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The cerebellum is a crucial structure for cognitive function as well as motor control. Benign brain tumors such as schwannomas, meningiomas, and epidermoids tend to occur in the cerebellopontine angle cisterns and may cause compression of the posterior lateral cerebellum near the superior posterior fissure, where the eloquent area for cognitive function was recently identified. The present study examined cognitive impairment in patients with benign cerebellar tumors before and after surgical intervention in order to clarify the functional implications of this region in humans. Patients with cerebellar tumors showed deficits in psychomotor speed and working memory compared with healthy controls. Moreover, these impairments were more pronounced in patients with right cerebellar tumors. Functional magnetic resonance imaging during performance of a lure task also demonstrated that cerebellar tumors affected pattern separation or the ability to distinguish similar experiences of episodic memory or events with discrete, non-overlapping representations, which is one of the important cognitive functions related to the hippocampus. The present findings indicate that compression of the human posterior lateral cerebellum affects hippocampal memory function. [ABSTRACT FROM AUTHOR]

Abstract: Background: Nobody knows whether cognitive dysfunction affects survival. Furthermore, it is unknown whether the dysfunction is caused by the tumor itself or by its treatment. Methods: Patients with 20 gliomas (LGG, 7; MG, 13 [AG, 4; GM, 9]) in the right brain (nondominant) and 11 gliomas (LGG, 1; MG, 10 [AG, 6; GM, 4]) in the left brain (dominant) were studied. Thirty-four patients with meningioma were also studied. Cognitive function was evaluated by the 3MS examination, and propriety of radical resection of tumor was reviewed. Results: Cognitive function pre-Op and post-Op was normal in patients with LGG and MGs in the right brain but decreased before an Op in all patients with MG in the left brain, and they did not normalize after Op. In patients with MG in left brain, the test of temporal and spatial orientation, first recall, similarities, 4-legged animals, mental reversal, and writing decreased after Op. Cognitive hypofunction before or after Op did not correlate with tumor malignancy and degree of tumor resection. Conclusion: Firstly, radical Op should aim at improvement of cognitive function for patients with glioma in the right brain, and for patients with glioma in the left brain, QOL should be thought about without expecting improvement of cognitive function. Secondly, improvement of cognitive function cannot be anticipated in patients with meningioma in the left brain. Aged patients older than 75 years require carefulness in Op. Then, damage of the cingulated gyrus and corpus callosum should be avoided in the left brain. This study emphasizes that clinicians should be careful in the evaluation of cognitive function in glioma and meningioma treatment. [Copyright &y& Elsevier]