Hydrocephalus brings great inconvenience to the life and work of patients. Do you know how to diagnose hydrocephalus? Hydrocephalus is a phenomenon of increased volume of cerebrospinal fluid in the skull, which has a huge impact on patients’ health and often leads to mental decline or symptoms of dementia. Therefore, it must be treated promptly after symptoms are found to avoid aggravation and increased harm. Diagnosis of hydrocephalus under normal pressure: 1, MRI : It can distinguish flowing cerebrospinal fluid from resting cerebrospinal fluid, and by measuring the flow rate of cerebrospinal fluid through the conduit to distinguish conduit obstruction or traffic, atrophic ventricular enlargement or hydrocephalic ventricular enlargement, etc. 2.CT: It can show the size of the ventricles, the degree of cortical atrophy and the related lesions. In normal pressure hydrocephalus, the ventricles are obviously enlarged and the sulcus is deepened at the same time, but the two are disproportionate, and the enlargement of the ventricles is more obvious. In some patients, periventricular hypodensity is an important manifestation. 3.Lumbar puncture: Cerebrospinal fluid pressure is below 180 mmH 2 O in the lateral position, and the patient’s symptoms and signs often improve temporarily after lumbar puncture. 4, continuous intracranial pressure tracing: continuous monitoring of intracranial pressure for 48 to 72 hours, two kinds of pressure changes can be found. One kind of pressure is basically stable with little fluctuation, and the average intracranial pressure is within the normal range; the other kind of intracranial pressure can be seen to have paroxysmal elevation in the form of jagged high waves or plateau waves, accounting for about 10% of the pressure measurement time, and the intracranial pressure is often at the upper boundary of normal or mildly elevated in the rest of the time. The latter is clinically effective for surgical treatment. 5.Isotope brain pool scan: Through lumbar puncture, radionuclide is injected into the subarachnoid space and brain scans are performed at 4, 24, 48 and 72 hours. Under normal conditions, the isotope flows on the convex surface of the brain without entering the ventricles, and the isotope disappears completely from the surface of the brain after 48 hours. In patients with primary normal pressure hydrocephalus, isotopes enter the ventricles and remain there for up to 72 hours without accumulation on the convex surface of the brain. Or the isotope enters the ventricles and also accumulates on the convex surface of the brain.