From the Guidelines
For evaluating vertebral artery course prior to PRP injections for craniocervical instability, I recommend ordering an MRA of the head and neck with IV contrast, as it allows for better evaluation of the vessels with increased spatial resolution and decreased flow-related artifacts, as suggested by the most recent study 1. This protocol should specifically include the entire cervical spine with particular attention to the upper cervical region (C1-C2) where anatomical variations are most relevant for the procedure.
- The scan should be performed with contrast to detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web.
- Request that the radiologist provide detailed reporting on vertebral artery course, particularly noting any loops, tortuosity, or medial deviation that might place the artery at risk during needle placement.
- This imaging is crucial because vertebral artery anatomical variants are common and inadvertent arterial puncture during cervical injections could lead to serious complications including stroke.
- The scan should ideally be performed within 3 months of the planned procedure to ensure anatomical accuracy, as vascular positions can sometimes shift with progressive instability, and according to the American College of Radiology guidelines 1, MRA is a suitable imaging modality for evaluating the vertebral artery course.
From the Research
Evaluation of Vertebral Artery Course
To evaluate the vertebral artery course prior to Platelet-Rich Plasma (PRP) injections for craniocervical instability, the following options can be considered:
- CT angiography (CTA) can be used to demonstrate the vertebral arteries in relation to the cervical spine and associated pathology 2
- Digital subtraction angiography can be used to analyze the course, curvature, and termination of the vertebral artery in patients with occipital assimilation of atlas at the craniovertebral junction 3
- 3D CT angiography can be used to investigate the prevalence of vertebral artery variations and osseous anomalies in the region of the craniocervical junction 4
Magnetic Resonance Angiography (MRA) Options
For MRA, the following options can be considered:
- Time-of-flight angiography (TOF MRA) can be used as a viable alternative to contrast-enhanced MR angiography and fat-suppressed T1w images for the diagnosis of cervical artery dissection 5
- Contrast-enhanced MRA can be used, but it may not be necessary in all cases, especially if TOF MRA is available 5
Key Considerations
When evaluating the vertebral artery course, it is essential to consider the following:
- The vertebral artery has a variable course through C2 before it passes above its groove on the posterior arch of C1 4
- The presence of osseous anomalies, such as ponticulus posticus, can affect the course of the vertebral artery 4
- The use of CT angiography or digital subtraction angiography can help identify anomalous courses of the vertebral artery, which is crucial for surgical planning 2, 3