Acoustic Neurinoma with Early Venous Drainage and Caput Medusae-like Vasculature on Angiogram

Abstract

It has been considered that acoustic neurinomas are hypovascular tumors on angiogram. Recent angiographical analysis, however, revealed that some of them showed tumor stain, capsular stain, and even arteriovenous shunt. The problem with operation on the acoustic neurinoma with a peculiar vasculature on angiogram has not been discussed in previous reports. In this paper, the neuroradiological findings of a unique case are described, in conjunction with the operative problem. A case of huge acoustic neurinoma with early venous drainage and caput medusae-like vasculature on angiogram is presented. The patient was a 46-year-old woman suffering from dizziness and gait disturbance. On admission, she had bilateral choked disc, left fifth and seventh nerve palsy, and left cerebellar signs. The audiogram showed scale out on the left, carolic test and auditory brain stem response were nil on the left side. On computed tomography, a huge, heterogeneously enhanced mass was detected in the left cerebellopontine angle. Vertebral angiography revealed that the tumor was supplied by the anterior inferior cerebellar artery and ascending pharyngeal artery. Caput medusae-like vasculature was visualized in arterial and capillary phases, and abnormal draining veins were also opacified in these phases. They were considered to be an arteriovenous fistula. At operation, the abnormal vasculature looked like an arteriovenous malformation on the tumor capsule, which made the surgical procedure of dissecting the tumor from the pons extremely difficult.