[Electronystagmographic changes in patients with posterior cranial fossa tumors]

Findings of electronystagmography in 30 patients with posterior cranial fossa tumor were analysed. Of the 23 cases of CPA tumor, size varied between 0.7-5.0 cm, the ENG showed: (1) The nystagmus occurred in 83% of patients. (2) In ODT, overshoots was showed in 22% of patients. (3) ETT showed type III or IV curves in 55.6% of patients. (4) OKP test decreased in 59% of patients. (5) Caloric test showed canal paresis in 85% of the patients. (6) Abnormal visual suppression test occurred in 60% of patients. (7) Abnormal ABR was found in 89% of patients. We also found that tumor larger than 2.5 cm presented a central type nystagmus (Bruns nystagmus) and involvement of the eye movement system. The electronystagmographic changes of the tumors of cerebellum (3 cases) and brain stem (4 cases) was discussed.