The white matter of the brain is the part of the brain where nerve fibers gather, mainly in contrast to the gray matter of the brain, and is also called the white matter of the brain because it is lighter than the color of the cerebral cortex. The main function is to transmit nerve impulses. In head CT examination, the density of the white matter of the brain is slightly lower than that of the gray matter of the brain, and the signal of the white matter of the brain in head MRI examination is long t1 and long t2 signal shadow. The most common cause of cerebral white matter disease is the tendency to demyelination of cerebral white matter, and the causes are complex, including genetic factors, cerebral ischemia, hypoxia, poisoning, infection, etc. The most common cerebral white matter lesion is caused by cerebral atherosclerosis and cerebral vascular stenosis.