The pathogenesis of Horner’s syndrome is mainly due to the compression or damage of the sympathetic pathway from the neck to the eye by various factors, resulting in abnormalities in the normal function of the sympathetic nerves in the corresponding area. The diagnosis is usually made on the basis of the three main symptoms of constriction, ptosis and entropion and the clinical history. For patients with less obvious symptoms, CT examination can be performed to assist in confirming the diagnosis, which is generally divided into plain scan, contrast-enhanced scan and contrast scan. The CT examination methods for Horner syndrome are as follows: 1. Plain scan Plain scan is a general scan without contrast enhancement or contrast. Generally, plain scan is performed first. 2.Contrast-enhanced scan Contrast-enhanced scan is a method of scanning after injecting water-soluble organic iodine agent, such as 60ml of 60%-76% pantothenic glucosamine, through the vein. When the concentration of iodine in the blood increases, the concentration of iodine in the organ and the lesion can be different, forming a density difference, which may make the lesion more clearly visible. The method is divided into group injection method, static drip method and static injection and static drip method. 3.Contrast scan Contrast scan is a method of making a contrast of an organ or structure first and then scanning it. For example, injecting 8~10ml of iodotrigine or 4~6ml of air into the brain pool for brain pool imaging and then scanning, which is called brain pool imaging CT scan, can clearly show the brain pool and the small tumor in it.