Khalsa Siri Sahib S, Geh Ndi, Martin Bryn A, Allen Philip A, Strahle Jennifer, Loth Francis, Habtzghi Desale, Urbizu Serrano Aintzane, McQuaide Daniel, Garton Hugh J L, Muraszko Karin M, Maher Cormac O
1Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan.
2Conquer Chiari Research Center, University of Akron, Ohio.
J Neurosurg Pediatr. 2018 Jan;21(1):65-71. doi: 10.3171/2017.8.PEDS17345. Epub 2017 Nov 10.
OBJECTIVE Chiari malformation Type I (CM-I) is typically defined on imaging by a cerebellar tonsil position ≥ 5 mm below the foramen magnum. Low cerebellar tonsil position is a frequent incidental finding on brain or cervical spine imaging, even in asymptomatic individuals. Nonspecific symptoms (e.g., headache and neck pain) are common in those with low tonsil position as well as in those with normal tonsil position, leading to uncertainty regarding appropriate management for many patients with low tonsil position and nonspecific symptoms. Because cerebellar tonsil position is not strictly correlated with the presence of typical CM-I symptoms, the authors sought to determine if other 2D morphometric or 3D volumetric measurements on MRI could distinguish between patients with asymptomatic and symptomatic CM-I. METHODS The authors retrospectively analyzed records of 102 pediatric patients whose records were in the University of Michigan clinical CM-I database. All patients in this database had cerebellar tonsil position ≥ 5 mm below the foramen magnum. Fifty-one symptomatic and 51 asymptomatic patients were matched for age at diagnosis, sex, tonsil position, and tonsil morphology. National Institutes of Health ImageJ software was used to obtain six 2D anatomical MRI measurements, and a semiautomated segmentation tool was used to obtain four 3D volumetric measurements of the posterior fossa and CSF subvolumes on MRI. RESULTS No significant differences were observed between patients with symptomatic and asymptomatic CM-I related to tentorium length (50.3 vs 51.0 mm; p = 0.537), supraoccipital length (39.4 vs 42.6 mm; p = 0.055), clivus-tentorium distance (52.0 vs 52.1 mm; p = 0.964), clivus-torcula distance (81.5 vs 83.3 mm; p = 0.257), total posterior fossa volume (PFV; 183.4 vs 190.6 ml; p = 0.250), caudal PFV (152.5 vs 159.8 ml; p = 0.256), fourth ventricle volume to caudal PFV ratio (0.0140 vs 0.0136; p = 0.649), or CSF volume to caudal PFV ratio (0.071 vs 0.061; p = 0.138). CONCLUSIONS No clinically useful 2D or 3D measurements were identified that could reliably distinguish pediatric patients with symptoms attributable to CM-I from those with asymptomatic CM-I.
目的 Ⅰ型Chiari畸形（CM-Ⅰ）在影像学上通常定义为小脑扁桃体位置低于枕大孔5mm及以下。小脑扁桃体位置偏低是脑部或颈椎影像学检查中常见的偶然发现，即使在无症状个体中也是如此。非特异性症状（如头痛和颈部疼痛）在小脑扁桃体位置偏低的患者以及小脑扁桃体位置正常的患者中都很常见，这使得许多有小脑扁桃体位置偏低和非特异性症状的患者在合适的治疗管理方面存在不确定性。由于小脑扁桃体位置与典型CM-Ⅰ症状的存在并不严格相关，作者试图确定MRI上的其他二维形态学或三维容积测量是否能够区分无症状和有症状的CM-Ⅰ患者。方法 作者回顾性分析了密歇根大学临床CM-Ⅰ数据库中102例儿科患者的记录。该数据库中的所有患者小脑扁桃体位置均低于枕大孔5mm及以下。51例有症状患者和51例无症状患者在诊断时的年龄、性别、扁桃体位置和扁桃体形态方面进行了匹配。使用美国国立卫生研究院ImageJ软件获取六个二维解剖MRI测量值，并使用半自动分割工具获取MRI上后颅窝和脑脊液子容积的四个三维容积测量值。结果 在有症状和无症状的CM-Ⅰ患者之间，与小脑幕长度（50.3对51.0mm；p = 0.537）、枕骨上部长度（39.4对42.6mm；p = 0.055）、斜坡-小脑幕距离（52.0对52.1mm；p = 0.964）、斜坡-窦汇距离（81.5对83.3mm；p = 0.257）、后颅窝总体积（PFV；183.4对190.6ml；p = 0.250）、尾侧PFV（152.5对159.8ml；p = 0.256）、第四脑室体积与尾侧PFV之比（0.0140对0.0136；p = 0.649）或脑脊液体积与尾侧PFV之比（0.071对0.061；p = 0.138）相关的指标均未观察到显著差异。结论 未发现可可靠区分有CM-Ⅰ所致症状的儿科患者和无症状CM-Ⅰ患者的具有临床实用价值的二维或三维测量方法。
