頭位性めまい症例の検討（第４報） 特に末梢性水平性眼振の発現機序について

Abstract

Thirty-three patients with positional vertigo caused by peripheral vestibular lesions were divided into two types of positional nystagmus on the basis of the direction of nystagmus (horizontal or rotatory) and head positions which induced positional vertigo. One type of positional nystagmus was characterized by direction-changing horizontal positional nystagmus, directed towards the lower part of the ear when the right side was down or the left side was down. This type of positional vertigo was provoked by turning over in bed. The other type of positional nystagmus was characterized by direction-changing rotatory positional nystagmus, which was induced mainly by head positioning in the sagittal plane. This type of positional vertigo was provoked by lying down or getting up. Furthermore, horizontal positional nystagmus was induced strongly only by head rotation in the supine position and not induced (or only weakly induced) by head rotation in the sitting position or the hanging position. The electrophysiological experiments of Fernandez and Goldberg showed that the right side down and left side down positions were typical positions in which utricular neurons were very sensitive to gravity. It was specurated that horizontal positional nystagmus might be caused by utricular dysfunction.