Haller Gabe, Sadler Brooke, Kuensting Timothy, Lakshman Nivan, Greenberg Jacob K, Strahle Jennifer M, Park Tae Sung, Dobbs Matthew B, Gurnett Christina A, Limbrick David D
Departments of1Neurological Surgery.
2Neurology.
J Neurosurg Pediatr. 2020 Apr 10;26(1):45-52. doi: 10.3171/2020.2.PEDS19486. Print 2020 Jul 1.
Chiari I malformation (CM-I) has traditionally been defined by measuring the position of the cerebellar tonsils relative to the foramen magnum. The relationships of tonsillar position to clinical presentation, syringomyelia, scoliosis, and the use of posterior fossa decompression (PFD) surgery have been studied extensively and yielded inconsistent results. Obex position has been proposed as a useful adjunctive descriptor for CM-I and may be associated with clinical disease severity.
A retrospective chart review was performed of 442 CM-I patients with MRI who presented for clinical evaluation between 2003 and 2018. Clinical and radiological variables were measured for all patients, including presence/location of headaches, Chiari Severity Index (CSI) grade, tonsil position, obex position, clival canal angle, pB-C2 distance, occipitalization of the atlas, basilar invagination, syringomyelia, syrinx diameter, scoliosis, and use of PFD. Radiological measurements were then used to predict clinical characteristics using regression and survival analyses, with performing PFD, the presence of a syrinx, and scoliosis as outcome variables.
Among the radiological measurements, tonsil position, obex position, and syringomyelia were each independently associated with use of PFD. Together, obex position, tonsil position, and syringomyelia (area under the curve [AUC] 89%) or obex position and tonsil position (AUC 85.4%) were more strongly associated with use of PFD than tonsil position alone (AUC 76%) (Pdiff = 3.4 × 10-6 and 6 × 10-4, respectively) but were only slightly more associated than obex position alone (AUC 82%) (Pdiff = 0.01 and 0.18, respectively). Additionally, obex position was significantly associated with occipital headaches, CSI grade, syringomyelia, and scoliosis, independent of tonsil position. Tonsil position was associated with each of these traits when analyzed alone but did not remain significantly associated with use of PFD when included in multivariate analyses with obex position.
Compared with tonsil position alone, obex position is more strongly associated with symptomatic CM-I, as measured by presence of a syrinx, scoliosis, or use of PFD surgery. These results support the role of obex position as a useful radiological measurement to inform the evaluation and potentially the management of CM-I.
传统上，Chiari I型畸形（CM-I）是通过测量小脑扁桃体相对于枕骨大孔的位置来定义的。扁桃体位置与临床表现、脊髓空洞症、脊柱侧弯以及后颅窝减压（PFD）手术的使用之间的关系已得到广泛研究，但结果并不一致。有人提出闩位置可作为CM-I的一个有用的辅助描述指标，并且可能与临床疾病严重程度相关。
对2003年至2018年间因临床评估而接受MRI检查的442例CM-I患者进行回顾性病历审查。测量了所有患者的临床和放射学变量，包括头痛的存在/位置、Chiari严重程度指数（CSI）分级、扁桃体位置、闩位置、斜坡管角度、pB-C2距离、寰椎枕化、基底凹陷、脊髓空洞症、空洞直径、脊柱侧弯以及PFD的使用情况。然后使用放射学测量结果，通过回归分析和生存分析来预测临床特征，将是否进行PFD、是否存在空洞以及脊柱侧弯作为结果变量。
在放射学测量中，扁桃体位置、闩位置和脊髓空洞症各自均与PFD的使用独立相关。相比单独的扁桃体位置（曲线下面积[AUC] 76%），闩位置、扁桃体位置和脊髓空洞症共同（AUC 89%）或闩位置和扁桃体位置共同（AUC 85.4%）与PFD的使用关联更强（P差异分别为3.4×10-6和6×10-4），但仅比单独的闩位置（AUC 82%）稍强（P差异分别为0.01和0.18）。此外，独立于扁桃体位置，闩位置与枕部头痛、CSI分级、脊髓空洞症和脊柱侧弯显著相关。单独分析时，扁桃体位置与这些特征均相关，但在与闩位置进行多变量分析时，与PFD的使用不再显著相关。
与单独的扁桃体位置相比，通过是否存在空洞、脊柱侧弯或使用PFD手术来衡量，闩位置与有症状的CM-I关联更强。这些结果支持闩位置作为一种有用的放射学测量指标在CM-I评估及可能的管理中的作用。
