Cerebellar hemorrhage due to dural arteriovenous fistula mimicking a hemorrhagic metastatic brain tumor: a case report

Abstract

We report a rare case of posterior fossa dural arteriovenous fistula (AVF) presenting as cerebellar hemorrhage with a substantial brain edema. A 75-year-old man presented with imbalance and gait disturbance. He had a 5-year-old history of malignant melanoma of the toe, which was successfully resected and has not recurred ever since. He visited a neurosurgical clinic, but was transferred to our hospital because of his cerebellar dysfunction. Magnetic resonance (MR) images revealed a right tonsillar T2 high-intensity lesion with a small hemorrhage. However, diffusion-weighted images did not suggest any diffusion impairment. Contrast-enhanced MR images revealed an enhanced lesion on the right tonsil. Accordingly, he was diagnosed with a metastatic brain tumor of malignant melanoma, and corticosteroids were administered. One week after the admission, T2 high-intensity area of the right tonsil decreased, the enhanced area shrunk, and his cerebellar symptoms improved. Cerebral angiography demonstrated dural arteriovenous shunt on the tentorium cerebelli between the posterior meningeal branch of the vertebral artery and the right inferior vermian vein. Dural AVF comprised retrograde leptomeningeal venous drainage without draining into the dural sinus. Thus, we could diagnose cerebellar hemorrhage due to dural AVF of the posterior fossa. The abnormal vessels disappeared 3 months after the admission. Hence, this report suggests that tonsillar hemorrhage and diffuse cerebellar edema may indicate the presence of dural AVF, considering a distinctive draining pattern of the cerebellar tonsil.