(1,3) C2 Anomalies Flashcards
What is spina bifida Vera?
Wide bony defect of posterior elements diagnosed in utero, which allows herniation of meninges & contents outside of the spinal canal (meningocele or myelomeningocele)
What is spina bifida occulta (SBO)?
Failure to unite the 2 halves of the posterior arch
When is a case of spina bifida occulta clinically significant?
Multiple (3+) in the same region = possible underlying neurologic problems
What are the radiographic findings of SBO on an AP view?
Vertical cleft in posterior elements
What are the radiographic findings of SBO on a lateral view?
- Absent spinolaminar junction line
- anterior arch (stress) hypertrophy
What are the most common locations of SBO?
transitional regions
(S1, C1, L5, T12, L1)
What is the clinical significance of this condition?
No clinical significance
(<3 SBO in same region)
What is an os odontoideum?
odontoid is separated from C2 vertebral body (free-floating ossicle)
How is an os odontoideum differentiated from a type 2 odontoid fracture?
smooth, well-rounded, corticated margins
What is the clinical presentation of a patient with an os odontoideum?
most often clinically silent, but may have neck pain & headahces
What is the stability of an os odontoideum?
unstable upper c/s
(always)
What is the clinical significance of an os odontoideum?
Concern for Guillotine effect:
post. arch of C1 moves anteriorly, trapping spinal cord against anterior tubercle
What is the normal average diameter of the dens?
8mm
What is Steele’s rule of thirds?
The dens, spinal cord, and CSF each take up 1/3 of the spinal canal of C1. Therefore the dens can move 8mm before impacting the cord.
What are your next steps if you suspect your patient has an Os odontoideum?
- flexion/extension radiographs
- neurological consult
What is considered the body’s “protective” mechanism for an Os odontoideum?
Steele’s rule of thirds
What is the diagnosis?
Os odontoideum
What is the diagnosis?
Os odontoideum
What is an Os Terminale of Bergmann?
un-united secondary ossification center at tip of odontoid
What is the stability of an Os terminale of Bergmann?
stable
(incidental finding)
What are the radiographic findings of an Os terminale of Bergmann?
V-shape appearance on tip of dens
What is the diagnosis?
Os Terminale of Bergmann
What is odontoid hypoplasia?
failure of odontoid to ossify (partial formation of odontoid)
In a patient with odontoid hypoplasia, what would indicate instability?
lateral shift of atlas relative to axis
