[Anomalous visual suppression of caloric nystagmus]

In patients with central vestibular disorders it is often seen an anomaly of the nystagmus (either spontaneous or provoked) presenting as a defectuous (or non existing at all) reduction of its intensity, when the glance is fixed in a spot. We report 6 cases with this finding. Detailed clinical records, complete vestibular tests and other ancilliary studies as well, allowing to pinpoint the diagnosis, are set forth. The faulty or anomalous visual suppression is not an uniform response, because three several forms through the electronystagmographic tracins could be checked. One in which visual fixation does not affect at any the course of the nystagmic response, a second in which there is a significative reduction of the studied parameter but clearly pathologic, and the third one in which only with visual fixation nystagmus was seen. We consider that this finding indicates the existence of a central disorder, once sedative drugs are ruled out and the practice of the ENG was realized in good conditions of alertness of the patient.