Spontaneous thrombosis of a large vein of galen malformation.

A large vein of Galen was diagnosed in a 9-month-old boy. This was not treated at birth, as there was no associated congestive heart failure. The patient was followed conservatively and follow-up magnetic resonance imaging showed increase in the size of the vein of Galen malformation. Subsequent cerebral angiogram demonstrated hypertrophied but thrombosed right posterior choroidal artery, suggesting spontaneous thrombosis of the arterial feeder and thus the embolization was not pursued.