Intro to Congenital Anomalies & Variants Flashcards
What is the most commonly seen x-ray “abnormality?”
Congenital anomalies & variants
What are the 4 rules of anomalies?
- Most commonly seen in transitional spinal areas
- When you see 1, look for others
- The other is usually a soft tissue abnormality
- The hardest things to see are the things that aren’t there
What 2 features on an x-ray may indicate a chronic (congenital) abnormality?
- smooth, well-rounded, corticated margins
- stress hypertrophy
What is Mach effect?
Overlapping edge effect
(Eg. Incisors gap appears as dens Fx)
What is instability?
Excess motion
How is instability assessed radiographically?
Flexion/extension radiographs
Name the 3 types of instability
- translational
- angular
- upper cervical
What is translational instability?
Excessive glide
What should you look at to identify translational instability?
Posterior body line
How is translational instability defined in the cervical spine?
3.5mm
How is translational instability defined in the lumbar spine?
4.5mm
What is angular instability?
Excessive rotation
What should you look for on a radiograph to identify angular instability?
Angles between end plates
How is angular instability defined in the cervical spine?
11°
How is angular instability defined from L1-L4?
15°
How is angular instability defined from L4-L5?
20°
How is angular instability defined from L5-S1?
25°
What is upper cervical instability?
Excessive sagittal plane motion at C1/C2
What are the symptoms of upper cervical instability?
Very vague, may have neck pain & headache
How is upper cervical instability diagnosed?
X-ray
What are the 2 biggest players in upper cervical instability?
- transverse ligament (laxity, torn, destruction)
- odontoid/dens
How many differential diagnoses can affect the transverse ligament, causing upper cervical instability?
26+
Name the differential diagnoses for upper cervical instability involving the odontoid.
- Os odontoideum
- type 2 dens Fx
- odontoid agenesis
When assessing for upper cervical instability, what should you look for first?
Anterior or posterior translation of C1 relative to C2
When assessing for upper cervical instability, if C1 has moved anteriorly relative to C2, what do you look for next?
ADI
- increased = transverse lig. (26+ DDx)
- normal = dens (3 DDx)
- none = dens agenesis
What does it mean if C1 has translated posteriorly relative to C2?
Always a dens problem (3 DDx), because normal dens shouldn’t allow C1 to move posteriorly
What is the normal ADI measurement for adults and children?
Adult (>16yrs): 3mm or less
Child: 5mm or less
Your patient has non-traumatic neck pain, and radiographs show a posterior shift of C1. What is your recommendation for this patient?
Neurosurgical referral
(DDx list = type 2 odontoid fx, os odontoideum)
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?
emergency transport
(DDx = type 2 odontoid fx, os odontoideum)
