Question: What is (are) Vein of Galen aneurysm ?
Answer: Vein of Galen aneurysm is a rare form of arteriovenous malformation in which a particular vein at the base of the brain, the vein of Galen, dilates causing too much blood to rush to the heart and leading to congestive heart failure. Sometimes the defect will be recognized on an ultrasound before birth, but most often it is seen in infants who experience rapid heart failure. In less severe cases, a child may develop hydrocephalus because the enlarged malformation blocks the normal flow or absorption of cerebrospinal fluid. Although the exact cause remains unknown, this condition appears to be a result of a defect in early fetal development.
Source: GARD

Question: What are the symptoms of Vein of Galen aneurysm ?
Answer: What are the signs and symptoms of Vein of Galen aneurysm? The Human Phenotype Ontology provides the following list of signs and symptoms for Vein of Galen aneurysm. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormality of the cerebral vasculature 90% Aneurysm 50% Peripheral arteriovenous fistula 50% The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD