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:
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).