非減衰振子様回転刺激を用いた垂直半規管機能の評価 健康成人と高齢者との比較

Abstract

Pendular rotation test in a head-tilted position was performed with a stimulus mode; amplitude=360 degrees, frequency=0.1 Hz, and maximal speed=114 deg/sec. The subject's head was tilted 60 degrees backward from the upright position, and then rotated 45 degrees either to the left or right. Using this test procedure, it was possible to evaluate the excitability of vertical semicircular canals, using infra-red CCD camera and a personal computer to analyze nystagmus.There were no significant differences in the maximal slow phase eye velocity (SPEV) or in the maximal amplitude of vertical nystagmus from the anterior or posterior semicircular canal in normal adult subjects. However, a significant difference in the maximal SPEV of vertical nystagmus was found between the anterior semicircular canal and posterior semicircular canal in elderly subjects over 70 years old. Excitability of the posterior semicircular canal was lower than that of the anterior semicircular canal in these elderly subjects. Moreover, excitability of the posterior semicircular canal in elderly persons was lower than that in normal non-elderly subjects.