Department of Neurosurgery, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
J Neurosurg Spine. 2011 Dec;15(6):678-85. doi: 10.3171/2011.7.SPINE1152. Epub 2011 Aug 19.
Patient age at presentation with congenital atlantoaxial dislocation (CAAD) is variable. In addition, the factors determining irreducibility or reducibility in these patients remain unclear. The facets appear to contribute to the stability of the joint, albeit to an unknown extent. The objective of this paper was to study the characteristics of C1-2 facets in these patients and their bearing on the clinicoradiological presentation and management.
Twenty-four patients with CAAD were studied. Fifteen patients had irreducible CAAD (IrAAD); 3 of these patients experienced incomplete reduction after traction, and 9 had reducible CAAD (RAAD). The images (CT scans of the craniovertebral junction in a neutral position) obtained in the parasagittal, axial, and coronal planes were studied with respect to the C1-2 facets and were compared with 32 control scans. The inferior sagittal and coronal C-1 facet angles were measured. The lordosis of the cervical spine (cervical spine angle calculated on radiographs of the cervical spine, neutral view) in these patients was compared with normal. The management of these patients is described.
The inferior sagittal C-1 facet angle and at least one coronal angle in patients with IrAAD were significantly acute compared with those in patients with RAAD and the control population. A significant correlation was found between age and the acuteness of the inferior sagittal C-1 facet angle (that is, the more acute the angle, the earlier the presentation). The lordosis of the cervical spine was exaggerated in patients with IrAAD. Three patients with IrAAD who had smaller acute angles experienced a partial reduction after traction and a complete reduction after intraoperative distraction of the facets, thereby avoiding a transoral procedure. An inferior sagittal C-1 facet angle of more than 150° in the sagittal plane predicted reducibility. Drilling a wedge off the facet in the sagittal plane to make the inferior sagittal C-1 facet angle 150° can reduce the C1-2 joint intraoperatively by posterior approach alone.
The acuteness of the inferior C-1 sagittal facet angles possibly determines the age at presentation and reducibility. The coronal angles determine the telescoping of C-2 within C-1. Patients with IrAAD can be treated using a posterior approach alone with the exception of those with extremely acute angles or a retroflexed dens. The exaggerated lordosis of the cervical spine in these patients is a compensatory phenomenon.
患有先天性寰枢椎脱位（CAAD）的患者就诊时的年龄各不相同。此外，导致这些患者不可复位或可复位的因素仍不清楚。关节突似乎对关节的稳定性有一定的贡献，尽管其贡献程度尚不清楚。本文的目的是研究这些患者 C1-2 关节突的特征及其与临床影像学表现和治疗的关系。
研究了 24 例 CAAD 患者。15 例患者为不可复位 CAAD（IrAAD）；其中 3 例经牵引后不完全复位，9 例为可复位 CAAD（RAAD）。研究了矢状位、轴位和冠状位 CT 扫描中 C1-2 关节突的图像，并与 32 例对照扫描进行了比较。测量了下位颈椎矢状面和冠状面 C1 关节突角。与正常颈椎相比，测量了这些患者颈椎的颈椎前凸（颈椎中立位 X 线片上计算的颈椎前凸角）。描述了这些患者的治疗方法。
IrAAD 患者的下位颈椎矢状面 C1 关节突角和至少一个冠状面角明显较锐，与 RAAD 患者和对照组相比差异有统计学意义。年龄与下位颈椎矢状面 C1 关节突角的尖锐程度呈显著正相关（即角度越尖锐，发病年龄越早）。IrAAD 患者的颈椎前凸度增加。3 例 IrAAD 患者由于关节突角较小，经牵引后部分复位，术中关节突撑开后完全复位，避免了经口入路。矢状面中下颈椎矢状面 C1 关节突角大于 150°可预测可复位性。在矢状面钻除关节突的楔形以减小中下颈椎矢状面 C1 关节突角至 150°，可单独通过后路减少 C1-2 关节。
下位颈椎矢状面 C1 关节突角的尖锐程度可能决定了发病年龄和可复位性。冠状面角度决定了 C2 在 C1 内的套叠。除了关节突角非常尖锐或枢椎后倾的患者外，IrAAD 患者可单独采用后路治疗。这些患者的颈椎前凸度增加是一种代偿现象。
