Galvanic Body Sway Test—刺激方法についての検討

Clinical Application of Galvanic Body Sway Test-Comparative Study on Various Stimulating Methods

　はじめに

　Galvanic body sway test（以下GBSTと略す）は，前庭系の検査のなかで，内耳障害と後迷路障害を鑑別し得る有力な検査と考えられている。しかし，この検査法は，被験者固有の不規則な重心動揺波形の上に電気性身体動揺を重ねる検査であるために，全例において鮮明な波形が得られるとは限らず，またすべての波形成分が安定して得られるわけではない。これまでに各波形頂点が，2峰性となったり，平坦化し計測が困難となる例もあり反応の判定に苦慮する場合があった。今回，著者はGBSTの再現性を向上させるために刺激回数，刺激時間，刺激電流を変えて比較検討し，興味ある知見を得たのでここに報告する。

Galvanic body sway test (GBST) is considered to be useful to expedite differential diagnosis between vestibular and retrovestibular lesions. However, difficulty in evaluation of the response may some-times occur when the basic body sway of an exami-nee during standing upright is relatively large.

The purpose of this study is to detect the most adequate test method, and GBST was examined by changing stimulating conditions, such as the dura-tion time, electric current and frequency of the monopolar stimulation, in 13 normal subjects.

GBST became mostly clear by computer averag-ing the response induced by 20 successive trials of galvanic stimulations, at 0.5 mA, for the duration of 5 sec in each stimulus and interval time 4 sec. The method with those stimulating conditions should be available for the clinical use.