Drushti Birwatkar1, Shweta Kalita2, Alan Hirsch3
1Neurology, 2Neurology and Psychiatry, Spartan Health Sciences University, 3Neurology and Psychiatry, Smell and Taste Treatment & Research Institute
Objective:
Correlation of First Taste Phenomenon elimination with COVID-19 infection
Background:
First Taste Phenomenon, whereby perception of flavor occurs at first bite and then dissipates is associated with chemosensory loss (Hirsch, 2018). Elimination of this Phenomenon associated with COVID-19 has not been described.
Design/Methods:
This 62 year old right handed man presented with upper respiratory tract infection induced chemosensory loss that resolved after treatment of 9 g of phosphatidylcholine. His smell declined to 50% of normal. Taste was lost but he retained his first taste phenomenon. He tested positive for COVID-19 presenting with loss of chemosensation which did not resolve despite treatment with nirmatrelvir/ ritonavir. Symptoms of COVID-19 improved after infection resolution, but First Taste Phenomenon never returned.
Results:
Neurological Abnormalities: Gustatory Testing: Taste threshold: Hypogeusia of 10-30% to sucrose. Electrogustometry Testing: left (L) posterior tongue: 34 (abnormal), right (R) posterior tongue: 34 (abnormal), L anterior tongue: 34 (abnormal), R anterior tongue: 30 (abnormal). Right palate: >32 (abnormal), left palate: >32 (abnormal). Taste Quadrant Testing: Front to back: decreased anteriorly to Sodium Chloride, Sucrose, Quinine Hydrochloride.
Conclusions:
The semiology of First Taste Phenomenon includes Classic First Taste Syndrome with full flavor of food followed by rapid, less than 1 minute, decrement in flavor of food (Hirsch, 2018).Retronasal smell inducing flavor perception as nidus to First Taste Syndrome (Djordjevic, 2004) could be eliminated after COVID-19 infection, which reduces retronasal smell, and induce perceived taste loss (Parma, 2020). This First Taste Phenomenon attributes to temporal decrement in saliva as a consequence of persisted mandibulation- reducing taste threshold sensitivity (Weiffenbach, 1995). COVID-19 worsens such hyposalivation (da Mota Santana, 2021). COVID-19 may eliminate first taste and cause CNS dysfunction via ACE type 2 taste receptor cells dysfunction, (Mastrangelo, 2021) and cytokine storm respectively (Hintschich, 2021). Those with preexisting chemosensory dysfunction, association of COVID on remaining chemosensation is warranted.