A three-year-old girl developed spastic diplegia to the right and irregular tonc-clonic movements. Phenobarbital was started because of suspected seizure activity. The Pediatric unit asked for brain MR imaging to investigate neurological symptoms. MR and diffusion tensor imaging showed a haemorrhagic vein of Galen aneurysmal malformation (choroidal type) that shifted the corticospinal tract fibres to one side and the corpus callosum was moved forward. Vein of Galen aneurysmal malformations (VGAM) are characterized by multiple arteriovenous connections draining into a markedly enlarged median draining vein. This ectatic vein is not the vein of Galen, but its embryonic precursor, the median prosencephalic vein of Markowski. During normal development, the posterior portion of the median prosencephalic vein persists as the vein of Galen, while its anterior portion regresses in parallel with the formation of the internal cerebral veins (ICV). With the advent of endovascular neurointerventional techniques, the prospects for successful treatment of these lesions, once dismal, are now much improved. MR and diffusion tensor imaging can help in diagnosis and to guide endovascular interventional procedures.