals exposed to SARS-CoV-2 at various points in the life course, as well as their neuroimmune status, are needed to fully understand the long-term impact of COVID-19, and to establish a framework for integrating psychoneuroimmunology into epidemiologic studies of pandemics.