Reduction of blood flow in the brain stem and cerebellum caused by petroclival tumors.

Blood flow in the brain stem (BSBF) and cerebellum (CerBF) was investigated by positron emission tomography in 12 patients with petroclival tumors (study group) and 14 healthy volunteers (control group). (15)O-labeled water was used as the radioisotope tracer. BSBF and ipsilateral CerBF were significantly lower in the study group compared with the control group (p < 0.005). Five of 12 patients in the study group exhibited more than 20% reduction of CerBF ipsilateral to the tumor, whereas no such asymmetry was disclosed in any subject in the control group (p < 0.01). Sex, age, and tumor histology had no statistically significant association with the level of BSBF. Ipsilateral CerBF was significantly lower in patients with vestibular schwannomas, compared to those with sphenopetroclival meningiomas (p < 0.025). No statistically significant association between BSBF and the type of postoperative course was found, whereas four of the five patients with more than 20% reduction of CerBF ipsilateral to the tumor had prominently increased cerebellar ataxia after removal of the neoplasm. Preoperative investigation of the cerebral blood flow may be important for the prediction of outcome after surgical resection of petroclival tumors.