Electronystagmography: Significant Alterations in Tumors of the Cerebellopontine Recess

A significant nystagmographic alteration in the examination of ten patients with tumors of the cerebellopontine recess was impaired ocular pursuit movements when the eyes were moving towards the side of the lesion as detected by eye tracking and optokinetic tests. Unilateral diminution of optokinetic response was found towards the side of the tumor (moving target towards the unaffected side). The presence of saccades during optokinetic response provided additional information, even when the responses appeared symmetrical. Investigation of spontaneous lateral gaze and positional nystagmus contributed in less extent to the diagnosis of the lesions. A caloric test indicated mainly the side of the lesion, but gave little information as to the size of the tumor.