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The internal carotid artery and the atlas: anatomical relationship and implications for C1 lateral mass fixation
Angelo Rusconi1, Stefano Peron2, Paolo Roccucci2
1Neurosurgery Department, ASST West Milan Legnano Hospital, Milan, Italy. angelo.rusconi@hotmail.com.
Insights
Posterior C1 fixation risks injury to the internal carotid artery (ICA). This CT analysis quantizes ICA-C1 distances, providing crucial data for surgeons to minimize vascular complications during cervical spine surgery.
Area of Science:
- Neurosurgery
- Anatomy
- Radiology
Background:
- Posterior C1 fixation is a common surgical procedure.
- The internal carotid artery (ICA) is anatomically close to the C1 lateral mass.
- Iatrogenic injury to the ICA during C1 surgery is a rare but serious complication.
Purpose of the Study:
- To conduct a CT-based anatomical analysis of the relationship between the internal carotid artery (ICA) and the lateral mass of the atlas (C1).
- To provide quantitative data on the spatial relationship between the ICA and C1 to inform surgical planning for posterior C1 fixation.
Main Methods:
- Analysis of 30 cervical spine CT angiographies.
- Measurement of ICA distance from midline, C1 anterior cortex, and ideal C1 screw entry point.
- Calculation of the angle between the C1 screw trajectory and the ICA.
Main Results:
- Sixty internal carotid arteries (ICAs) were analyzed.
- Mean ICA distance from midline: 23.3 mm (min 15 mm).
- Mean distance from C1 anterior cortex: 4.8 mm (min 1.1 mm).
- Mean distance from ideal C1 screw entry point: 22.6 mm (min 17.5 mm).
- Mean angle between screw trajectory and ICA: 10.4° (min 11°).
Conclusions:
- Intraoperative injury to the internal carotid artery (ICA), though rare, poses a significant risk during posterior C1 fixation.
- Preoperative assessment of ICA position relative to C1 is mandatory.
- The anatomical parameters detailed in this study can aid surgeons in reducing the risk of ICA injury.
Purpose:
The internal carotid artery (ICA) is potentially at risk during posterior fixation of C1. In this study, we performed a CT-based anatomical analysis of the relationship between the internal carotid artery and the lateral mass of the atlas.
Methods:
We analysed 30 CT angiography of the cervical spine, and we measured on both sides the distance of the carotid artery from the midline, distance of the ICA from the anterior cortex of C1 and from the ideal C1 screw entry point. We measured the angle between the sagittal plane passing through the entry point and the tangent line of the vessel. Separated statistical analysis between left and right sides, between male and female patients, and differentiation by age were also performed.
Results:
Sixty ICAs were studied. The mean distance of the ICA from the midline was 23.3 ± 4.3 mm, with a minimum of 15 mm. The distance between the ICA and the anterior cortical layer of C1 was 4.8 ± 2.7 mm, with a minimum of 1.1 mm. The distance between the screw entry point and the arterial wall was 22.6 ± 2.8 mm, with a minimum of 17.5 mm. The mean angle was 10.4°, with a minimum of 11°.
Conclusions:
Although rare, intraoperative lesion of the ICA is reported and the spine surgeon must be aware of this risk. Careful preoperative planning is mandatory and the position of the ICA in relation to C1 must be assessed. The anatomical parameters presented in this paper can be useful to reduce the risk of ICA injury.
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