C1 Anomalies

Question 1

When looking at a lateral view x-ray of the cervical spine, you notice there is no spinolaminar junction line at C1, and the anterior tubercle seems abnormally large. What is the diagnosis?

Answer 1

Spondyloschiesis (technical name)
(=SBO at C1, can just call it an SBO)

Question 2

A patient with spondylosciesis is predisposed to what?

Answer 2

Jefferson Fx

Question 3

What other anomaly is often associated with spondylosciesis?

Answer 3

Occipitalization

Question 4

What are the 2 forms of posterior arch agenesis?

Answer 4

partial or complete

Question 5

What is the differential diagnosis for posterior arch agenesis?

Answer 5

osteolysis

Question 6

Where does posterior arch agenesis occur?

Answer 6

only in C1

Question 7

How is posterior arch agenesis differentiated from osteolysis?

Answer 7

• stress hypertrophy of anterior tubercle
• C2 megaspinous

Question 8

If you discover your patient has posterior arch agenesis, what is your next step?

Answer 8

flexion/extension views for transverse ligament insufficiency

Question 9

What other anomalies are associated with posterior arch agenesis?

Answer 9

• C2-C4 congenital block vertebrae
• Klippel-Feil Syndrome

Question 10

Name 2 radiographic findings.

Answer 10

(Posterior arch agenesis)
- stress hypertrophy of ant. Tubercle
- C2 megaspinous

Question 11

What follow up (if any) is needed?

Answer 11

(Posterior arch agenesis)
Flexion/extension radiographs for transverse ligament insufficiency

Question 12

What is the diagnosis, and what is the clinical significance?

Answer 12

(Partial) posterior arch agenesis
Transverse ligament insufficiency

Question 13

What is the diagnosis?

Answer 13

(Partial) Posterior arch agenesis

Question 14

What is a posterior ponticulum?

Answer 14

ossification of oblique part of atlantooccipital membrane (aka arcuate lig. of C1) which bridges the post. lateral mass and post. arch

Question 15

What are the 2 possible forms of a posterior ponticulum?

Answer 15

partial or complete

Question 16

What is the clinical significance of a posterior ponticulum?

Answer 16

Questionable
- possible correlation w/ migraines
- no evidence for VBA stroke risk

Question 17

What is the diagnosis?

Answer 17

Posterior ponticulum

Question 18

What is the diagnosis?

Answer 18

Lateral ponticle

Question 19

What is a lateral ponticle?

Answer 19

Ossification in the oblique occipital membrane as it passes laterally from the superolateral aspect of atlas to the TP

Question 20

What are the radiographic features of a lateral ponticle?

Answer 20

(seen only on APOM)
curvilinear ossification between TP and lat. mass of C1, often forming a distinct foramen (full circle)

Question 21

What is the clinical significance of a lateral ponticle?

Answer 21

none

Question 22

What is one of the most significant anomalies associated with Down Syndrome?

Answer 22

transverse ligament anomaly (lig. laxity or dens abnormality; 20% of pts) causing atlantoaxial instability

Question 23

What is another name for Down Syndrome?

Answer 23

Trisomy 21

Question 24

What radiographic finding is commonly seen in patients with Down Syndrome?

Answer 24

increased ADI
(>2mm adult)
(>5mm child)

Question 25

What is the cutoff age between child and adult for ADI measurements?

Answer 25

16 years

Question 26

What is needed before providing neck treatment to a patient with Down Syndrome?

Answer 26

5-view c/s radiographs

Question 27

What MRI sequence was used?

Answer 27

T2

Question 28

What 2 diagnoses are present?

Answer 28

• Occipitalization
• SBO

Question 29

What 2 diagnoses are present?

Answer 29

• Occipitalization
• SBO

Question 30

What is the diagnosis?

Answer 30

Chiari malformation

Question 31

Name 2 findings at C1, and the diagnosis.

Answer 31

SBO
- Stress hypertrophy of ant. tubercle
- absent spinolaminar junction line

Question 32

What is the diagnosis?

Answer 32

Posterior arch agenesis