1992 Volume 1992 Issue Supplement53 Pages 41-46
In neuro-otological diagnosis, examination of abnormal eye movements is important, especially to obtain an objective basis of vertigo as well as useful suggestions on the localization of lesions. The abnormal eye movements may be classified into five groups such as spontaneous nystagmus, provocation nystagmus, abnormalities of induced labyrinthine nystagmus, abnormalities of visually induced eye movements and ocular oscillations.
Among them, the most fundamental role in clinical diagnosis is played b y spontaneous nystagmus, and also by provocation nystagmus. There are three types of spontaneous nystagmus: spontaneous nystagmus in the narrower sense, gaze nystagmus and fixation nystagmus. The latter two are of non-vestibular origin. On the other hand, spontaneous nystagmus in the narrower sense is the spontaneous vestibular nystagmus which can be seen or recorded with the eyes closed or open, gazing straight ahead in darkness, or with Frenzel's glasses.
Provocation nystagmus is usually classified into positional nystagmus, positioning nystagmus and head-shaking nystagmus. The former two are nystagmus of the vestibular type, provoked by certain head positions other than vertical, and have a different meaning from spontaneous nystagmus in the narrower sense in neuro-otological diagnosis. On the contrary, head-shaking nystagmus is a latent spontaneous vestibular nystagmus, which is provocated in a seated patient by rapid head shaking around the vertical axis.
