抄録
Two patients exhibiting spontaneous pure rotatory nystagmus at frontal gaze without other specific signs are presented. Such an ocular sign is usually peculiar to the bulbar lesion especially to the vestibular nuclei lesion.
Case 1 : A 48 year-old female consulted our clinic complaining only of shoulder stiffness. However, objectively a peculiar ocular sign of spontaneous pure rotatory nystagmus was observed, from which a bulbar lesion was suspected. Vertebral angiography disclosed a tumor in the medulla extending to the left cerebello-pontine angle. On operation, the tumor was disclosed to be meningioma.
Case 2 : When a 36 year-old male consulted a neurosurgical department because of minor head injury, the peculiar ocular sign was detected. This patient was suspected of having a bulbar lesion as well, so that tomography of PEG was done. A soft mass was disclosed at the anterior part of the medulla.
Two cases of benign extramedullary tumor at the medulla are reported. The tentative diagnosis was obtained on the basis of the specific ocular sign which was then confirmed morphologically. The mechanism of the spontaneous pure rotatory nystagmus is also discussed.
