Neuro Ophtha 2

What percentage of "microvascular" or "vasculopathic" 3rd nerve palsies demonstrate some degree of pupil involvement?

• <1%

• 20%

• 50%

• 90%

Answer explanation

This is usually a diagnosis of exclusion made after thorough evaluation of patient for cerebral aneurysm using CT/MRI

What is the most common structural etiology causing downbeat nystagmus?

• Posterior fossa meningioma

• Chiari type I malformation

• Spinal cord/brainstem syrinx

• Cerebellar hemangioma

Answer explanation

DBN

Abnormal drift of eyes upward followed by corrective downward fast saccade.

Mostly localized to the cervicomedullary junction (CVMJ) or cerebellum (eg Arnold Chiari Type I)

Arnold Chiari Type I - cerebellar tonsil herniation through foramen magnum; may be reversible via neurosurgical decompression

What are the average diameters of optic nerve head and intraorbital optic nerve respectively?

• 1mm; 2mm

• 1.5mm; 3mm

• 3mm; 6mm

• 1cm; 2cm

Answer explanation

Simply needs to be memorized :)

A patient has right eye pharmacologically dilated, left eye undilated. Assume ha has a longstanding right RAPD from prior exams. To properly assess for RAPD in this patient, you must hold a light indirectly on the ___ eye while a direct light is swung back and forth between the eyes. In this case, the ___ pupil will dilate when direct light is swung from the ___ eye to the ___ eye.

• left, left, right, left

• left, left, left, right

• right, left, left, right

• Cannot assess RAPD in this scenario

Answer explanation

You can still assess RAPD even if one eye is pharmacologically dilated =

reverse RAPD (rRAPD).

Take note how it works

What is the primary MoA of apraclonidine?

• Beta adrenergic receptor agonist (B1 > B2)

• Alpha adrenergic receptor agonist (A2 > A1)

• Alpha adrenergic receptor agonist (A1 > A2)

• Beta adrenergic receptor agonist (B2 > B1)

Answer explanation

In individual with unilateral Horner syndrome with apraclonidine applied bilaterally, sympathetically denervated eye dilates and normal eye constricts leading to reversal of anisocoria.