Exploring the Relation between Glottal Closure and Plasma Substance P: A Study Protocol

Exploring the Relation between Glottal Closure and Plasma Substance P: A Study Protocol

KOICHI TSUNODA,^1,2 SHO HASHIMOTO,³ HIROYUKI KURODA,⁴ TOYOTA ISHII⁵ and MIHIRO TAKAZAWA²

¹Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
²Department of Artificial Organs and Medical Creations, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
³Department of Otolaryngology, National Hospital Organization Sendai Medical Center, Sendai, Miyagi, Japan
⁴Department of Otolaryngology, National Hospital Organization Kobe Medical Center, Kobe, Hyogo, Japan
⁵Department of Otolaryngology, National Hospital Organization Sagamihara Hospital, Sagamihara, Kanagawa, Japan

Glottal incompetence, i.e., reduced ability to produce effective glottal closure, is a problem often associated with aging. The study protocol is presented to determine whether blood substance P (SP) serves as an indicator of glottal closure function among the elderly. SP is involved in the neuromuscular mechanisms of cough; reduced concentration of SP may be a marker for increased risk of aspiration pneumonia. The antihypertensive angiotensin-converting enzyme inhibitor, which also inhibits degradation of SP, has been found to be effective in preventing aspiration pneumonia by strengthening the cough reflex. In this study, we will employ National Hospital Organization self-controlled vocal exercise (NHOEx), which has been shown to improve glottal closure by strengthening the laryngeal adduction muscles. We hypothesize that improved glottal closure by NHOEx may lead to the increase in the plasma concentration of SP, which reflects effective cough reflex. Maximum phonation time (MPT), an indicator of glottal closure, will be measured to assess improvement of glottis-closing function. The study will include 180 patients over 65 years old with dysphonia, dysphagia, or MPT of less than 15 seconds. Based on the speculation that the improved MPT may be associated with changes in SP expression, we will measure the plasma SP before and after 6-month treatment of glottal incompetence using NHOEx. The goal is to verify the reliability of SP as an indicator for glottal closure and swallowing function. Measurement of plasma SP may be helpful for earlier detection of subjects with higher risk of aspiration pneumonia among the elderly.

Keywords —— aspiration pneumonia; glottal closure; maximum phonation time; National Hospital Organization self-controlled vocal exercise; substance P

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Tohoku J. Exp. Med., 2019, 249, 237-240

Correspondence: Koichi Tsunoda M.D., Ph.D., Department of Artificial Organs and Medical Creations; Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo 152-8902, Japan.

e-mail: tsunodakoichi@kankakuki.go.jp