Optokinetic Nystagmus In Acoustic Neuromas

Abstract

In 17 patients with operatively confirmed, mostly large acoustic neuromas, optokinetic nystagmus was analysed relative to the size of the tumour and its relation to the brain stem. In 6 patients optokinetic nystagmus was abnormal, and in these cases the tumour was large or very large, in most cases adherent to the brain stem. Abnormal optokinetic nystagmus is due to pressure by the tumour upon the pontine optokinetic centre. In 11 patients optokinetic nystagmus was normal; in 5 of these patients the tumour was small or medium-sized, in 6 large, but in only one case adherent to the brain stem. The test for optokinetic nystagmus is a simple procedure which is of importance in assessing the extent of the tumour and its relation to the brain stem, and it ought to be used as a routine in the otoneurological diagnosis of acoustic neuromas.