Intro to Congenital Anomalies & Variants

Question 1

What is the most commonly seen x-ray “abnormality?”

Answer 1

Congenital anomalies & variants

Question 2

What are the 4 rules of anomalies?

Answer 2

1. Most commonly seen in transitional spinal areas
2. When you see 1, look for others
3. The other is usually a soft tissue abnormality
4. The hardest things to see are the things that aren’t there

Question 3

What 2 features on an x-ray may indicate a chronic (congenital) abnormality?

Answer 3

• smooth, well-rounded, corticated margins
• stress hypertrophy

Question 4

What is Mach effect?

Answer 4

Overlapping edge effect
(Eg. Incisors gap appears as dens Fx)

Question 5

What is instability?

Answer 5

Excess motion

Question 6

How is instability assessed radiographically?

Answer 6

Flexion/extension radiographs

Question 7

Name the 3 types of instability

Answer 7

• translational
• angular
• upper cervical

Question 8

What is translational instability?

Answer 8

Excessive glide

Question 9

What should you look for to identify translational instability?

Answer 9

Posterior body line

Question 10

How is translational instability defined in the cervical spine?

Answer 10

3.5mm

Question 11

How is translational instability defined in the lumbar spine?

Answer 11

4.5mm

Question 12

What is angular instability?

Answer 12

Excessive rotation

Question 13

What should you look for on a radiograph to identify angular instability?

Answer 13

Angles between end plates

Question 14

How is angular instability defined in the cervical spine?

Answer 14

11°

Question 15

How is angular instability defined from L1-L4?

Answer 15

15°

Question 16

How is angular instability defined from L4-L5?

Answer 16

20°

Question 17

How is angular instability defined from L5-S1?

Answer 17

25°

Question 18

What is upper cervical instability?

Answer 18

Excessive sagittal plane motion at C1/C2

Question 19

What are the symptoms of upper cervical instability?

Answer 19

Very vague, may have neck pain & headache

Question 20

How is upper cervical instability diagnosed?

Answer 20

X-ray

Question 21

What are the 2 biggest players in upper cervical instability?

Answer 21

• transverse ligament (laxity, torn, destruction)
• odontoid/dens

Question 22

How many differential diagnoses can affect the transverse ligament, causing upper cervical instability?

Answer 22

26+

Question 23

Name the differential diagnoses for upper cervical instability involving the odontoid.

Answer 23

• Os odontoideum
• type 2 dens Fx
• odontoid agenesis

Question 24

When assessing for upper cervical instability, what should you look for first?

Answer 24

Anterior or posterior translation of C1 relative to C2

Question 25

When assessing for upper cervical instability, if C1 has moved anteriorly relative to C2, what do you look for next?

Answer 25

ADI
- increased = transverse lig. (26+ DDx)
- normal = dens (3 DDx)
- none = dens agenesis

Question 26

What does it mean if C1 has translated posteriorly relative to C2?

Answer 26

Always a dens problem (3 DDx), because normal dens shouldn’t allow C1 to move posteriorly

Question 27

What is the normal ADI measurement for adults and children?

Answer 27

Adult (>16yrs): 3mm or less
Child: 5mm or less

Question 28

Your patient has non-traumatic neck pain, and radiographs show a posterior shift of C1. What is your recommendation for this patient?

Answer 28

Neurosurgical referral
(DDx list = type 2 odontoid fx, os odontoideum)

Question 29

Your patient was in a motor vehicle accident and has neck pain. Radiographs show a posterior shift of C1. What is your recommendation for this patient?

Answer 29

emergency transport
(DDx = type 2 odontoid fx, os odontoideum)