1.Congenital developmental abnormality: subcerebellar tonsillar hernia, flat skull base, hydrocephalus, etc. are the most common causes. Abnormal cerebrospinal fluid dynamics: congenital occlusion at the exit of the fourth ventricle obstructs the normal circulation of cerebrospinal fluid, and the pressure is transmitted to the spinal cord, resulting in dilatation of the central canal of the spinal cord. 3.Abnormal blood circulation: spinal cord vascular malformation, tumor cystic degeneration, inflammation, ischemia, necrosis, etc. cause blood circulation obstruction resulting in softening and dilatation of the central canal. Surgical treatment of spinal cord cavernous one of the methods, need to choose different types of surgery according to the cause of the disease.