Taste, smell, and trigeminal chemesthesis in COVID-19 patients

Abstract

University of WashingtonAbstract Taste, smell, and trigeminal chemesthesis in COVID-19 patients Suhaib Borgeia Chair of the supervisory committee:Professor & Director: Susan Coldwell Oral Health Sciences COVID-19 is an infectious disease that spreads quickly, requires hospitalization for some patients, and has prolonged effects on the lungs and other body organs. Two early prevalent symptoms of the disease are olfactory and gustatory dysfunction. While most patients regain chemosensory function following recovery from COVID-19, some patients have lingering chemosensory abnormalities. This thesis is focused on identifying a methodology suitable for assessing chemosensory function in the dental clinic. Identifying suitable tests will allow dentists and oral medicine specialist to detect COVID-19-related sensory abnormalities as well as monitor recovery of sensory function over time. Objective: to assess the ability of selected objective measures of olfactory, gustatory, and chemesthesis (oral trigeminal nerve) function to detect alterations in sensory function in a cohort of patients who have recovered from COVID-19. Methods: subjects recruited through a flyer and social media advertising took an online survey based on one developed by the Global Consortium for Chemosensory Research (GCCR, https://gcchemosensr.org). The survey asked questions about COVID-19 diagnosis and symptoms, including changes in smell, taste, and chemesthesis function. Subjects completed objective testing of chemosensory function at the University of Washington Oral Medicine Clinic. Olfactory sensitivity was assessed using the Smell Identification Test (SIT). Gustatory sensitivity was evaluated using a modification of the NIH Toolbox protocol for assessing gustatory function in adults. Chemesthesis was assessed using a capsaicin-containing pullulan-based dissolving strip. All subjects were also tested using semi-quantitative sensory testing to assess trigeminal function in various receptive fields (V1, V2, V3). Psychological assessments included the Patient Health Questionnaire (PHQ-9) and General Anxiety Disorders (GAD-7) scales. Subjects completed a medical review form. An intra-oral examination and dry mouth assessment were also performed. Results: Eleven subjects responded to advertisements and completed the online survey. Nine completed the study protocols. Four of those completing the study had a prior COVID-19 infection, while five did not report prior COVID-19 infection. For those four subjects with prior COVID-19 infection, two self-reported changes in olfaction with COVID-19 infection, two self-reported changes in sensitivity to tastes with COVID-19 infection, and one self-reported change in chemesthesis with COVID-19 infection. One of the two COVID-19 patients reported that olfactory sensitivity had subsequently recovered, while the other reported lingering reductions in olfactory sensitivity. Both patients with taste issues during COVID-19 self-reported that taste function had recovered to “excellent sense”. The patient with COVID-19-related deficits in chemesthesis self-reported lingering loss of sensitivity to spicy foods. Objective testing with SIT failed to discriminate the case with lingering olfactory dysfunction from controls. No evidence of taste dysfunction was observed in any of the cases compared with controls. Objective testing with the capsaicin strip confirmed a lack of sensitivity to capsaicin in the case reporting a lingering loss of chemesthesis. Semi-quantitative testing of the trigeminal receptive fields did not reveal any abnormalities among cases. An abnormal finding was observed in one control. Conclusion: Although the SIT is considered a gold-standard clinical measure of olfactory dysfunction, it did not detect smell loss in a single patient with lingering olfactory complaints. No patients reported lingering taste concerns, so the usefulness of the NIH Toolbox protocol for monitoring COVID-19-related taste loss could not be assessed. The finding that a patient with self-reported lingering chemesthesis loss also had a muted response to the capsaicin-containing pullulan-based dissolving strip indicates that this test may be helpful in detecting, quantifying, and monitoring chemesthesis issues in long COVID.