Ageusia

Definition

Ageusia is the loss of the sense of taste. The disorder should be distinguished from a disruption in the ability to perceive flavor, which requires a combination of olfactory, gustatory, and somatosensory functions. Frequently, complaints of ageusia are often explained by olfactory dysfunction rather than a disruption in taste perception, per se. The majority of taste receptors (buds) are located on the tongue and this information is carried by the VIIth (anterior two thirds) and IXth (posterior third) cranial nerves, with other taste receptors (cranial nerve X) located in other regions of the mouth and throat. These taste fibers enter the solitary nucleus (rostral portion) in the upper medulla and from there second-order neurons travel to the ventral posterior medial nuclei of the thalamus. Thalamic projections carrying this gustatory information then project to the postcentral gyrus in the region of the parietal operculum and to the underlying insular cortex where the...