In brief, a midline incision was made from the inion to the C2 level. A piece of autologous fascia was harvested from the muscular fascia layer. Paraspinal muscles were dissected to expose the occipital bone, posterior arch of the atlas and axis, spinous process, and lamina. The inferior portion of the occipital bone and approximately 2 cm of the posterior arch of C1 were removed, achieving bony decompression (approximately 2.5-3 × 2.5-3 cm). Once the dura was exposed, the atlanto-occipital membrane was coagulated and dissected off the dura. The dura was then incised in a Y-shaped fashion, with care taken to preserve the underlying arachnoid. Watertight duraplasty was performed using the autologous fascia. The wound was closed in anatomical layers.

Briefly, a midline incision approximately 3-4 cm posterior to the foramen magnum is made. The incision is deepened layer by layer along the midline to reach the occipital bone, exposing the posterior margin of the foramen magnum and part of the occipital squama. The posterior edge of the foramen magnum is opened, and part of the occipital squama is removed up to the junction of the cerebellar vermis and cerebellar tonsils. The occipitoatlantal fascia is exposed and dissected. The dura mater and arachnoid mater are incised longitudinally and suspended bilaterally to provide a clear surgical field. The primary objectives of resection were: ensuring no significant obstruction of CSF circulation at the foramen magnum and the foramen of Magendie under natural conditions. Preventing occlusion of the foramen of Magendie caused by herniated cerebellar tonsils or any membranous structures under natural conditions. The dura is closed in situ.

In brief, a midline incision was made from the inion to the C2 level. A piece of autologous fascia was harvested from the muscular fascia layer. Paraspinal muscles were dissected to expose the occipital bone, posterior arch of the atlas and axis, spinous process, and lamina. The inferior portion of the occipital bone and approximately 2 cm of the posterior arch of C1 were removed, achieving bony decompression (approximately 2.5-3 × 2.5-3 cm). Once the dura was exposed, the atlanto-occipital membrane was coagulated and dissected off the dura. The dura was then incised in a Y-shaped fashion, with care taken to preserve the underlying arachnoid. Watertight duraplasty was performed using the autologous fascia. The wound was closed in anatomical layers.

defined as > 50% improvement in length, maximal cross-sectional diameter, or both.

Reoperation,Wound infection,Aseptic meningitis,CSF fistula,Subcutaneous hydrops,Other complications

for evaluating the spinal cord function after chiari decompression surgery, Each item is scored on a scale from 1 to 4, with 4 representing the best possible functional status.