1.What is hydrocephalus? Hydrocephalus is a medical term. To understand what hydrocephalus is, we must first have an understanding of the cerebrospinal fluid circulation in normal people. There are cavities inside the human brain, which we call ventricles, filled with fluid secreted by the ventricles, which is clear and transparent and called cerebrospinal fluid. The cerebrospinal fluid is produced from the ventricles inside the brain and flows down certain channels to the surface of the brain and spinal cord, where it “soaks” them and serves to cushion the vibrations and nourish the nerves. The cerebrospinal fluid is secreted and absorbed every day, and a dynamic balance is achieved between the two. In patients with hydrocephalus, this balance is broken and the production is greater than the absorption, causing cerebrospinal fluid to accumulate in the cranial cavity, compressing the brain tissue and causing it to shrink and thin, resulting in a series of symptoms. 2. Is hydrocephalus congenital, and is hydrocephalus dangerous? Hydrocephalus is caused by congenital and also by acquired pathogenesis. Some people know that congenital hydrocephalus, the so-called “big head doll”, is born with a larger than normal head circumference, if not treated will soon die. In other cases, hydrocephalus is caused by trauma, intracranial hemorrhage due to congenital vascular malformation and impaired absorption of cerebrospinal fluid, or by tumors or parasites that block the channels for hydrocephalus circulation. In pediatric cases, congenital causes are the most common. As mentioned above, the danger of hydrocephalus is that it compresses the brain tissue, resulting in the normal brain function and the development of brain tissue being affected. 3.What are the symptoms of hydrocephalus and how to detect it early? The symptoms of hydrocephalus are abnormal enlargement of head circumference, enlarged and full fontanelle, exposed scalp “veins”, heavy head and difficult to support; if the increase of intracranial pressure is serious, the child is often restless, drowsy, loss of appetite, occasional vomiting or convulsions; if the time is longer, there will be growth retardation. The easiest way to first check is to measure the head circumference and compare it with normal developmental indicators: use a soft ruler to go around from between the eyebrows to the most prominent place at the back of the head, and the number of centimeters measured is the head circumference. Generally, the head circumference is around 38cm at 1 month, 40cm at 3 months, 43cm at 6 months, 46cm at 12 months and 48cm at 18 months, which can be used as an approximate reference. If there is any abnormality, you can go to the hospital for examination. The initial examination should be done by cranial CT to confirm if there is ventricular widening, and if there is hydrocephalus, a cranial magnetic resonance imaging (MRI) examination is needed to clarify the type and cause of hydrocephalus in order to decide the treatment plan. 4.How is hydrocephalus treated? The treatment of hydrocephalus is mainly surgical treatment, especially for the fast progressing hydrocephalus, surgery should be considered. If there is a clear cause, the corresponding cause should be treated first, such as brain tumor, the tumor should be removed to eliminate hydrocephalus, if the hydrocephalus is congenital or caused by intracranial hemorrhage, the current general use of cerebrospinal fluid shunt, which is buried under the skin of the catheter to drain the cerebrospinal fluid to other parts of the body to promote absorption, such as: the abdominal cavity, the right atrium, etc., the most commonly used is the lateral ventricle ventral shunt, which drains excess cerebrospinal fluid into the abdominal cavity, which has a strong function of absorbing fluid and can absorb the fluid back into the body for reuse. 5.How effective are the various methods of treating hydrocephalus and are they risky? As far as the various methods of treating hydrocephalus are concerned, there is no absolutely safe solution. With the understanding of the pathophysiology of hydrocephalus and the advancement of material science, the treatment effect of hydrocephalus has been significantly improved compared with before. The use of anti-reflux, adjustable valves and antibacterial tubes has significantly reduced the chance of postoperative complications of hydrocephalus, but because of the limitation of high price (about 50,000 yuan per set of shunt equipment), it is not widely used. The main problems after pediatric hydrocephalus shunts are: intracranial infection, shunt blockage, excessive and insufficient shunts, and the need to replace shunts as they grow older. According to our experience in recent years, as long as the indications for surgery are strictly grasped and the principles of surgical essentials and aseptic operation are mastered, the incidence of the most serious complications, intracranial infection and catheter blockage, is not high, and shunt underflow and shunt overflow can be solved after the application of adjustable valves.