In general, if there is no spinal cord hollowing and the symptoms are not obvious, it can be treated without treatment. If there is hollowing, or if there are obvious symptoms such as headache, dizziness, unstable walking, hydrocephalus, etc., surgical treatment should be considered. Posterior cranial fossa decompression Posterior cranial fossa decompression has a therapeutic effect on the disease is a relatively unanimous view, and a large number of follow-up studies have concluded that posterior cranial fossa decompression is accompanied by improvement in clinical symptoms and collapse or reduction in diameter of the cavity on the imaging, and MRI cerebrospinal fluid hydrodynamic studies have also confirmed that the flow of cerebrospinal fluid in the occipital pool has improved significantly. 1. Bone decompression (1) Expanded decompression A median posterior occipital incision is made to expose the occipital bone scales, C1 to C2, and occlude the occipital bone scales 5 cm × 7 cm and the posterior arch of C1. The width of the occipital foramen posterior margin and posterior atlantoaxial arch is not more than 2.5 cm, but the cerebellum is likely to droop, forming pseudocephaly and causing strain on the midbrain. (2) Small-scale posterior cranial fossa decompression In response to the above-mentioned drawbacks, many scholars bite off the occipital scales 3 cm × 4 cm of the posterior cranial fossa decompression can also achieve good results, the focus of surgery should be on how to establish a smooth cerebrospinal fluid circulation pathway (such as opening the dura, cerebellar tonsillectomy to release the arachnoid adhesions, etc.). (3) Expanded repair of the skull Expanded repair of the posterior cranial fossa after bony decompression of the occipital scales, including autologous bone graft or artificial repair materials (methyl methacrylate, titanium plate, etc.), has satisfactory results. Although the scope of posterior cranial fossa bony decompression is still debated, this procedure is the ideal way to fundamentally solve the congenital bony posterior cranial fossa volume reduction of Chiari malformation and make it conform to the physiological shape. 2.Dural decompression There are different opinions on whether to open the dura and whether the dura should be enlarged for repair. (1) Open dura means that after biting off the skull according to one of the above methods, the dura of the posterior cranial fossa is cut open without sutures, and only the muscles and subcutaneous layers are tightly sutured. Due to many postoperative complications. It is not used basically. (2) For infants and young children, because the dura is more stretchable than that of adults, simple bony decompression of the posterior cranial fossa without dural repair can still achieve good results. (3) Expanded dural repair After cutting the dura (spinal) membrane in “Y” shape, the dura of the posterior cranial fossa is expanded and repaired with autologous fascia or artificial dura in order to expand the volume of the posterior cranial fossa. The reconstruction of occipital pool There are high complications associated with extensive decompression of the posterior cranial fossa, and the focus should be on relieving the compression of the cerebellar tonsils on the medulla oblongata and the adhesions formed between them, emphasizing the importance of cerebellar tonsillectomy to improve the outcome. 1.Cerebellar tonsillectomy After opening the skull and cutting the dura mater, the arachnoid membrane was further cut, and the cerebellar tonsils herniated into the occipital foramen were removed with bloodless aspiration under the soft membrane, so that the contents of the cerebellar tonsils were retracted and the compression on the medulla oblongata was released. 2.Unblocking the output tract of the fourth ventricle The previous steps of this method are the same as that of cerebellar tonsillectomy, and the adhesions between the herniated cerebellar tonsils and the brainstem are further separated microscopically and excised, the opening of the central canal of the spinal cord is explored, the thickened arachnoid membrane is loosened, and the cerebrospinal fluid circulation in the fourth ventricle is unblocked. This procedure has solved the pathogenesis of the spinal cord cavity and the obstruction of cerebrospinal fluid circulation at the foramen magnum, restoring the physiological state of cerebrospinal fluid circulation and improving cerebrospinal fluid dynamics. It should be a mandatory step in the surgical treatment of Chiari malformation with spinal cavity.