［第22回前庭研究会］回転検査法の診断的意義:自記クプロメトリーについて
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概要
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Self-recording cupulometry (J. HôZAWA and Y. SASAKI, 1963) has different peculiarities from other turning methods, and is done in the following way:<BR>A test person is placed on a revolving chair, with a constant angular acceleration rate till an initial eye-deviation appears. This initial eye-deviation preceeds the onset of the per-rotatory nystagmus, and can be observed through a television camera in front of the eye. Immediately after the eye-deviation appears, the acceleration is switched off and the rotation with the constant angular velocity is kept on until the perrotatory nystagmus disappears. Next, the constant angular deceleration is given in the same manner as the acceleration. This procedure (constant angular acceleration → onset of eye-deviation → constant angular velocity → disappearance of nystagmus → constant angular deceleration → onset of eye-deviation → constant angular velocity) is repeated for three times. The tachograph of the turning chair shows sensitivities of the cupula - vestibular pathway for "acceleration" and "deceleration". So, we named it "<I>self-recording cupulogram</I>". The magnitude of the given acceleration (or deceleration) is ±2, 6 and 10°/sec<SUP>2</SUP>.<BR>The self-recording cupulogram can be classified into three types.<BR>i) Type 1<BR>The effect of "acceleration" and "deceleration" is identical. The final point of the self-recording cupulogram is always on the base line. This type is normal.<BR>ii) Type 2<BR>The effect of "acceleration" and "deceleration" is not identical. The selfrecording cupulogram always shows a divergence from the base line. This type is caused by a "directional preponderance, D. P".<BR>iii) Type 3<BR>The effect of "acceleration" and "deceleration" is nearly identical in the rotation of 6 or 10°/sec<SUP>2</SUP>, but not in 2 °/sec<SUP>2</SUP>. The self-recording cupulogram showing the divergence with a weaker stimulation (2 °/sec<SUP>2</SUP>) reverts to the base line in accordance with the increase of stimulation (6, 10 °/sec<SUP>2</SUP>).<BR>In this examination, 85% of the 156 cases with vertigo were pathological (Type 2 or 3). Type 3 (reversion type) was found exclusively in cases of peripheral lesion, but not of central lesion.<BR>As a result of the basic investigation, it was comfirmed that the <I>rever sion</I> phenomenon was found in cases of a semicircular canal injury and was caused by differences in the vulnerability of the two kinds of hair-cells in the crista ampullaris.<BR>Therefore, the reversion phenomenon detected by the self-recording cupulometry is a very important symptom for differentiating the peripheral vestibular lesion from the central lesion.<BR>In general, the initial eye-deviation in this turning test could be elicited more clearly in darkness and the <I>reversion</I> phenomenon could be detected more exactly by using an infrared T-V camera.
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