We investigated the incidence of anomalies in
the vertebral arteries and Circle of Willis with three-dimensional
CT angiography in 55 consecutive patients who had undergone an instrumented
posterior fusion of the cervical spine. We recorded any peri-operative and post-operative complications.
The frequency of congenital anomalies was 30.9%, abnormal vertebral
artery blood flow was 58.2% and vertebral artery dominance 40%. The posterior communicating artery was occluded on one side in
41.8% of patients and bilaterally in 38.2%. Variations in the vertebral
arteries and Circle of Willis were not significantly related to
the presence or absence of posterior communicating arteries. Importantly,
18.2% of patients showed characteristic variations in the Circle
of Willis with unilateral vertebral artery stenosis or a dominant
vertebral artery, indicating that injury may cause lethal complications.
One patient had post-operative cerebellar symptoms due to intra-operative
injury of the vertebral artery, and one underwent a different surgical
procedure because of insufficient collateral circulation. Pre-operative assessment of the vertebral arteries and Circle
of Willis is essential if a posterior spinal fusion with instrumentation
is to be carried out safely. Cite this article:
This study investigated the anatomical relationship between the clavicle and its adjacent vascular structures, in order to define safe zones, in terms of distance and direction, for drilling of the clavicle during osteosynthesis using a plate and screws following a fracture. We used reconstructed three-dimensional CT arteriograms of the head, neck and shoulder region. The results have enabled us to divide the clavicle into three zones based on the proximity and relationship of the vascular structures adjacent to it. The results show that at the medial end of the clavicle the subclavian vessels are situated behind it, with the vein intimately related to it. In some scans the vein was opposed to the posterior cortex of the clavicle. At the middle one-third of the clavicle the artery and vein are a mean of 17.02 mm (5.4 to 26.8) and 12.45 mm (5 to 26.1) from the clavicle, respectively, and at a mean angle of 50° (12 to 80) and 70° (38 to 100), respectively, to the horizontal. At the lateral end of the clavicle the artery and vein are at mean distances of 63.4 mm (46.8 to 96.5) and 75.67 mm (50 to 109), respectively. An appreciation of the information gathered from this study will help minimise the risk of inadvertent iatrogenic vascular injury during plating of the clavicle.
