Perera Ishan R, Zahed Malek, Moriarty Sydney, Simmons Zachary, Rodriguez Maya, Botkin Courtney, Dickson Taylor, Kasper Bradley, Fahmy Kendyl, Millard Jonathan A
Edward Via College of Osteopathic Medicine, Blacksburg, VA, United States.
Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA, United States.
Front Neuroanat. 2024 Aug 7;18:1434017. doi: 10.3389/fnana.2024.1434017. eCollection 2024.
Chiari I malformation (CMI) is characterized by inferior descent of the cerebellar tonsils through the foramen magnum and is associated with headache and neck pain. Many morphometric research efforts have aimed to describe CMI anatomy in the midsagittal plane using classical measurement techniques such as linear dimensions and angles. These methods are less frequently applied to parasagittal features and may fall short in quantifying more intricate anatomy with fewer distinct homologous landmarks.
Landmark-based geometric morphometric techniques were used to asses CMI morphology in five anatomical planes of interest.
Significant shape differences between CMI and age/sex-matched controls were found in the midsagittal (Pseudo- = 5.4841, = 0.001) and axial planes through the rostral medulla (Pseudo- = 7.6319, = 0.001). In addition to tonsillar descent, CMI principal component 1 (PC1) scores in the midsagittal protocol were associated with marked anterior concavity of the brainstem and generalized verticality of the cerebellum with anterior rotation of its anterior lobe. In the axial medulla/cerebellum protocol, CMI PC1 scores were associated with greater anterior-posterior (A-P) dimension with loss of medial-lateral (M-L) dimension.
These results suggest that CMI is associated with greater curvature of the brainstem and spinal cord, which may perturb normal neural activities and disrupt cerebrospinal fluid movements. Previous reports on the A-P diameter of the posterior fossa in CMI have conflicted; our findings of greater A-P cerebellar dimensionality with concomitant loss of width alludes to the possibility that more caudal aspects of the posterior cranial fossa are more bowl-like (homogenous in axial dimensions) and less trough-like or elongated in the M-L direction.
Chiari I 畸形（CMI）的特征是小脑扁桃体通过枕骨大孔向下移位，并伴有头痛和颈部疼痛。许多形态学研究致力于使用线性尺寸和角度等经典测量技术在正中矢状面描述CMI的解剖结构。这些方法较少应用于旁矢状面特征，并且在量化具有较少明显同源标志的更复杂解剖结构时可能存在不足。
基于地标点的几何形态测量技术用于评估五个感兴趣解剖平面中的CMI形态。
在正中矢状面（伪F = 5.4841，P = 0.001）和通过延髓头端的轴位平面（伪F = 7.6319，P = 0.001）中发现CMI与年龄/性别匹配的对照组之间存在显著的形状差异。除了扁桃体下移外，正中矢状面方案中CMI的主成分1（PC1）得分与脑干明显的前凹以及小脑的整体垂直性及其前叶的前旋有关。在轴位延髓/小脑方案中，CMI的PC1得分与更大的前后径（A-P）相关，同时内外径（M-L）减小。
这些结果表明CMI与脑干和脊髓的更大曲率相关，这可能扰乱正常的神经活动并破坏脑脊液流动。先前关于CMI后颅窝前后径的报道存在矛盾；我们发现小脑前后径增大同时宽度减小，这暗示后颅窝更靠尾侧的部分更呈碗状（轴向尺寸均匀），而在内外方向上较少呈槽状或拉长。
