Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China.
Department of Neurosurgery, King Edward VII Memorial Hospital and Seth G.S. Medical College, Parel, Mumbai, Maharashtra, India.
Clin Spine Surg. 2020 Oct;33(8):E386-E390. doi: 10.1097/BSD.0000000000000971.
A mechanism-based reasoning and case-control study.
To introduce correction target of clivo-axial angle (CXA) in quantitative surgical reduction of basilar invagination (BI).
The exact mechanism of BI with or without atlantoaxial dislocation is still unclear. Sagittal deformity is a key feature of BI. Correction of CXA directly influences subaxial cervical lordosis (increase of CXA equals the decrease of cervical lordosis). However, a quantitative reference for correction surgery has not been established.
CXA was divided by Chamberlain line into clivus tilt (CT) and axial tilt (AT). Patients diagnosed with BI were retrospectively included. Patients with degenerative cervical spine diseases or vascular diseases (without BI) were included as controls. CT, AT, and other common parameters were measured and analyzed with t test and multiple linear regression. Demonstration case was presented.
A total of 42 BI patients and 23 controls were included. Normal references for CXA, AT, and CT were 162.3±7.1, 93.8±6.5, and 68.6±3.8 degrees, respectively. BI patients had a 30.3-degree smaller CXA, a 15.5-degree smaller AT, and a 14.9-degree smaller CT. Basal angle (P=0.002) independently had a significant influence on extent of BI, while CT and AT did not. Demonstration case showed that CT was fixed and correcting AT to an ideal 94 degrees was optimal for an individual patient.
Proper quantitative correction of CXA needs to be individualized in consideration of CT and AT. The difference between actual AT and its ideal value (about 94 degrees) is the optimal target of CXA correction to decompress neural elements ventrally and recover better subaxial cervical lordosis.
Level IV.
基于机制推理的病例对照研究。
介绍颅底凹陷症伴或不伴寰枢椎脱位患者定量手术复位时的枕髁-轴角（CXA）校正目标。
颅底凹陷症伴或不伴寰枢椎脱位的确切机制仍不清楚。矢状面畸形是颅底凹陷症的一个关键特征。CXA 的矫正直接影响下颈椎的前凸（CXA 的增加等于颈椎前凸的减少）。然而，尚未建立定量矫正手术的参考标准。
通过 Chamberlain 线将 CXA 分为斜坡倾斜角（CT）和轴倾斜角（AT）。回顾性纳入诊断为颅底凹陷症的患者。将患有退行性颈椎疾病或血管疾病（无颅底凹陷症）的患者纳入对照组。采用 t 检验和多元线性回归分析测量和分析 CT、AT 和其他常见参数。展示了一个病例。
共纳入 42 例颅底凹陷症患者和 23 例对照组。CXA、AT 和 CT 的正常参考值分别为 162.3±7.1、93.8±6.5 和 68.6±3.8 度。颅底凹陷症患者的 CXA 小 30.3 度，AT 小 15.5 度，CT 小 14.9 度。基底角（P=0.002）对颅底凹陷症的严重程度有独立的显著影响，而 CT 和 AT 没有。病例展示表明 CT 是固定的，将 AT 矫正到理想的 94 度对个体患者是最佳的。
在考虑 CT 和 AT 的情况下，需要个体化适当的 CXA 定量矫正。实际 AT 与其理想值（约 94 度）之间的差异是 CXA 矫正的最佳目标，以实现对神经结构的减压和更好的下颈椎前凸的恢复。
IV 级。
