VEIN OF GALEN MALFORMATION: ANESTHESIA CONCERNS

▶️Vein Of Galen Malformation (VOGM) is a dilatation of the median vein of the procencephalon (which is a precursor of the Vein of Galen), caused by an arterio venous (A-V) shunt from the choroidal arteries of the anterior and posterior circulation. It can cause  A-V shunting and related systemic effects and hydrocephalus. 

▶️Incidence is less than 1% of cerebral vascular malformations.

▶️PROBLEMS:

✔️Most of the issues are due to the effect of A-V shunting

✔️Congestive Cardiac Failure and Pulmonary Hypertension : Due to A-V shunting . The etiology of cardiac failure may begin in utero. High output cardiac failure is associated with VGAM because 60 to 80% of aortic blood flow is directed through the VGAMS low resistant shunt. Blood flow travels through the VGAM during diastole creating a steal phenomenon. The reduction of diastolic pressure can lead to myocardial ischemia secondary to reduced coronary blood flow. 

 ✔️Ventriculomegaly : A-V shunting --> increased dural sinus pressure --> resistance to CSF entry to the sinus --> enlargement of ventricles

✔️Seizures

▶️INDICATIONS FOR DEFINITIVE MANAGEMENT: CCF, Hydrocephalus , Neurological symptoms

▶️TREATMENT

✔️Main goal of the treatment is to control the A-V shunt

✔️Endovascular embolization is the preferred treatment; other option is surgical clipping.

✔️Embolization of the feeding arteries and draining veins can result in reduction of blood flow through the VOGM which is the key to improved cardiac function and brain injury prevention.

✔️Embolization is less invasive and has a higher survival rate than open neurosurgical procedures. It provides better hemodynamic stability with minimal pain. Heart failure is an indication for urgent embolization. 

▶️ANESTHESIA CONCERNS

✔️Improving the cardiac function is the key to avoid multiple organ failure. The mortality rate for all neonates in heart failure undergoing transcatheter embolization can be up to 50%, mortality is much higher when pulmonary hypertension is present.

✔️Cardiac failure is difficult to treat and most beta agonists along with diuretics and Milrinone have been used with varying success. Although total systemic vascular resistance is reduced through the VOGM, the child in cardiac failure has an increased extracranial vascular resistance. So interventions that reduces extracranial systemic resistance is likely to improve systemic perfusion. Nitric oxide has been used to treat pulmonary hypertension in these patients.

✔️The goal is to achieve partial embolization with the endpoint of improving heart failure. So, the embolization may be staged. Each session is limited by the volume of contrast media delivered and the patient’s tolerance of the procedure. The ultimate goal of these sessions is to completely occlude the VOGM while avoiding neurological and cardiac injury

✔️Intracerebral hemorrhage due to venous hypertension is a potentially fatal complication of endovascular management. There is a thought that this complication can be avoided by staging the embolization procedure. Perforation of the venous sac can usually be managed by reversal of anticoagulation and continuation of coil embolization. Ischemic neurological deficits, Pulmonary embolization with embolic agents ( due to the high flow across the intracranial shunt that drains immediately into the central venous system) are other concerns. 

Reference: 

Anesthetic Implications of Neonatal Vein of Galen Aneurysmal Malformation (VGAM)  Ira S Landsman, Than Nguyen