Hydrocephalus can be divided by location into intraventricular hydrocephalus and extraventricular hydrocephalus. The latter is called ExternalHydrocephalus (EH). It occurs mainly in infancy and early childhood and only in children whose fontanelles are not closed. All factors that cause damage to the central nervous system during the perinatal period can lead to external hydrocephalus. These include asphyxia, obstructed labor, preterm birth, intracranial hemorrhage, and neonatal hyperbilirubinemia. Cranial trauma and infection are also important causes, as are lung infections and vitamin A toxicity or deficiency. Nearly 50% of children with external hydrocephalus have normal growth and development, but about half of them have various degrees of abnormalities or neurological sequelae during their growth and development. Severe ones include: paralysis, retarded intellectual development, and epilepsy. Less severe ones include: delayed motor development, transient convulsive seizures, febrile convulsions, retarded speech development, lack of weight gain, difficulty feeding, excitability, irritability, hyperactivity, difficulty concentrating, and learning difficulties or disorders. However, in general, the most common are: motor developmental delay, speech developmental delay, and behavioral problems. Most external hydrocephalus can be detected before the age of half a year, but a head CT or head ultrasound before 2 months of age does not necessarily mean that external hydrocephalus is present. If the following conditions are found, you should be alert: 1. crying, excitement, agitation, shrieking and jumping. 2. Restless sleep, easy to wake up, difficulty in falling asleep, short duration of sleep, total sleep time <15 hours per day. 3. Difficulty in feeding, poor sucking, easy to spit up milk. Although the above manifestations are not necessarily external hydrocephalus, they may affect the future mental and psychological development of the infant. If the following conditions are found during the development process, the following should also be alerted: 1. head circumference is larger than normal for infants of the same age or head circumference increases quickly, fontanelle is large or closes late. 2. 2. Poor reaction, sluggishness, poor arm and leg movement, and no response to sound and color. 3. The body is stiff and straight or light and weak. The diagnosis of external hydrocephalus mainly relies on head CT and head magnetic resonance imaging (MRI). And head CT is the main method to diagnose external hydrocephalus at present, and its price is comparable and the image is clear, which can meet the requirements of diagnosis. The detection of external hydrocephalus lies in the early detection of parents by careful observation and timely consultation and examination with a specialist if any abnormality is found. Because severe external hydrocephalus can compress brain tissue and various etiologies can produce neurological damage, active treatment is necessary Generally speaking, treatment before the age of half is most effective. There are two main aspects of treatment: first, treatment of the abnormalities found, such as startle, agitation, convulsions, paralysis, etc. The second is the preventive treatment of future abnormalities that may occur during development, such as delayed motor development compared to the same age, failure to call father and mother at 15 months or unclear pronunciation, etc. Early intervention is needed to ensure normal growth and development in the future. The method and duration of treatment will depend on the condition of the child. For mild to moderate dysfunction or developmental abnormalities, treatment is required for more than 1-3 months. Most of the cases can be treated at home under the guidance of a physician, with regular outpatient follow-ups, unless the physician recommends inpatient treatment. As the cause is removed, the cranial brain continues to develop and the cranial suture closes, most of the external hydrocephalus can recover on its own, but 30-40% of the patients may have motor retardation, specific motor skill disorders, backward language development, learning difficulties, behavioral disorders (such as hyperactivity, difficulty concentrating, impulsivity, disobedience, etc.), and only a very small number may have serious neurological sequelae such as paralysis, epilepsy, mental retardation, etc. The sequelae of the disease may be severe, such as paralysis, epilepsy and mental retardation.