Divergent nystagmus: recordings from an advanced system of infra-red oculography

Because of some limitations in photoelectric nystagmography, a new system of binocular infra-red oculography (BIRO) was developed. The advantages of BIRO are excellent linearity up to +/- 20 degrees horizontal eye movement, sensitivity of at least 0.1 degree of eye movement and the possibility of obtaining binocular recordings. In the course of a routine clinical evaluation, divergent nystagmus was recorded in 2 patients. This occurred both spontaneously and following caloric stimulation. A vascular brain stem pathology was strongly suspected from magnetic resonance imaging (MRI) studies. The possible mechanisms of divergent nystagmus are discussed.