Morphological Study On The Bone Structure Of Posterior Cranial Fossa In Adults With Simple Chiari Malformation Type Ⅰ

ObjectiveTo examine the characteristic of the bone structure in the posterior cranial fossa in adult simple Chiari malformation type Ⅰ(CMⅠ)patients associated without basilar invagination.MethodsAdult patients with simple CMⅠ admitted to the neurosurgical department of the First Affiliated Hospital of Chongqing Medical University from January 2018 to June 2020 were enrolled as the observation group,and sex-and age-matched healthy adults were selected as the control group.The differences in the linear and angular variables in the posterior cranial fossa between the two groups were analyzed based on the thin-slice CT data.ResultsThirty-eight patients were enrolled in each group,respectively.The clivus length(P < 0.001),supra-occipital length(P < 0.01),occipital length(P < 0.01),Klaus height index(P < 0.001),posterior compressive value(P< 0.01),tentorial angle(P < 0.05)and sagittal area of bony posterior cranial fossa(P < 0.001)in the observation group were significantly decreased,compared to the control group.The odontoid compressive value(P < 0.01),odontoid and soft tissue compressive value(P <0.01),anterior compressive value(P <0.01)and basal angle(P <0.01)of the observation group were significantly increased,compared with the control group.ConclusionThe clivus and occipital bone was shortened and elevated in adult simple CMⅠ patients,accompanied with ventral cervicomedullary compression due to posterior margin of odontoid process.