RESUMEN
Objective To investigate the pathogenesis of the syringomyelia in Chiari I malformation by measuring the posterior cranial fossa structures. Methods The posterior cranial fossa structures on mid sagittal MR image were measured in 50 normal subjects,and 24 Chiari I malformation patients associated with syringomyelia and 26 Chiari I malformation patients without syringomyelia. The t test was used for statistical analysis. Results In Chiari I malformation patients and normal subjects, the width of the CSF space anterior to the medulla oblongata was (4 2?1 8) mm and (6 6?1 4) mm respectively( t =7 30, P 0 05). In Chiari I malformation with syringomyelia group and without syringomyelia group, the width of the CSF space anterior to the medulla oblongata was (2 9?1 4) mm and (5 5?1 1) mm respectively( t =7 30, P