Wackenheims line
Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical spinal canal.
Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects this line 1).
The odontoid should be tangential to or below the line that extends the course of the clivus (the clivus baseline). If the clivus is concave or convex, this baseline is drawn to connect the basion to the base of the posterior clinoid process on the clivus 2).
1)
Kwong Y, Rao N, Latief K. Craniometric measurements in the assessment of
craniovertebral settling: are they still relevant in the age of cross-sectional
imaging? AJR Am J Roentgenol. 2011 Apr;196(4):W421-5. doi: 10.2214/AJR.10.5339.
PubMed PMID: 21427306.
2)
VanGilder JC, Menezes AH, Dolan KD. In: Radiology of the Normal Craniovertebral Junction. The Cranio- vertebral Junction and Its Abnormalities. NY: Futura Publishing; 1987:29–68