Gustatory function assessment
A standardized and validated test, which investigates the ability to
perceive four primary tastes (sweet, salty, sour and bitter) was used to
evaluate the gustatory function [12,13]. Four solutions, one for
each primary taste, were prepared as follows:
- Salted solution: 30 g of table salt were added to 1 liter of deionized
water.
- Sweet solution: 30 g of refined sugar were dissolved in 1 liter of
deionized water.
- Sour solution: 90 mL of commercial 100% lemon juice added to 1 liter
of deionized water.
- Bitter solution: unsweetened decaffeinated coffee.
Deionized water was used as control. During the trial, 1 ml of each
solution was dropped onto the center of the patient tongue. A different
cotton swab was used for each of the solutions and then disposed. The
patient was then asked to indicate whether the perceived flavor was
sweet, salty, bitter, acid or neutral. The solutions were presented in a
random order, excluding the bitter taste, which was always presented
last because it tends to alter subsequent taste perception [12].
The answers were recorded as either correct or incorrect. Taste score
ranged from 0 to 4 allowing to classify the patients into four
categories: Normal (score 4), mild hypogeusia (score 3), moderate
hypogeusia (score 2), severe hypogeusia (score 1) and ageusia (score 0).