The human brain and spinal cord are immersed in water, which is called cerebrospinal fluid. Without cerebrospinal fluid, nerve cells would die and the brain and spinal cord would not survive. The storage system for cerebrospinal fluid includes the ventricles (lateral ventricles, third ventricle, fourth ventricle, etc.), the subarachnoid space, and the brain pools in the surface space of the brain. The cerebrospinal fluid is not a pool of stagnant water, but a flowing “river” (medically known as the cerebrospinal fluid circulation). This “river” brings some of the nutrients to the nerve cells and carries away some of the metabolic waste. The source of the “river” is the intracerebroventricular plexus, and more than 80% of the water is produced by the plexus in the lateral ventricles, producing about 500 ml of water per day in normal adults. The mainstream pathway of water is: water produced by the choroid plexus in the lateral ventricle → the third ventricle → the midbrain aqueduct → the fourth ventricle → the subarachnoid space and brain pool → the arachnoid granules on the brain surface → venous blood. Cerebrospinal fluid is absorbed into the blood at the arachnoid granules. Etiology of hydrocephalus If there is too much cerebrospinal fluid in the ventricles, hydrocephalus forms, which appears as enlarged ventricles (lateral ventricles, third ventricle, and/or fourth ventricle) on images such as CT and MRI. From the above pathways, it can be inferred that the possible causes of hydrocephalus are: 1) excessive water production from the choroid plexus; 2) obstruction of the pathways; and 3) inability of the arachnoid granules to absorb water. Types of hydrocephalus Two types of hydrocephalus are common in clinical practice: 1) obstructive hydrocephalus (obstruction of the cerebrospinal fluid circulation pathway, most commonly due to obstruction of the aqueduct caused by tumors and inflammation of the aqueduct, followed by obstruction of the opening of the four ventricles) and 2) traffic hydrocephalus (obstruction of the arachnoid granules causing water not to be absorbed into the bloodstream). The common symptoms of hydrocephalus Because the choroid plexus produces water is not controlled by the smooth circulation of water, if the water produced can not flow out or be absorbed, it will lead to excessive water in the ventricles, more water will lead to increased intracranial pressure, the patient will have headache, nausea and vomiting, vision loss, etc., which is common in patients with short-term hydrocephalus (usually within 1 month); and long chronic hydrocephalus intracranial pressure increases slowly In the case of chronic hydrocephalus, the patient’s performance is memory and mental deterioration, gradual unsteadiness in walking, incontinence, etc. Treatment of hydrocephalus I. Obstructive hydrocephalus: 1. Triple ventriculostomy: a new procedure that has emerged in recent years. If the cerebrospinal fluid circulation pathway is obstructed, an artificial opening is made at the bottom of the three ventricles (mostly non-functional membranes) so that cerebrospinal fluid can flow into the subarachnoid space through this opening and be absorbed by the arachnoid granules, thus achieving the purpose of treatment. This procedure is the most suitable for the physiology of the patient, and has become the preferred procedure for obstructive hydrocephalus internationally. 2.Ventriculoperitoneal shunt: for patients with traffic hydrocephalus with impaired absorption of cerebrospinal fluid, cerebrospinal fluid is introduced into the abdominal cavity through an artificial tube, so that the water is absorbed in the abdominal cavity; traffic hydrocephalus is more likely to use this procedure; the requirements for the shunt tube are high; 3.Ventriculoperitoneal atrial shunt: long-term postoperative anticoagulation and more complications are required, so it is now used less; 4.Intravertebral arachnoid Subarachnoid-abdominal shunt: more complications, less used. 5.Ventriculo-occipital pool drainage: it is very traumatic and has been abandoned after the emergence of ventriculoscopic triple ventriculostomy; 6.Lateral intraventricular choroid plexus electrocautery: the effect is uncertain. There is another kind of benign hydrocephalus with enlarged ventricles, but the intracranial pressure is in the normal range, and it is controversial whether to treat it or not.