[Spontaneously thrombosed aneurysm of the vein of Galen: a case report].

A 13-year-old girl was admitted with headache of sudden onset. Neurological examination did not reveal any abnormalities on admission. Her growth and development were normal. CT scan showed a high density mass in the pineal region without contrast enhancement. It was a spontaneously thrombosed aneurysm of the vein of Galen associated with thrombosis of the straight and the transverse sinuses on MRI. Moreover, there were an interhemispheric lipoma and a right temporal arachnoid cyst. The superior sagittal, bilateral transverse, sigmoid and straight sinuses were not opacified but unusual pathways of various venous channels were demonstrated on angiograms. Persistent fetal drainage remained as the collateral venous pathways such as the ventral diencephalic and striate veins and the paired longitudinal head sinuses. There were two types of unusual deep venous pathways. The left internal cerebral vein drained into the left ventral diencephalic vein. The left ventral diencephalic vein drained through the left lateral mesencephalic and ponto-medullary veins into the spinal venous plexi. The dilated striate veins drained into the deep middle cerebral veins through the cerebral parenchyma. Mainly, there were three types of superficial venous pathways. The paired longitudinal head sinuses drained into the emissary veins at the ethmoid sinus in retrograde fashion, and finally into the nasal mucosa. The superficial cerebral veins drained into the cavernous sinus which communicated with the nasal mucosa and the pterygoid plexi. The veins of the posterior fossa drained into the occipital emissary veins. After being admitted, the patient had remarkable nasal bleeding which was difficult to stop. This symptom seemed to be related to the collateral venous drainage to the nasal mucosa shown on angiograms. Finally, she became completely asymptomatic three weeks after admission.