The dilatation of the lateral ventricles is a sign of hydrocephalus, which causes enlargement and expansion of the ventricles. The degree of dilatation of the lateral ventricles varies from mild to severe and needs to be determined by cranial CT and cranial MRI. If the test shows mild dilatation and no other abnormalities, it is a mild hydrocephalus, which has no impact on health and does not require treatment. If the widening of the lateral ventricles is very serious, it is a severe hydrocephalus, which can lead to low brain function and cause mental retardation and slow reaction time. The treatment can be chosen according to the specific condition. If the test is traffic hydrocephalus with full ventricular widening, ventriculoperitoneal shunt surgery can be performed. If it is obstructive hydrocephalus with tumor or cyst or vascular malformation, the primary disease needs to be treated actively first, and if the primary disease cannot be found, it can be treated with a third ventriculostomy.