A baby with a large head is not necessarily hydrocephalus. The enlarged head due to hydrocephalus has the following characteristics: 1. Progressive enlargement: normal infants have a monthly increase in head circumference of about 1.2-1.3 cm at the earliest 6 months of age, and when suffering from hydrocephalus, the head circumference grows 2-3 times faster; 2. Developmental delay: the development of the affected child lags behind that of children of the same age, and some children with hydrocephalus have a larger head. In addition, there are more children with hydrocephalus whose heads are not very large. Only when hydrocephalus occurs before the fontanelle closes in children, and when the hydrocephalus develops more rapidly, the head will increase in size. The diagnosis of hydrocephalus in infants needs to be confirmed by CT or MRI. Some cases of hydrocephalus caused by cerebral hypoplasia, relatively increased cerebrospinal fluid, secondary to other diseases, or those that occur after the closure of fontanelle do not show cranial enlargement. The symptoms vary with the age of onset of the infant and are mainly irritability, growth retardation, headache, vomiting, nausea, lethargy, and seizures. Signs include enlarged head circumference, high fontanelle tone, difficulty with upward vision, optic papilla edema, and abducens nerve palsy.