Studies of the inner ear
One of the main researches is to reveal function of the inner ear morphologically and physiologically, especially the homeostasis of water in the inner ear. The inner ear includes the perilymphatic and endolymphatic compartments. In Meniere disease, the iron balance between the two compartments is deteriorated. Hence, the important point is what maintains the balance.
Our studies demonstrated over production of the antidiuretic hormone in patients with Meniere disease. The hormone connects to a receptor in the kidney, and mediates expression of water channels by which water enables to go through membrane selectively. We determined that the inner ear has the same system to sustain the balance as kidney, and the antidiuretic hormone deteriorated the balance of the perilymphatic and endolymphatic systems. Moreover, the hormone induced a vertigo were also reported. We aim to find novel treatments by such studies associating with the disease.
Studies of laryngeal function
The larynx involves various functions such as speech, respiration and deglutition, etc. These functions are controlled by the intrinsic laryngeal muscles which are regulated by the coordination and contradiction of the muscle each. We investigated neuro-regulation system for the muscles morphologically, demonstrating the muscle spindle, which is a receptor of elasticity, exists in almost of the muscles, and suggesting that the muscle spindle works for feedback regulation of muscle strains. The other studies about subneural apparatuses of sensorial nerve revealed the morphology varied and worked for a receptor of sensory. These studies indicate that the muscle spindles and subneural apparatuses associate with coordination of complex laryngeal function.
Studies of age-related alteration of swallowing
Swallowing is accomplished by precise and coordinated movements of various muscles. The swallowing function progressively deteriorates with advancing age, therefore aspiration pneumonia is one of main causes of death.
Age-related alteration of the swallowing function was assessed with videoendoscopy, videofluoroscopy and manometory in our study. The study demonstrated late response of swallowing reflex, extension of the pharyngeal transit time and dysfunction of upper esophageal sphincter (UES), etc. in the pharyngeal swallowing phase of over 70-year-old people. In terms of dysfunction of UES, disturbance of esophageal opening, and enlargement of UES region were revealed, causing the disturbance of food passage. Furthermore, these worsen parameters of swallowing functions were improved by being given constituent of hot taste in a cayenne, the capsaicin. These results imply that the capsaicin is effective for treatment and prevention of swallowing disorder in the elderly.