Anteriorly rotated side wider and closer to odontoid
Opposite side smaller and farther from odontoid
• Lateral view: ± widened atlantodental interval
• Dynamic CT: Should include occiput C1-C2
Initial scan: Maintain position of comfort
2nd scan: Rotate head to contralateral side
Interpretation: C1-C2 relationship fixed or C1 unable to rotate past neutral to contralateral side
• MR may replace CT to eliminate radiation dose
Top Differential Diagnoses
• Torticollis
Resolves within a few days to weeks
• Septic C1-C2 joint
Pathology
• Multiple theories: Common theme tracking of inflammatory mediators from upper airway
Clinical Issues
• Pain, head tilt, restricted neck movement
• Cock-robin position: Head rotated and tilted to 1 side with chin lifted to opposite side
• Associated with otitis media, pharyngitis, retropharyngeal abscess, upper respiratory infection, otolaryngologic surgery
• 68% < 12 years old; 90% < 21 years old
• Leads to permanently fixed deformity if left untreated
• Reduction and immobilization are key
(Left) Lateral radiograph shows typical retropharyngeal effusion due to strep pharyngitis . Grisel syndrome may occur with any stage of infection, from effusion to extensive abscess.
(Right) Axial CECT shows retropharyngeal space abscess due to left palatine tonsillitis . Although the C1-C2 articulation is not affected, one can appreciate how easily inflammatory changes can track to that articulation.
(Left) Sagittal STIR MR in a florid case of craniovertebral junction bacterial infection shows marked increased signal involving prevertebral space , odontoid, and loss of anterior C1 arch margin. This is to be contrasted with the less aggressive appearance of Grisel syndrome.
(Right) Axial T1 C+ MR shows infection involving the craniovertebral junction with multiple small abscesses within the posterior nasopharyngeal tissue . Note the close anatomic relationship which would allow for C1-C2 joint involvement.
TERMINOLOGY
Synonyms
• Nontraumatic atlantoaxial subluxation
• Atlantoaxial rotary fixation/subluxation
Definitions
• Atlantoaxial rotary subluxation accompanying respiratory infection or otolaryngolic surgery
IMAGING
General Features
• Best diagnostic clue
Child with fixed, rotated head soon after upper respiratory infection or otolaryngologic surgery
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. Grisel syndrome may occur with any stage of infection, from effusion to extensive abscess.
due to left palatine tonsillitis 
. Although the C1-C2 articulation is not affected, one can appreciate how easily inflammatory changes can track to that articulation.
, odontoid, and loss of anterior C1 arch margin. This is to be contrasted with the less aggressive appearance of Grisel syndrome.
. Note the close anatomic relationship which would allow for C1-C2 joint involvement.
