OBJECTIVE: To clarify the efficacy of two different procedures for the treatment of Chiari malformation combined with spinal cord cavity by retrospectively comparing the treatment of Chiari malformation combined with spinal cord cavity with decompression duralplasty in the occipital foramen magnum and decompression loop occipital fasciotomy in the occipital foramen magnum. METHODS: From January 2002 to April 2004, 62 patients, 27 males and 35 females, aged 12-69 years, with a mean of 39.7±12.2 years (`X±s years), were admitted to our department with ChiariI malformation combined with spinal cavity, and the duration of disease was 1 month-30 years, with a mean of 5.6 years. The dura was cut in 46 patients and duroplasty was performed with alternative materials (duroplasty group), and the dura was not cut in the remaining 16 patients (fascial release group), except for cricoaxial subluxation in all patients. All patients underwent MR examination, and the diagnostic criteria were that the cerebellar tonsils were more than 5 mm below the greater occipital foramen, the greater occipital pool was absent in all cases, the lower herniation did not exceed the lower edge of C2, and there was no cervical subluxation. The occipital decompression was 5×4 cm in size, and whether to remove the posterior arch of the cervical spine to reveal the inferior border of the cerebellar tonsils was decided according to the degree of herniation under general anesthesia, and the dura was cut in Y-shape under microscope in the duralplasty group. In 46 patients, the dura mater was cut under the microscope and the Neuropatch (B. Braun Melsungen AG) or autologous broad thigh fascia was trimmed into a triangular shape to repair the dura mater (dura mater group), while in the remaining 16 patients, the dura mater was not cut (fascial release group) and the crico-occipital fascia was fully released and the outer layer of the dura mater was cut under the microscope. The posterior margin of the foramen magnum was found to be invaginated and thickened to varying degrees, the atlanto-occipital membrane was hypertrophied, cord-like, partially calcified, and the posterior atlanto-axial arch was underdeveloped in some patients, and the dura mater and the herniated cerebellar tonsils were adherent to the arachnoid membrane. The postoperative outcome evaluation index: postoperative neurological function evaluation, based on Tator score [3], is excellent if the symptoms and signs improve significantly after surgery, good if the symptoms and signs are stable, and poor if the neurological function deteriorates after surgery. Postoperative MR review of spinal cavity reduction was performed. The improvement rate was the number of improved patients/total number of patients, and the t-test was applied to the measurement data and the χ2 test to the count data, and the data were analyzed by the statistical package SPSS10.0. Results: There were no significant differences between the two groups in terms of gender, age, disease duration and clinical manifestations, and the two groups were comparable. All patients were followed up 1 year after surgery. 39 patients (84.78%) in the duralplasty group and 9 patients (56.25%) in the membrane release group showed clinical improvement 1 year after surgery, χ2=5.528, P=0.019, and no aggravation was seen. The head and neck limb pain and numbness disappeared or were relieved in 35 cases (59.32%) in the duralplasty group. MR review showed that the cavity was reduced or disappeared in 30 cases (65.22%) in the duralplasty group and 7 cases (43.75%) in the fascial release group. Conclusion: Decompression duralplasty in the greater occipital foramen is a more reasonable procedure for the treatment of Chiari malformation combined with spinal cord cavitation, and its efficacy is better than that of decompression loop occipital fasciotomy in the greater occipital foramen.