St. Vincent's Hospital, Department of Neurosurgery, The Catholic University of Korea, Seoul, South Korea.
J Neurosurg Spine. 2010 Jun;12(6):613-8. doi: 10.3171/2010.1.SPINE09409.
The aim of this study was to analyze the exact location of the internal carotid artery (ICA) relative to the C-1 lateral mass and describe the effect of age on the tortuosity of the ICA.
The authors analyzed 641 patients who had undergone CT angiography to evaluate the location of the ICA in relation to the C-1 lateral mass. Each patient was assigned to 1 of 3 age groups (< 41 years, 41-60 years, and > 60 years of age). The degree of lateral positioning of the ICA was classified into 4 groups: Group 1 (lateral to the C-1 lateral mass), Group 2 (lateral half of the lateral mass), Group 3 (medial half of the lateral mass), or Group 4 (medial to the lateral mass). The anteroposterior relationship of the ICA was classified into Group A (posterior to the anterior tubercle) or Group B (anterior to the anterior tubercle). Distances from the ICA to the midline, anterior tubercle, and anterior cortex of the lateral mass were measured. Distances between the lateral margin of the lateral mass and the longus capitis muscle were also evaluated.
The prevalence of the ICA located in front of the lateral mass (Groups 2 and 3) was 47.4% overall. The position of the ICA changes with age due to vessel tortuosity. Only 18.3% of patients in the youngest age group (< 41 years of age) had an ICA in front of the lateral mass (Group 2 or 3 area). However, this percentage increased in the older 2 groups (43.5% in the 41-60 year old group, and 57% in the > 60-year-old age group). The mean distance from the midline to the ICA was 22.6 mm, and the mean distance from the ICA to the C-1 anterior tubercle and the ventral cortex of the lateral mass was 4.7 and 4.5 mm, respectively. Moreover, the ICA is more prone to injury during bicortical C-1 screw placement when the longus capitis muscle is hypotrophic and does not cover the entire ventral surface of the lateral mass.
Elderly patients have a higher incidence of a medially located ICA that may contribute to the risk of injury to the ICA during bicortical C-1 screw or C1-2 transarticular screw placement. Although the small number of reported cases of ICA injury does not allow for determination of a direct relationship with specific anatomical characteristics, the presence of unfavorable anatomy does warrant serious consideration during evaluation for C-1 screw placement in elderly patients.
本研究旨在分析颈内动脉（ICA）相对于 C1 侧块的确切位置，并描述年龄对 ICA 迂曲程度的影响。
作者分析了 641 例接受 CT 血管造影术评估 ICA 与 C1 侧块位置关系的患者。将每位患者分为 3 个年龄组（<41 岁、41-60 岁和>60 岁）之一。ICA 外侧定位程度分为 4 组：第 1 组（位于 C1 侧块外侧）、第 2 组（位于侧块外侧半）、第 3 组（位于侧块内侧半）或第 4 组（位于侧块内侧）。ICA 的前后关系分为 A 组（位于前结节后方）或 B 组（位于前结节前方）。测量 ICA 至中线、前结节和侧块前皮质的距离。还评估了侧块外侧缘与头长肌之间的距离。
ICA 位于侧块前方（第 2 组和第 3 组）的总体患病率为 47.4%。由于血管迂曲，ICA 的位置随年龄而变化。只有<41 岁年龄组（18.3%）的患者 ICA 位于侧块前方（第 2 或 3 区）。然而，在年龄较大的 2 个组中，这一比例增加（41-60 岁年龄组为 43.5%，>60 岁年龄组为 57%）。ICA 至中线的平均距离为 22.6mm，ICA 至 C1 前结节和侧块腹侧皮质的平均距离分别为 4.7mm 和 4.5mm。此外，当头长肌萎缩且未覆盖侧块腹侧表面时，ICA 在双皮质 C1 螺钉放置过程中更容易受伤。
老年患者 ICA 更易位于内侧，这可能增加在双皮质 C1 螺钉或 C1-2 经关节螺钉放置过程中损伤 ICA 的风险。尽管报告的 ICA 损伤病例数量较少，无法确定与特定解剖特征的直接关系，但在评估老年患者 C1 螺钉放置时，存在不利的解剖结构确实需要认真考虑。
