In Chiari malformation type I (CM-I), a variety of imaging findings have been purported to be important; however, results have been inconclusive, inconsistent, or not replicated in independent studies. The purpose of this study was to report imaging characteristics for a large cohort of patients with CM-I and identify the imaging findings associated with surgical decompression.

Patients were identified using ICD-9 codes for CM-I for the period from 1996 to 2017. After review of the medical records, patients were excluded if they 1) did not have a diagnosis of CM-I, 2) were not evaluated by a neurosurgeon, or 3) did not have available preoperative MRI. Retrospective chart review was performed to collect demographic and clinical data. Imaging parameters were measured according to the Chiari I Malformation Common Data Elements.

A total of 731 patients were included for analysis, having a mean follow-up duration of 25.5 months. The mean age at presentation was 8.5 years. The mean tonsil position was 11.4 mm below the foramen magnum, and 62.8% of patients had a pegged tonsil shape. Two hundred patients (27.4%) underwent surgery for life-dominating tussive headache, lower cranial nerve dysfunction, syrinx, and/or brainstem dysfunction. Surgical treatment was associated with a syrinx (OR 20.4, 95% CI 12.3–33.3, p < 0.0001), CM-1.5 (OR 1.797, 95% CI 1.08–2.98, p = 0.023), lower tonsil position (OR 1.130, 95% CI 1.08–1.18, p < 0.0001), and congenital fusion of cervical vertebrae (OR 5.473, 95% CI 1.08–27.8, p = 0.040). Among patients with benign CM-I, tonsil position was statistically significantly associated with future surgery.

Comprehensive imaging characteristics for a large cohort of patients with CM-I are reported. Analysis showed that a lower tonsillar position, a syrinx, and CM-1.5 were associated with undergoing posterior fossa decompression. This study demonstrates the importance of considering imaging findings in the context of patient symptomatology.

在 Chiari I 型畸形 (CM-I) 中，各种影像学表现被认为是重要的；然而，结果在独立研究中没有定论、不一致或没有重复。本研究的目的是报告一大群 CM-I 患者的影像学特征，并确定与手术减压相关的影像学表现。

使用 1996 年至 2017 年期间 CM-I 的 ICD-9 代码识别患者。在审查医疗记录后，如果患者 1) 未诊断为 CM-I，2) 未通过以下方式评估，则将其排除在外神经外科医生，或 3) 没有可用的术前 MRI。进行回顾性图表审查以收集人口统计学和临床​​数据。根据 Chiari I Malformation Common Data Elements 测量成像参数。

共有 731 名患者被纳入分析，平均随访时间为 25.5 个月。就诊时的平均年龄为 8.5 岁。扁桃体平均位置在枕骨大孔下方 11.4 毫米，62.8% 的患者呈钉状扁桃体形状。200 名患者 (27.4%) 因以生命为主的咳嗽性头痛、下颅神经功能障碍、空洞和/或脑干功能障碍而接受了手术。手术治疗与空洞相关（OR 20.4，95% CI 12.3-33.3，p < 0.0001），CM-1.5（OR 1.797，95% CI 1.08-2.98，p = 0.023），较低的扁桃体位置（OR 113，P < 0.0001） % CI 1.08–1.18，p < 0.0001）和先天性颈椎融合（OR 5.473，95% CI 1.08–27.8，p = 0.040）。在良性 CM-I 患者中，扁桃体位置与未来手术有统计学显着相关性。

报告了大量 CM-I 患者的综合成像特征。分析表明，较低的扁桃体位置、空洞和 CM-1.5 与接受后颅窝减压有关。这项研究证明了在患者症状的背景下考虑影像学检查结果的重要性。