Parkinsonism and dementia with acoustic neurinomas. Report of three cases.

Three cases of acoustic neurinoma with parkinsonism and dementia are reported. The characteristics of parkinsonism seen in these cases consisted of the rapid development of symptoms and symmetrical rigidity. In all cases there was a marked enlargement of the ventricular system and transient improvement in their mental states was observed following ventriculoperitoneal shunt or removal of the tumor. In an autopsy case there were no pathological findings in the cerebral cortex, basal ganglia, substantia nigra or pontine nuclei. It was concluded that parkinsonism and dementia in these patients were caused by chronic hydrocephalus due to the acoustic neurinomas.