(1) Clinical manifestations: a: The head circumference of the newborn increases rapidly after birth, the head becomes round, the subcutaneous veins become angry, the fontanelle enlarges and bulges, the tension is high, and the fontanelle is not depressed when the child is placed in an upright position. b: The cranial sutures separate, the head becomes round, and the skull becomes thin. The enlargement of the head is mainly seen in the upper part of the cerebellar curtain, and the posterior cranial fossa is especially enlarged if the fourth ventricle is occluded (normal value of head circumference: the head circumference of newborns is 33-35cm, and the head circumference increases about 1.2-1.3cm per month within 6 months, 8cm in total, 3cm in the second half of the year, 2cm in the second year, and 2cm in the third and fourth year. (The posterior fontanelle closes in 6 months after birth, and the anterior fontanelle closes in 9-18 months) Infants and young children with congenital hydrocephalus mostly begin to enlarge their skulls a few weeks after birth, usually after 3-5 months, but there are also those whose skulls are enlarged at birth. Disproportionate frontal protrusion, downward pressure on the orbital roof, downward vision of both eyeballs, downward turning of the eyeballs, whitening of the upper part of the sclera, enlargement of the fontanelle and increased tension, other fontanelles can also be enlarged, separation of the skull sutures, expansion of the scalp veins, “broken pot sound” on cranial percussion, the sutures are not closed in infants and young children, when the intracranial pressure increases, the skull can occur compensatory The symptoms are repeated vomiting, brain degeneration, brain developmental disorders, central paralysis of the limbs, especially the lower limbs, often with intellectual changes and developmental disorders, optic nerve compression and atrophy, which can lead to blindness, nystagmus, convulsions are also more common, and other parts of the body are often complicated by deformities.