MCQs on Cerebrovascular Disorders

Written by Dr. James Whitfield (MBBS, FRACGP) – General Practitioner

Question 1

A 56-year-old man presents to the emergency department with complaint of diplopia. On examination, he has right-sided ptosis. His visual acuity and visual fields are unaffected. His right eye is depressed inferiorly and laterally and he is not able to look to the left side. The pupillary light reflex of the right eye is sluggish. The neurological examination is otherwise unremarkable.

Which one of the following can be the most likely cause of this presentation?

A) Midbrain infarct
B) Right 6th nerve palsy
C) Posterior communicating artery aneurysm
D) Right 4th nerve palsy
E) A lesion in the occipital cortex

Correct Answer: C) Posterior communicating artery aneurysm

This patient has the classic presentation of a third cranial nerve (oculomotor) palsy. The third cranial nerve innervates the levator palpebrae superioris (which elevates the eyelid) and four extraocular muscles: the medial rectus (adduction), superior rectus (elevation), inferior rectus (depression), and inferior oblique (elevation and extorsion). It also carries parasympathetic fibers that control pupillary constriction and lens accommodation.

Involvement of the pupil (sluggish pupillary light reflex) strongly suggests a compressive lesion, particularly an aneurysm. The posterior communicating artery (PComA) is the most common site of an aneurysm causing a compressive third nerve palsy. This is a neurological emergency, as such aneurysms are at risk of rupture and can result in subarachnoid hemorrhage.

Option A: A midbrain infarct may cause a third nerve palsy, but ischemic lesions typically spare the pupil due to the peripheral location of parasympathetic fibers. Also, an isolated cranial nerve III palsy without other midbrain signs is unlikely.
Option B: A sixth nerve palsy presents with horizontal diplopia, particularly when looking to the affected side. It does not cause ptosis or pupillary abnormalities.
Option D: A fourth nerve palsy causes vertical diplopia, especially when looking down and in. It does not cause ptosis or pupillary changes.
Option E: A lesion in the occipital cortex affects vision (acuity or fields), not extraocular movements or eyelid function.

The presence of ptosis, extraocular muscle dysfunction, and pupil involvement together point most strongly toward a compressive third nerve lesion such as a posterior communicating artery aneurysm.

Question 2

You are assessing Tim, a 65-year-old man who is brought to the emergency department after his wife suspected there may be something wrong with him. She noticed that he had been shaving only the right side of his face for the past two days. Assessment suggests ischemic stroke, and you are performing a neurological examination on him.

In the physical examination, when you ask him to lift his left arm, he raises his right arm instead.

Which one of the following areas is most likely to have been affected by the stroke?

A) Right frontal cortex
B) Left temporal cortex
C) Right parietal cortex
D) Left parietal cortex
E) Right occipital cortex

Correct Answer: C) Right parietal cortex

The scenario represents a classic case of hemineglect, also known as unilateral spatial neglect or unilateral inattention. Hemineglect is a disabling condition that typically results from damage to the non-dominant (usually right-sided) cerebral hemisphere, especially the right posterior parietal cortex.

Patients with this syndrome fail to attend to the side opposite (contralateral) to the lesion. They may collide with objects on the neglected side, ignore food on one side of the plate, and neglect grooming tasks like shaving only half the face. In this case, the patient is neglecting his left side, evident from not shaving the left side of his face and lifting his right arm instead of the left arm when instructed—indicating he is unaware of the left side of his body.

Right parietal lobe pathology is the most likely explanation. Ischemic strokes affecting the parietal lobe, particularly in the territory of the middle cerebral artery, often result in this pattern.

Other options:

A) Right frontal cortex: Lesions may cause disinhibited speech and behavior, primitive reflexes (e.g., grasping, sucking), impaired judgment, contralateral weakness (more in legs), and cortical sensory deficits. Not consistent with neglect symptoms.
B) Left temporal cortex: May cause language and speech problems, forgetfulness, and visual disturbances—none of which explain this patient’s presentation.
D) Left parietal cortex: Would result in right-sided neglect. This patient is exhibiting left-sided neglect, so the lesion cannot be in the left parietal lobe.
E) Right occipital cortex: Lesions here usually present with contralateral homonymous hemianopsia, cortical blindness, and visual agnosia. These are not the primary features in this case.

Note: Spatial neglect may involve not only sensory and motor neglect but also perceptual, representational, visuospatial, and behavioral deficits.

Question 3

A 72-year-old man is being assessed for memory loss. On mini mental status exam (MMSE), he cannot answer two questions because of sight impairment. At the end of the test, his score is 23. Which one of the following would be the most appropriate next step in management?

A) Start him on donepezil.
B) Perform another cognitive assessment.
C) CT scan of the head.
D) MRI of the head.
E) Reassure.

Correct answer: B) Perform another cognitive assessment.

MMSE is a practical screening test to evaluate cognitive impairment in older adults. A score of 24 or above rules out cognitive impairment.

Sight impairment can affect the results of MMSE (or similar tools) and may lead to falsely decreased scores. Sight impairment not only affects completion of tasks requiring vision, such as copying a pentagon, but it also has been shown to be associated with impairment in performing tasks that do not require vision.

In those with sight impairment, it is suggested that the test be repeated after the sight is corrected, or other tests in which vision is not essential for reliable results are used.

With intact sight, the MMSE score of this patient would increase to at least 25; a score that excludes cognitive impairment and overrules the previous score of 23, which is indicative of mild impairment. Therefore, this patient can be safely reassured as not having cognitive impairment.

Previous Next

1. Neurology Module

1.1 Cerebrovascular Disorders

1.2 Cranial Nerves

1.3 Spinal Cord

1.4 Peripheral Nerves

1.5 Headaches

1.6 Seizure Disorders

1.7 Movement Disorders

1.8 Neuroimaging

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