These are abnormal connections between arteries and deep draining veins of the brain. The capillaries which normally connect arteries to veins and function to slow blood flow allowing for the drop off of oxygen and nutrients to the brain are missing. Since vein of Galen malformations lack capillaries, blood flow can be fast and this in turn increases the work of the heart. Blood drainage is towards a single deep draining vein which becomes markedly enlarged (vein of Galen aneurysm). The result can be heart failure. The high flow of blood can also interfere with the normal blood drainage of the brain potentially causing hydrocephalus or 'water on the brain'.
This rare malformation develops in utero. Most often these patients are newborns with congestive heart failure due to arterial-venous shunting of blood in the brain.
There are 3 categories of vein of Galen malformations:
This intra-cranial abnormality may be detected on prenatal ultrasound or MRI. After birth, this pulsatile flow can be detected by a transcranial doppler. If the neonate presents with heart failure, a cardiac echo will be done to establish the severity.
A MRI will be done to establish the venous and arterial vascular anatomy. The MRI will also assess the status of the surrounding brain, which may be abnormal secondary to ischemia or hemorrhage.
A MRA may be done to depict the arterial feeders and venous drainage pattern of the malformation.
An angiogram will be done if the patient requires embolization. This involves a small incision in the groin area and placing a small catheter in the femoral artery. This catheter is guided to the brain arteries and images are taken after x-ray contrast is injected in the catheter to assess the blood vessels. This test will show the vascular anatomy and the flow dynamics of the blood.
The management options, timing of intervention and potential complication make it imperative that this condition be recognized precisely and accurately and managed at an experienced center at the optimal moment in time in order to achieve a normally developing child. This should involve a team of specialists including a neurointerventional radiologist, neurosurgeon, and cardiologist.
If the neonate is in congestive heart failure, this should be treated first. A pediatric cardiologist may prescribe cardiac medications, oxygen therapy or even mechanical ventilation if severe.
Careful and frequent developmental assessments and MRIs are needed to recognize delays and early hydrocephalus. Treatment should be delayed if possible until at least 5 months of age.
This is difficult to treat using standard neurosurgical procedures. The treatment of choice is Embolization.
Embolization involves injection of a glue-like material through a catheter placed near the malformation in the brain. This treatment will decrease blood flow through the lesion and may immediately improve the heart failure. Often a patient will require more than one Embolization. Some patients may be cured by partial Embolization.
Many patients grow up completely normal after treatment. The risk of treatment varies but may be as high as 10% for permanent disabling stroke or death.