Spinal Intramedullary Arteriovenous Malformation Draining into the Petrosal and Straight Sinuses resulting in Intraventricular Hemorrhage

We report here on a 33-year-old man who presented with intraventricular hemorrhaging (IVH) into the fourth and third ventricles that was caused by a cervical intramedullary arteriovenous malformation. The patient suddenly suffered from occipitalgia, frequently vomited and had a deteriorating headache. Computed tomography (CT) revealed intracranial hemorrhaging in the fourth and third ventricles, and magnetic resonance (MR) angiography and CT angiography showed a vessel coursing ventral to the brainstem connecting to the superior petrosal sinus. We subsequently diagnosed dural arteriovenous fistula of the superior petrosal sinus and performed cerebral angiography. A six-vessel-study showed no dural AVF, but we found a venous structure draining into the petrosal sinus. Vertebral angiography was thus focused on the cervical region with the spinal arteriovenous malformation at the cervical levels 6 and 7. Selective angiography of the muscle branches of the right vertebral artery revealed an AVM nidus and draining veins of the anterior spinal, anterior medullary, lateral pontine, petrosal veins, as well as the superior petrosal sinus, lateral mesencephalic vein, posterior mesencephalic vein, and straight sinus. Although it was difficult to assume the exact position of the rupture, it is conceivable that the rupture occurred form the intracranial draining vein, and anterior medullary vein, which coursed closest to the orifices of the fourth ventricle. The unique clinical features of the present case were (1) fourth intraventricular hemorrhage which is usually caused by an aneurysm or vascular malformation in the posterior fossa, (2) the intracranial draining veins being connected to the petrosal sinus visualized by MRA and CT angiography, leading us to diagnose him with dural AVF, and (3) intraventricular hemorrhaging caused by the rupture from a draining vein in the posterior fossa of the cervical intramedullary AVM without accompanying intramedullary hemorrhaging.