[The remote effects of brain tumors on cerebral blood flow as measured by single photon emission CT]

In order to assess the remote effects of supratentorial brain tumors, the cerebellar blood flow and cerebral blood flow of the symmetrical regions in the contralateral cerebral hemispheres were measured by single photon emission CT. Forty four patients with supratentorial brain tumors, such as gliomas, meningiomas and germ cell tumors etc., were included in this study. Contralateral cerebellar hypoperfusion (CCH) was exhibited in 51%, 18 of 35 unilateral brain tumors. Regarding tumor location, CCH was more correlated with frontoparietal lesions. The mean values of contralateral delta Cerebellar blood flows (delta CBFs) were lower than those of ipsilateral delta CeBFs, and also statistically, bilateral delta CeBFs significantly decreased. The greater the volume of lesions including peritumoral edemas, the lower the delta CeBF became. Among the 9 cases with obstructive hydrocephalus, the preoperative delta CeBFs which had decreased significantly, returned to normal postoperatively. Statistically, it seemed that there was no transcallosal suppression caused by unilateral brain tumors. However the delta rCBF of the mirror foci in postoperative patients decreased significantly. In conclusion, the remote effects on the cerebral blood flow, which are common in strokes cases, were demonstrated in many cases of supratentorial brain tumors and the occurrence of CCH was closely related to the frontoparietal lesion including the tumor and peritumoral edema. Also the mechanism of CCH was discussed with preference for a transneural suppression.