摘要
Measuring the sagittal canal diameter(SCD)is crucial for cervical spine assessment.A small SCD predisposes patients to myelopathy.[1]Stenosis is less common at the C1 level than at the levels below C2.[2,3]The existing literature regarding hypoplastic stenosis at the C1 level includes a few case reports;based on the literature,C1 hypoplasia seems to be more common in Chinese populations.[3,4]Normative values of C1 SCD may help in the evaluation of potential cervical stenosis in a given clinical situation;they were reported as adequately powered for defining pure C1 hypoplasia.[2,5]However,there is a paucity of data on C1 SCD in Chinese populations compared with those in other populations[Supplemental Table 1,http://links.lww.com/CM9/A538].Among several measurement methods,in vivo computed tomography(CT)-based measurements have been validated and found to be as accurate as measurements in cadaver studies.[1]Thus,we aimed to use CT-based measurements to establish normative values for C1 SCD in Chinese adults and to define C1 hypoplasia.