Corcoran B, Linscott L L, Leach J L, Vadivelu S
From the Departments of Radiology (B.C., L.L.L., J.L.L.).
From the Departments of Radiology (B.C., L.L.L., J.L.L.)
AJNR Am J Neuroradiol. 2016 May;37(5):958-62. doi: 10.3174/ajnr.A4641. Epub 2016 Jan 7.
Prior studies have found that widening or asymmetry of the occipital condyle-C1 interval on CT is a sensitive and specific marker for atlanto-occipital dislocation. Previously reported abnormal occipital condyle-C1 interval values are not age-specific, possibly leading to false-positive findings in younger children, in whom this joint space is normally larger than that in adults. This study assesses the utility of applying age-specific normative occipital condyle-C1 interval ranges to documented cases of atlanto-occipital injury compared with previously reported abnormal cutoff values.
Retrospective review of CT and MR imaging of 14 subjects with atlanto-occipital injury was performed, and occipital condyle-C1 interval measurements were made for each subject. Sensitivities and specificities of proposed occipital condyle-C1 interval cutoffs of 2 and 3 SDs above the mean and previously published occipital condyle-C1 interval cutoffs for atlanto-occipital injury were then calculated on the basis of occipital condyle-C1 interval measurements for each subject.
An occipital condyle-C1 interval 2 SDs above the age-specific mean has a sensitivity of 50% and specificity of 89%-100%, depending on the age group. An occipital condyle-C1 interval 3 SDs above the age-specific mean has a sensitivity of 50% and a specificity of 95%-100%. A 4.0-mm occipital condyle-C1 interval has a sensitivity of 36% and a specificity of 100% in all age groups. A 2.5-mm occipital condyle-C1 interval has a sensitivity of 93% and a specificity of 18%-100%.
Occipital condyle-C1 interval widening cutoffs used to establish atlanto-occipital injury lack both sensitivity and specificity in children and young teenagers. MR imaging is necessary to establish a diagnosis of atlanto-occipital injury in children and young teenagers when the appropriate mechanism of injury is present.
既往研究发现，CT上枕髁-C1间隙增宽或不对称是寰枕关节脱位的敏感且特异的标志。先前报道的枕髁-C1间隙异常值未针对年龄进行区分，这可能导致年幼儿童出现假阳性结果，因为该关节间隙在年幼儿童中通常比成人更大。本研究评估与先前报道的异常临界值相比，应用针对年龄的枕髁-C1间隙正常范围对已记录的寰枕关节损伤病例的实用性。
对14例寰枕关节损伤患者的CT和MR成像进行回顾性分析，对每位患者进行枕髁-C1间隙测量。然后根据每位患者的枕髁-C1间隙测量值，计算高于均值2个标准差和3个标准差的拟枕髁-C1间隙临界值以及先前发表的寰枕关节损伤枕髁-C1间隙临界值的敏感度和特异度。
高于年龄特异性均值2个标准差的枕髁-C1间隙，其敏感度为50%，特异度为89%-100%，具体取决于年龄组。高于年龄特异性均值3个标准差的枕髁-C1间隙，其敏感度为50%，特异度为95%-100%。4.0mm的枕髁-C1间隙在所有年龄组中的敏感度为36%，特异度为100%。2.5mm的枕髁-C1间隙，其敏感度为93%，特异度为18%-100%。
用于诊断寰枕关节损伤的枕髁-C1间隙增宽临界值在儿童和青少年中缺乏敏感度和特异度。当存在合适的损伤机制时，儿童和青少年的寰枕关节损伤诊断需要MR成像。
