Yuichiro Saito

NEURO-OTOLOGICAL STUDY OF POSITIONAL VERTIGO CAUSED BY HEAD INJURY

A neuro-otological examination was given to 22 patients with paroxysmal positional vertigo within 1 week of head injury. In all cases, reverse rotatory positional nystagmus accompanied by a vertiginous sensation was observed in the positional nystagmus test. No relationship between the affected side and the direction of eye movement in the head-hanging position was found in the positional nystagmus test. From the prognosis and the nystagmus findings, the cause of the vertigo was thought to be partial damage to the inner ear. The clinical course was generally favorable, but recovery was slower in the 11 cases with neuro-otologically demonstrated central nervous system disorders than in the other 11 cases.

Scanning electron microscopic studies of the membranous labyrinth after transtympanic infusion of local anesthetics (lidocain).

Scanning electron microscopic observation of the transtympanic infusion of 10% xylocain revealed twisting and disorders of outer hairs especially from the 2nd and 3rd rows of the basal to the 2nd turn of the organ of Corti, and adhesion and fusion of the sensory hairs of the crista ampullaris and otolith organ 1 and 4 days after injection. Four percent xylocain however demonstrated very minor alteration of the sensory hairs and no missing sensory hairs were detected from any cases. The authors hypothesized from electron microscopic observation that adhesion and fusion of vestibular sensory hairs or twisting and disorders of the sensory hairs of the organ of Corti might act to intercept harmful circulation of exclusion of abnormal excitement of hair cells and the innovation of electrical discharge of sensory hairs due not only to the pharmacological effects of xylocain but also to osmotic pressure.

A case of metastatic cerebellar breast cancer that had positional vertigo as its chief complaint

With vertigo patients, it is important that we pay attention to vertigo caused by central lesions as there are different diagnoses. Vertigo caused by central lesions such as brain tumors and cerebellar infarction sometimes appear as if the lesions were peripheral ones. The patient in the present study was a 50 y.o. female, with cerebellar metastasis caused by breast cancer and whose chief complaint was positional vertigo at a glance. However, detailed interview, past history, and careful neuro-otological findings based on nystagmus and the results of electric nystagmography led us to diagnose vertigo caused by a central lesion. Subsequent MRI findings revealed a cerebello-pontine angle lesion as a metastatic tumor. The ratio of brain tumors, especially metastatic tumors, among vertigo patients is low. However, this case indicated that MRI might be useful for patients who have a past history of cancer.