Free Board Certified Ophthalmologist Neuro-Ophthalmology Questions and Answers — 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?
- Posterior communicating artery aneurysm
- Cavernous sinus thrombosis
- Microvascular ischemia (Correct answer)
- Giant cell arteritis
Correct answer: Microvascular ischemia
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?
- Optic tract
- Optic chiasm (Correct answer)
- Occipital cortex
- Optic nerve
Correct answer: Optic chiasm
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?
- Nystagmus
- Ocular neuromyotonia
- Sixth nerve palsy
- Superior oblique myokymia (Correct answer)
Correct answer: Superior oblique myokymia
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?
- Mydriasis
- Exophthalmos
- Ptosis (Correct answer)
- Lagophthalmos
Correct answer: Ptosis
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)?
- Enlarged ventricles on MRI
- Abnormal CSF composition
- Lumbar puncture opening pressure > 25 cm H2O (Correct answer)
- Focal neurological signs other than a sixth nerve palsy
Correct answer: Lumbar puncture opening pressure > 25 cm H2O
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.
Question 6: A 58-year-old man presents with sudden, painless, severe vision loss in his left eye upon waking. His vision is counting fingers. Examination shows a relative afferent pupillary defect and a swollen, hyperemic optic disc. The contralateral eye has a small cup-to-disc ratio ('disc at risk'). Which of the following is the most likely diagnosis?
- Arteritic anterior ischemic optic neuropathy (A-AION)
- Optic neuritis
- Non-arteritic anterior ischemic optic neuropathy (NAION) (Correct answer)
- Central retinal artery occlusion (CRAO)
Correct answer: Non-arteritic anterior ischemic optic neuropathy (NAION)
This is a classic presentation for Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION), which typically causes sudden, painless, monocular vision loss, often noticed upon awakening. Key signs include optic disc edema and a contralateral 'disc at risk' (a small, crowded optic disc with little or no cupping). A-AION is less common, usually affects older patients, and is associated with systemic symptoms of giant cell arteritis. Optic neuritis typically presents with pain on eye movement and affects a younger demographic. A CRAO presents with a 'cherry-red spot' on fundus exam and optic disc swelling is not an initial feature.
Free Board Certified Ophthalmologist Neuro-Ophthalmology Questions and Answers
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?