1. Teaching NeuroImage Sankalp Gokhale, MD and Daniel T. Laskowitz, MD Department of Medicine (Neurology) Duke University School of Medicine Durham, NC, 27710 sankalpsgokhale@gmail.com

2. Clinical Details 22 year old man presented with intractable progressive headaches over 2 months Neurological examination was normal Based on CT scan and MRI scan, pineal mass was diagnosed. Intra-operatively, a firm mass with apparent venous drainage was observed Digital subtraction arteriogram was normal Histology confirmed diagnosis of vein of Galen (VG) related thrombosed aneurysm

3. ABAB C CD

4. Figure Legend Top Panel A. (Left) Non Contrast CT scan showing hyperdense mass in pineal region B. (Right) T1 weighted post contrast MRI image shows minimal contrast enhancement Bottom Panel Digital subtraction angiogram demonstrating no arterial (C) (Left) or venous abnormalities (D)(Right) in the region of mass, implying thrombosed VG-aneurysm

5. References 1. Abe T, Matsumoto K, Kiyota K et al. Vein of Galen aneurysmal malformation in an adult: a case report. Surg Neurol; 1996:39-43. 2. Hoang S, Choudhri O, Edwards M, Guzman R et al. Vein of Galen malformation. Neurosurg Focus; 2009:27(5): 1-8