POSTERIOR-FOSSA VENOUS ANGIOMAS WITH DRAINAGE THROUGH THE BRAIN-STEM

PURPOSE: To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem. METHODS: Eleven cases of posterior fo ssa Venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the ce rebellum and brain stem is made. RESULTS: Six of the 11 venous angioma s were found in the cerebellum, four in the brain stem; one involved b oth the cerebellum and brain stem. The cerebellar venous angiomas drai ned to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transponti ne vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases. CONCLUSION: Cerebellar and brain s tem Venous angiomas have several potential routes of drainage, includi ng an enlarged Vein traversing the pons, midbrain, or medulla. A knowl edge of the normal Venous anatomy of this region helps to understand t he occurrence of these uncommon routes of venous drainage.