Departments of1Neurosurgery and.
2Institute of Clinical Medicine, Faculty of Medicine, University of Oslo; and.
J Neurosurg Pediatr. 2024 Jul 5;34(3):293-300. doi: 10.3171/2024.4.PEDS24168. Print 2024 Sep 1.
Reduced intracranial compliance (ICC) may be an important factor in the pathophysiology of Chiari malformation type I (CM-I). However, direct measurement of ICC is controversial because of its invasiveness, particularly in children. Instead, ICC may be estimated from continuous measurements of intracranial pressure (ICP), where the metric mean wave amplitude (MWA) has been found to be more useful as a surrogate marker of ICC than mean ICP. This observational study investigated the distribution of MWA and mean ICP in symptomatic children with CM-I, as well as their association with clinical and radiological findings.
From a consecutive series of children treated for CM-I at a single institution between 2006 and 2023, the authors analyzed ICP scores in those who underwent an overnight preoperative ICP recording in which MWA was calculated. Clinical and radiological data were retrieved from the patient records.
Thirty-seven children (mean age 12.4 ± 3.6 years) with symptomatic CM-I were identified. From the overnight ICP measurements, the average MWA was 5.2 ± 1.3 mm Hg: 56% of children had an abnormal MWA (> 5 mm Hg) and 33% had a borderline MWA (4-5 mm Hg). In contrast, the average mean ICP was 9.7 ± 4.1 mm Hg: 8% of children had an abnormal mean ICP (> 15 mm Hg) and 41% had a borderline mean ICP (10-15 mm Hg). Thus, more children were found to have an abnormal MWA than an abnormal mean ICP (p < 0.001). MWA was significantly higher in the subgroup of children with medullary compression in the foramen magnum, as seen on MRI, than in those without (5.6 ± 1.0 mm Hg vs 4.7 ± 1.4 mm Hg, p = 0.03), whereas a similar difference was not observed for mean ICP (9.9 ± 4.6 mm Hg vs 9.7 ± 3.7 mm Hg, p = 0.889).
In this cohort of symptomatic children with CM-I, MWA was more frequently abnormal than mean ICP, with a clinically significant discrepancy in half of the patients. Moreover, MWA was significantly higher in patients with medullary compression. Based on these findings, the authors' interpretation is that in children with CM-I, the ICC may be reduced, as indicated by increased MWA, even though the mean ICP is within normal thresholds.
颅内顺应性（intracranial compliance，ICC）降低可能是 Chiari 畸形 I 型（Chiari malformation type I，CM-I）病理生理学的一个重要因素。然而，由于其侵袭性，特别是在儿童中，直接测量 ICC 存在争议。相反，ICC 可以通过连续测量颅内压（intracranial pressure，ICP）来估计，其中已经发现，与平均 ICP 相比，平均波幅（mean wave amplitude，MWA）作为 ICC 的替代标志物更有用。本观察性研究调查了伴有 CM-I 的症状性儿童的 MWA 和平均 ICP 的分布情况，以及它们与临床和影像学发现的关系。
作者分析了 2006 年至 2023 年间在一家机构接受治疗的 CM-I 连续病例系列中，那些接受过夜术前 ICP 记录的患者的 ICP 评分，其中计算了 MWA。从患者记录中检索临床和影像学数据。
作者确定了 37 例伴有症状性 CM-I 的儿童（平均年龄 12.4 ± 3.6 岁）。从过夜 ICP 测量中，平均 MWA 为 5.2 ± 1.3mmHg：56%的儿童 MWA 异常（>5mmHg），33%的儿童 MWA 边界异常（4-5mmHg）。相比之下，平均平均 ICP 为 9.7 ± 4.1mmHg：8%的儿童平均 ICP 异常（>15mmHg），41%的儿童平均 ICP 边界异常（10-15mmHg）。因此，与异常平均 ICP 相比，更多的儿童被发现 MWA 异常（p<0.001）。与无 MRI 矢状窦下孔髓压迫的儿童相比，有 MRI 矢状窦下孔髓压迫的儿童 MWA 明显更高（5.6 ± 1.0mmHg 比 4.7 ± 1.4mmHg，p=0.03），而平均 ICP 则没有类似的差异（9.9 ± 4.6mmHg 比 9.7 ± 3.7mmHg，p=0.889）。
在本队列中，伴有 CM-I 的症状性儿童中，MWA 比平均 ICP 更常异常，半数患者存在显著的临床差异。此外，在有髓压迫的患者中，MWA 明显更高。基于这些发现，作者的解释是，在伴有 CM-I 的儿童中，ICC 可能降低，表现为 MWA 升高，尽管平均 ICP 处于正常范围内。
