It is commonly believed that in vein of Galen aneurysmal malformations (VGAMs) venous structures normally constituting the deep or Galenic venous system, such as the internal cerebral vein (ICV) and the basal vein of Rosenthal, are not connected to the vein of Galen. In this report, the authors describe 2 cases of successfully treated VGAM in which drainage of an ICV into the vein of Galen was confirmed by follow-up angiography. Two mural types of VGAM were treated using transarterial glue embolization when 1 child was 5 months and the other was 6 months old. The postoperative outcomes for these babies were complete cures. Follow-up digital subtraction angiography obtained after 12 months (Case 1) and 6 months (Case 2) confirmed that the shrunken median prosencephalic vein connects with the deep venous system. The possibility of normal deep Galenic venous drainage must be considered in endovascular management of VGAM. The goal of endovascular intervention is to close only the ventral component of the dilated median prosencephalic vein.