Ayako Komiyama’s research while affiliated with National Institute of Advanced Industrial Science and Technology and other places

To determine the characteristics of causative factors of taste disorders amongst the elderly, and to examine the therapeutic effect of a zinc agent, taking into account age-related factors. A total of 408 patients with taste disorders were divided into three groups by age: 49 years or younger, 50 to 64 years old, and 65 years or older. The incidence of taste disorders caused by drug administration and systemic disease were significantly higher in the elderly group. A serum zinc concentration of 69 microg/dl or lower was found in 33 per cent of the elderly group, significantly more (p < 0.001) than the 19 per cent of the 49 years or younger group with such a concentration. Zinc administration was therapeutically effective in 70 per cent of the whole population studied, and in 74 per cent of the elderly population. In the elderly, the incidence of taste disorders caused by drug administration or systemic disease was significantly greater compared with other age groups. The curative effects of zinc administration were not observed to be influenced by age.

A 3 M NaCl solution does not stimulate the trigeminal nerve in the human tongue. Objectives. In rats, the trigeminal nerve has been reported to respond when the tongue is stimulated by a solution with an NaCl concentration of 0.4 M or greater. We have attempted to clarify whether or not relatively high concentrations of NaCl stimulate the trigeminal nerves of the human tongue. We examined four patients whose bilateral chorda tympani nerves were resected during middle ear surgeries. We performed subjective tactile and taste tests. Next, we conducted objective examinations of the subjects' tactile and gustatory functions by magnetoencephalography (MEG). The subjective examination confirmed that all four subjects maintained normal tactile sensory functions in their tongues and that the gustatory sensation at their lingual apexes was totally abolished. Furthermore, the objective examination of the tactile function using MEG indicated that their brain responses to trigeminal nerve stimulations were normal. Further examination using MEG failed to produce brain responses to a 3 M NaCl solution in spite of their normally functioning trigeminal nerves. Therefore, we concluded that a 3 M NaCl solution does not stimulate the trigeminal nerve at the tip of the human tongue.

First bite syndrome (FBS) after surgical removal of tumors of the parapharyngeal space has been reported recently. According to the literature, the cause has been estimated to involve interruptions of nerves during the surgery around the superior cervical ganglion and sympathetic nerve plexus of the external carotid artery, which cause supersensitivity of parasympathetic nerves in the parotid gland. Excessive contraction of myoepithelial cells in the parotid gland due to parasympathetic supersensitivity leads to the development of a sharp pain in the parotid region. This report includes exclusive cases of sympathetic neurilemomas of the parapharyngeal space that we had treated, along with a discussion of etiologic factors and the background of FBS.

Tezon® is a supplement containing trace elements (iron, zinc, copper, selenium, and other minerals). We presented this supplement for 10 taste disorder patients (32 to 72 years old, mean 56.3 years old, four males and six females). Serum copper/zinc ratios were improved and selenium levels were raised in all cases. The overall rate of improvement in all patients was 80% (eight cases). These results indicate that Tezon® may be useful for taste disorder patients.