Course of recovery from taste receptor disturbance

The course of recovery from taste receptor disturbance was studied in 119 patients with moderate-to-severe taste receptor disturbance that was cured or improved with zinc therapy. Taste receptor disturbance was idiopathic in 45 patients, drug-induced in 38 and due to zinc deficiency in 36. Recovery of taste, evaluated by filter paper disk testing and electrogustometry, followed 1 of 3 patterns: (i) in 54 (45.4%) of the 119 cases, taste improved simultaneously in the anterior (innervated by the chorda tympani nerve) and posterior (innervated by the glossopharyngeal nerve) portions of the tongue; (ii) in 53 (44.5%) of the cases, taste improved in the posterior portion first; and (iii) in 12 (10.1%) of the cases, taste improved in the anterior portion first. Zinc therapy was more effective in patients with the "posterior" pattern of recovery, and these patients also recovered the ability to sense sweet and bitter tastes earlier than other tastes. These results indicate that recovery of taste begins on the posterior portion of the tongue, which has an abundance of taste buds. The results of electrogustometry were not helpful in assessing recovery from taste disturbance, but testing for taste using the filter paper disk method on the posterior portion of the tongue was useful for identifying the onset of recovery.