[Influence of cerebellopontine angle tumor on cerebellar circulation--possibility of remote effect to the cerebellum].

Nine cases (4 men and 5 women, ranging in age from 39 to 73 years with a mean age of 51 years) of cerebello-pontine angle tumors were evaluated by cerebral blood flow scintigraphy on the basis of clinico-functional anatomy. In the 4 of 5 cases in which the middle cerebellar peduncle was compressed by the mass, definite hypoperfusion was revealed in the ipsilateral cerebellar hemisphere. On the other hand, in the 3 of 4 cases without compression of the middle cerebellar peduncle, no asymmetric perfusion was seen in either the right or left cerebellar hemisphere. There were neither supratentorial lesions nor signs of increased intracranial pressure in any of the 9 cases. On the vertebral angiograms of the 4 cases with compression of the middle cerebellar peduncle, non-opacification of the ipsilateral anterior inferior cerebellar artery occurred in only one case. There were no definite signs of reduction of cerebellar blood flow in the other 3 cases. The middle cerebellar peduncle is one of the largest bundles of centripetal fibers in the cerebellar hemispheres. Secondary neuronal fibers of the corticopontocerebellar pathway are the most prominent among these fibers. The mass lesion in the cerebellopontine cistern has a tendency to compress the middle cerebellar peduncle and may deactivate the corticopontocerebellar pathway even if it is small.(ABSTRACT TRUNCATED AT 250 WORDS)