CN IV Palsy Flashcards
What is the most common CN palsy?
CN IV palsy
When the the superior oblique a pure depressor?
In 37 degrees of adduction
When is the superior oblique an intorter and abductor?
In 53 degrees abducted
What is the tertiary action of the SO?
abduction
What are the 2 circumstances where the hypertropia will be worse? (signature findings)
- across from vertically limited eye
2. ipsilateral head tilty
What are the 3 steps in Parks 3-step testing?
- Check hyper in Primary Gaze
- Check hyper in right/left gaze
- Check higher in right/left head tilt
Anything greater than 10 degres of torsion for one eye is suggestive of?
Bilateral CN IV palsy
A unilateral CN IV palsy usually has how many degrees of torsion?
2-5 degrees
What are the 3 ways we can test excyclotorsion subjectively?
- Bilateral Maddox Rod
- Subjective drawing
- Bagolini Lenses
In a CN IV palsy, the eye will be intorted or extorted?
Extorted
When measuring excyclotorsion, if the objective and subjective measurement are the same this means?
Recently acquired and acute onset (possibly trauma)
When measuring excyclotorsion, if the objective finding is greater than the subjective findings this means?
Chronic palsy, longstanding
When measuring excyclotorsion, if there is no subjective finding but an objective finding this means?
Congenital/acquired in childhood
What type of lesion will cause someone to get a bilateral CN IV palsy?
Lesion at anterior medullary velum (where both nerves cross)
What is the main finding in a bilateral CN IV palsy?
Reversing hyper in right and left gaze
How long must you wait before surgery is considered for a bilateral 4th palsy?
must wait 1 year
What is the most common cause of a 4th palsy in adults and kids?
Trauma
What is the workup for a 4th nerve palsy in a 20-50 year old?
- Neuroimaging: MRI
2. Follow the patient
What is the workup for a 4th nerve palsy in a 50+ year old?
- Neuroimagin: MRI
2. Vasculopathic workup
What are the 3 ways to manage a 4th nerve palsy?
- Fresnel prisms + Patch for 9-12 months
- Monitor for 2’ contracture
- Sx = must wait 1 year
