The effect of eye closure upon the pathological vestibular spontaneous nystagmus.

In the course of one year (September 1973 to September 1974) a total of 784 patients were examined with nystagmography. We were dealing with patients who consulted us for reasons of equilibrium disturbances, sensori-neural hearing loss and/or tinnitus. In 200 patients we observed a definite vestibular spontaneous nystagmus (SN) in supine position. Ocular pendular nystagmus was eliminated. On the basis of these 200 electronystagmographic recordings, the effect of eye closure upon the pathological spontaneous nystagmus was analysed. According to the statistical mean value, spontaneous nystagmus with open eyes in darkness was stimulated by eye closure. Further evaluation revealed, however, that 24% of our patients showed spontaneous nystagmus exclusively with open eyes in darkness, 30% only with closed eyes. Nevertheless, the occurrence of spontaneous nystagmus with either open or closed eyes in darkness, or in both conditions, does not permit topodiagnostic conclusions. The possibility of nystagmus inhibition by eye closure must be considered when the case history indicates a vestibular disturbance but a spontaneous nystagmus with closed eyes in absent in the electronystagmography. The clinical observations in one patient are described in detail for example. To exclude errors, one should search for a spontaneous nystagmus following the necessary examination behind Frenzel's glasses-in case of nystagmography-by closed as well as by opened eyes in darkness.