[A case of cerebellar hematoma due to venous angioma presenting trigeminal dysfunction].

With regard to the natural history of venous angioma, the risk of hemorrhage is reported to be relatively higher if the lesion exists in the posterior fossa. However a recent report of 100 cases of venous angioma concluded that the risk of hemorrhage was low, being only 0.22%/year. Although the true rate of hemorrhage is uncertain, we have encountered case of cerebellar hematoma due to venous angioma in the posterior fossa where the patient presented with trigeminal dysfunction and cerebellar ataxia, without any history of hypertension. We considered that venous angioma in the posterior fossa might cause cerebellar hemorrhage. After removal of the hematoma, the patient's symptoms were resolved. In the posterior fossa, a relatively higher volume of venous blood would cause venous congestion to occur more easily, leading to damage of the fragile wall of the angioma.