垂直半規管刺激性回転後眼振 健常耳での外側半規管刺激との比較

Abstract

To test vertical semicircular canal function, we developed a new and convenient type of rotation-chair, in which subjects sat with their heads and backs tilting backward 60°and with their heads rolling laterally 45°. A CCD camera and infrared video system was used to record eye movement in the dark. Normal subjects were rotated with an acceleration of 2°/sec2 until the angular velocity reached 60°/sec. The rotation was then stopped with a deceleration of 100°/sec2 after per-rotation nystagmus subsided. The maximal slow phase eye velocity (MSPEV) of vertical components of vertical semicircular canal (VSCC)-induced post-rotatory nystagmus (PRN) were analysed.Subjects were first rotated with laterally rolling head angles of 30°, 45° and 60°to examine the optimal angle for stimulating VSCC.MSPEV of posterior semicircular canal (PSCC)-induced PRN was largest with a head angle of 60°. While MSPEV of anterior semicircular canal (ASCC)-induced PRN did not vary with the laterally rolling head angle. MSPEV of the vertical components of VSCC-induced PRN was then compared with that of the horizontal components of lateral semicircular canal (LSCC)-induced PRN. MSPEV of both PSCC- and ASCC-induced PRN were significantly smaller than that of LSCC-induced PRN.MSPEV of ASCC-induced PRN was slightly smaller than that of PSCC-induced PRN, though individual differences varied widely. However, there were very small leftright differences in MSPEV of both PSCC- and ASCC-induced PRN. Therefore, it is suggested that our PRN function test involving VSCC can diagnose vestibular diseases.