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Age / Sex : 34 / F
Age/Sex: 34/F
C.C.: Posterior neck pain after traffic accident
1) What is your impression?
Courtesy : Suk-Joo Hong, MD, Korea University Guro Hospital
Diagnosis: Atlanto-occipital assimilation(=occipitoatlantal fusion)
Discussion
Findings:
- Plain radiography: basilar invagination, indetermination of atlas & occipital condyle
- CT: fusion between occipital condyle & lateral mass of C1
Differential Diagnosis:
- D/Dx. of Basilar Invagination: Atlanto-occipital assimilation Occipital condylar hypoplasia Basiocciput hypoplasia Achondroplasia, SED, Morquio syndrome, etc.
- D/Dx. of Basilar Impression (Acquired form of basilar invagination) : Paget’s disease, Osteogenesis Imperfecta, Ricketsts/ Osteomalacia, Hyperparathyroidism, Fibrous dysplasia, Rheumatoid arthritis, etc.
Diagnosis: Atlanto-occipital assimilation, partial
Discussion:
- Partial or total fusion of the atlas to the occiput
- Posterior Elements of the atlas: may be hypoplastic and anomalous
- Associated with basilar invagination & C2 ~ C3 fusion (Klippel-Feil syndrome) (70%), Chiari type I malformation with syringomyelia, Atlantoaxial subluxation (50%)
- Associated with syndrome: Achondroplasia, diastrophic dwarfism, SED, Larsen syndrome, Morquio syndrome
- Management : Cervical collars and traction: may initially be helpful, instability at the atlantoaxial junction : Decompression of posterior elements: in posterior impingement. * Basilar invagination/ Impression
- The floor of the skull is indented or has been violated by the upper cervical spine, usually the odontoid, which may sit within the foramen magnum
- The tip of dens is >5mm above the Chamberlain’s line, >7mm above the McGregor’s line
References:
1. Guille JT, Sherk HH. Congeital osseous anomalies of the upper and lower cervical spine in children. JBJS Am. 2002;84-A(2):277-288
2. Ross JS, Brant-Zawadzki M, Moore KR, Crim J, Chen MZ, Katzman GL. Congenital and developmental disorders. In: Diagnostic imaging: spine. Amiris, 2004.
3. David KM, Crokckard HA. Congenital malformations of the base of the skull, atlas, and dens. In: Clark CR, ed. The cervical spine, 4th ed. Philadelphia: JB Lippincott, 2004.
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