Free Board Certified Ophthalmologist Neuro-Ophthalmology Questions and Answers

Question 1

A 62-year-old patient with poorly controlled diabetes and hypertension presents with the sudden onset of a droopy right eyelid and double vision. Examination reveals a complete ptosis and an eye that is deviated 'down and out.' The right pupil is 4mm and briskly reactive, identical to the left. Which of the following is the most likely etiology?

Accepted Answer

Microvascular ischemia

Answer

The patient presents with a classic pupil-sparing third nerve palsy. The oculomotor nerve (CN III) has pupillomotor fibers running on its periphery, which are susceptible to compression, while the main motor fibers are in the core. Microvascular ischemia, commonly due to diabetes or hypertension, affects the central, vasa nervorum-supplied part of the nerve, sparing the peripheral pupillary fibers. An aneurysm would typically compress the nerve from the outside, involving the pupil early. Cavernous sinus thrombosis would likely involve other cranial nerves (IV, V1, V2, VI). Giant cell arteritis is a less common cause and would usually present with other systemic symptoms.

Question 2

A patient undergoes automated perimetry which reveals a bitemporal hemianopia that respects the vertical midline. A lesion at which of the following locations would best explain this visual field defect?

Accepted Answer

Optic chiasm

Answer

The optic chiasm is the location where the nasal retinal fibers from each eye, which are responsible for the temporal visual fields, cross to the opposite side of the brain. A compressive lesion at the chiasm, most commonly a pituitary adenoma, will damage these crossing fibers, resulting in a loss of vision in the temporal fields of both eyes, known as a bitemporal hemianopia. Lesions of the optic nerve cause monocular field defects, while lesions posterior to the chiasm (optic tract, occipital cortex) cause homonymous hemianopias (affecting the same side of the visual field in both eyes).

Question 3

A 35-year-old woman presents with complaints of intermittent, brief episodes of vertical and torsional oscillopsia in her right eye, which she describes as 'shimmering' or 'trembling.' The episodes last for seconds at a time and are more frequent when she is tired. Her examination is normal between episodes, but during a symptomatic period, you observe a high-frequency, low-amplitude torsional movement of the right eye. What is the most likely diagnosis?

Accepted Answer

Superior oblique myokymia

Answer

Superior oblique myokymia (SOM) is a rare disorder characterized by monocular, high-frequency, low-amplitude contractions of the superior oblique muscle. This results in the classic symptoms of episodic, brief vertical and torsional oscillopsia. It typically affects healthy young to middle-aged adults. Nystagmus is typically conjugate (involving both eyes), ocular neuromyotonia involves sustained muscle contraction, and a sixth nerve palsy would present with an abduction deficit, not oscillatory movements.

Question 4

Which of the following findings is part of the classic triad for Horner's syndrome?

Accepted Answer

Ptosis

Answer

Horner's syndrome results from a disruption of the oculosympathetic pathway. The classic triad of signs consists of ipsilateral ptosis (mild drooping of the upper eyelid), miosis (a constricted pupil), and facial anhidrosis (decreased sweating). Mydriasis (pupil dilation) is the opposite of what is seen. Exophthalmos and lagophthalmos are not features of Horner's syndrome.

Question 5

A 29-year-old obese female with a BMI of 38 presents with a six-month history of daily, pulsatile headaches, transient visual obscurations, and a 'whooshing' sound in her ears. Fundus examination reveals bilateral grade 2 papilledema. According to the modified Dandy criteria, which of the following is required to confirm a diagnosis of idiopathic intracranial hypertension (IIH)?

Accepted Answer

Lumbar puncture opening pressure > 25 cm H2O

Answer

The diagnosis of idiopathic intracranial hypertension (IIH) is guided by the modified Dandy criteria. These criteria require signs and symptoms of increased intracranial pressure, no other localizing neurologic signs (except for a possible 6th nerve palsy), normal neuroimaging (no mass, and typically normal to small ventricles), and normal CSF composition. A key diagnostic criterion is a lumbar puncture opening pressure greater than 25 cm H2O in an adult.

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Free Board Certified Ophthalmologist Neuro-Ophthalmology Questions and Answers