- Discussion:
-
flexion-extension laterals;
- prior to intubation for elective surgery, all patients at risk should have
flexion extension laterals of cervical spine r/o
atlantoaxial instability;
- Radiographs:
-
atlantodens interval (ADI) needs to be evaluated;
- instability is present when a
3.5 mm ADI difference on flex/ext views;
- 7 mm difference may imply disruption of the alar ligaments;
- difference of > 9 mm is associated with an increase in neurologic
injury and will usually require posterior fusion and wiring;
-
space available for cord (SAC):
- posterior space of < 13 mm is contraindication to elective surgery until
C-spine is stabilized first;
- Radiographic Evaluation:
-
Cross Table Lateral:
- McGregor's line:
- hard palate-posteror occipit curve;
- dx is based on tip of dens being > 8 mm above this line in men
and > 10 mm above the line in women;
- Ranawat's line:
- center of
C2 pedicle to the
C1 arch;
- nl is > 17 mm and < 13 mm is consistent with impaction;
- Chamberlain's line:
- anterior foramen to the top of the
C1 arch;
- if the dens is > 6 mm above this line, consistent w/ impaction;
