Radiographic assessment of basilar invagination

Case contributed by Dr Prashant Mudgal

The  radiographic assessment of basilar invagination can be assessed by observing relative position of tip of odontoid process on frontal and lateral view of skull on x ray as well as on the coronal and sagittal planes on CT. 

Coronal Image

  • Digastric line (yellow line) - tip of odontoid process is normally located 11 mm below this line.
  • Bimastoid line (blue line) - tip of odontoid process projects normally not more than 10 mm above this line.

Sagittal Image

  • McRae line (red line) - tip of odontoid process normally projects below this line
  • Chamberlain line (green line) - tip of odontoid process projects normally not more than 3 mm above this line.
PlayAdd to Share

Case information

rID: 28621
Published: 3rd Apr 2014
Last edited: 8th Dec 2015
System: Head & Neck
Tag: pm
Inclusion in quiz mode: Included

Updating… Please wait.

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.