Failure of suppression of post-caloric nystagmus by fixation.

One hundred and seven patients who had failure of fixation suppression (FFS) of their post-caloric nystagmus were studied. Most of them had other ocular motor abnormalities such as defective pursuit, gaze paretic and rebound nystagmus, and saccadic dysmetria. The presence of FFS was unrelated to the type of post-caloric response. The data from this study are compatible with the idea that FFS is a manifestation of a disturbance in the visual-vestibular interaction. While FFS alone is not a useful localizing sign, its presence is patients who are not taking drugs should lead to a search for neurological disease particularly in the posterior fossa.