Taste damage (otitis media, tonsillectomy and head and neck cancer), oral sensations and BMI

Otitis media and tonsillectomy are associated with enhanced palatability of energy dense foods and with weight gain. Otitis media can damage the chorda tympani nerve (CN VII); tonsillectomy and head and neck radiation treatment can damage the glossopharyngeal nerve (CN IX). Both of these nerves function prominently in taste sensation. The present study utilizes these sources of damage to study central interactions among the nerves that mediate oral sensations. Mild damage restricted to one of these nerves can actually intensify sensations evoked from undamaged nerves (i.e., whole-mouth taste, oral tactile sensations evoked by fats and irritants). These intensifications may result from disruption of central inhibitory taste circuits, as taste damage appears to disinhibit other oral sensory nerves. In addition, mild damage restricted to one taste nerve can intensify odors perceived from foods in the mouth during chewing and swallowing (i.e., retronasal olfaction); this may be a secondary consequence of the intensification of whole-mouth taste. Damage to both nerves leads to widespread oral sensory loss. At present, the link between sensory alterations and weight gain has not been established for adults (e.g., does increased fat preference occur in individuals with oral sensory intensifications, those with losses, or both?). Finally, pain in non-oral locations is also related to taste loss. When participants rated "the most intense pain of any kind they had ever experienced," those with the greatest taste loss gave the highest ratings. These effects suggest that taste loss significantly influences long-term health outcomes.