A Study On Penüular Nystagmus:Pendular Nystagmus: Its Contribution to the Understanding of Nystagmus Mechanisms

Abstract

The author studied the pendular type of nystagmus by using electronystag-mography (ENG). Some of the findings obtained from the study appear to be common to nystagmus in general, i.e. not restricted to the pendular type. A comparison of the pendular and other types of nystagmus is, therefore, highly interesting and beneficial. Observations and discussions were made on (1) the difference of individual nystagmic patterns, (2) the effect of opening or closing the eyelids on nystagmus, and (3) the factors which make pendular nystagmus jerky such as extraocular-muscular, vestibular, central and optokinetic imbalances. Varied grades of nystagmus-sensation-dissociation (NSD) were found to exist in pendular nystagmus cases when vestibular and optokinetic stimuli were applied. The author is of the opinion that NSD in addition to directional difference observed in optokinetic after-nystagmus is an important clue to nystagmus mechanisms.