Vein of Galen Aneurismal Malformation

A 30-year-old patient came in for routine scanning for fetal well being. Prenatal scan showed a cystic mass in midline between lateral ventricles. Bilateral lateral ventricles were mildly dilated.

Figure 1: Mild line cystic mass

Figure 2: Mild line cystic mass

Figure 3: mild hydrocephalus

Figure 4: Color Doppler shows backwards flow in cystic mass.

Figure 5: Multiple tortuous feeder vessels

Color Doppler scan showed flow in cystic mass backwards towards confluence of sinuses. There were multiple tortuous feeding vessels. High velocity flow was seen on pulsed Doppler examination.

Fetal echocardiography showed slight cardiomegaly and slightly distended superior cava, brachiocephalic, and internal jugular veins, no hydrops seen.No other congenital anomaly found.

Discussion: Rare arteriovenous malformation of the central nervous system characterized by a high venous flow.

Types: 1) arteriovenous fistula, 2) arteriovenous malformation with ectasia of the vein of Galen and 3) varix of the vein of Galen.

Pathogenesis: Aneurysmal dilation with arteriovenous fistula. Results from immaturity of the cerebral vascular system with persistence of fetal vessel. It actually involves median prosencephalic vein of Markowski. Develops between seven and 12 weeks of fetal development when the median prosencephalic vein drains the large choroid plexuses.

Diagnosis: Midline cystic mass in the pineal region of the brain with high velocity flow on Doppler examination. Size depends on volume of shunt.

Associated anomalies: Hydrocephalus, non-immune hydrops and porencephaly.

Differential diagnosis:

• Arachnoid cyst
• Porencephalic cyst
• Choroid plexus cyst
• Choroid papilloma
• Teratoma
• Congenital dural arteriovenous fistula

Prognosis: Poor when cardiac failure and hydrops is present; Treatment : embolization

Harpreet Singh, MD, JP Scan private diagnostic center, Khanna, Punjab, India