Section X. Clinical Disorders of the Cranial Nerves and Brainstem

Answer c.

Functional visual loss commonly presents as tunnel vision.

On tangent screen testing, a circular area of constriction

that does not expand appropriately when the distance

between the patient and the tangent screen is increased is

suspicious for functional disorder.

Answer e.

A right occipital lobe infarction would result in a left hom-

onymous hemianopia. A left homonymous hemianopia

also could be seen with a lateral geniculate body lesion,

although the latter is generally incongruent.

Answer e.

The visual field examination shows bilateral enlargement

of the blind spots. This could be seen in a number of dis-

orders, but of the choices given, idiopathic intracranial

hypertension is the correct answer.

Answer b.

Patients with papilledema may present with headache,

transient visual obscurations, enlarged blind spots, and

visual field loss (usually beginning nasally) if the edema is

chronic.

Answer b.

Horner syndrome is characterized by unilateral ptosis,

miosis, and anhidrosis. It can result anywhere along the

pathway of the sympathetic axons traveling to the eye (see Figure X.A5). In the case of an extracranial carotid artery

dissection, anhidrosis is usually absent because the sudo-

motor fibers have traveled to the face along and near the

external carotid artery. Vertebral artery dissection would

result only in Horner syndrome if evidence of ischemia

was observed on MRI (lateral brainstem), and the pain is

usually posterior. Carotid-cavernous fistula also can occur

after trauma and more commonly results in eye pain, prop-

tosis, and a sixth nerve palsy. A sigmoid sinus dural arte-

riovenous fistula would typically present with pulsatile

tinnitus and would not affect the sympathetic pathway.

Answer c.

Charles-Bonnet hallucinations may occur after occipital

lobe injury and consist of well-formed hallucinations due

to deprivation of sensory input. Compared with seizures

that last from seconds to minutes, Charles-Bonnet halluci-

nations may last for hours. Hypnagogic hallucinations are

hallucinations occurring immediately before falling asleep.

Palinopsia refers to the persistence of an image after the

stimulus has been removed. Metamorphopsia is the distor-

tion of an image in time and space.

Answer d.

The combination of visual loss (branch retinal artery occlu-

sion), hearing loss, and cerebral ischemia is characteristic

of Susac syndrome. The MRI scan shows the snowball-like

appearance of ischemic changes in the corpus callosum

consistent with Susac syndrome.

Answer c.

Graves disease generally causes exophthalmos and orbital

edema before progressing to ophthalmopathy. The myopa-

thy is attributed to inflammation and fibrosis of the mus-

cles, sparing the tendinous insertions. The inferior recti

muscles usually are most severely affected (causing hypot-

ropia), followed by the medial recti, superior recti, and

oblique muscles. In thyroid ophthalmopathy, the lateral

rectus muscle is rarely affected. The most common presen-

tation is vertical diplopia caused by asymmetrical involve-

ment of the inferior or superior recti muscles. Other signs

may include orbital congestion, eyelid lag, proptosis, con-

junctival injection, and optic neuropathy due to compres-

sion of the optic nerve by enlarged extraocular muscles in

the orbital apex.

Answer b.

Gradenigo syndrome is an infectious or neoplastic pro-

cess that spreads to the tip of the petrous bone (petrous

apicitis). It can be caused by otitis media. This syndrome

may result in a sixth nerve palsy because the sixth nerve

travels through the Dorello canal along the petrous apex.

Answer d.

A pupil involving third nerve palsy is an emergency until

proven otherwise. The differential diagnosis includes

compressive causes, including an enlarging aneurysm,

pituitary apoplexy, cavernous sinus fistula, or thrombosis.

A CT angiogram of the brain helps in the evaluation for an

aneurysm and carotid sinus vascular pathologic cause.

Magnetic resonance imaging might also be helpful to eval-

uate the course of the third nerve, including assessment of

the pituitary gland.

Answer a.

The superior oblique functions to move the eye down and

inward, as well as intorsion. A patient with fourth nerve

palsy has hypertropia of the affected eye because the supe-

rior oblique is not aiding the inferior oblique to keep the

eye downward. The affected eye is slightly extorted

because of impairment of intorsion. Thus, the patient

reports skew double vision that worsens with head tilt

toward the side of the superior oblique dysfunction and

improves with head tilt to the opposite side. Trauma is a

common cause of fourth nerve palsy.

Answer c.

The presence of horizontal diplopia would be suggestive

of additional involvement of the brainstem. A recent

upper respiratory infection, abnormal head impulse test,

and unidirectional horizontal nystagmus should point

more toward a peripheral cause of vertigo. Although the

ability to walk independently is more likely to be

impaired in central vertigo than peripheral vertigo, it is

not a sensitive test.

Answer b.

Migrainous vertigo may last from 5 minutes to 72 hours.

BPPV is triggered by position change and generally lasts

seconds. It may or may not be accompanied by other

symptoms. Meniere disease is commonly associated with

hearing loss and tinnitus, in addition to episodic vertigo.

Surgery can be performed to treat patients with vertigo and

semicircular canal dehiscence.

Answer a.

All of the listed items can cause pulsatile tinnitus except

Meniere disease, which generally causes persistent non-

pulsatile tinnitus.

Answer c.

The MRI shows a flow void in the region of cranial nerve

VII. The void is the vertebral artery that swings into the

cerebellopontine angle. The term dolichoectasia refers to

an enlarged, tortuous vessel. Vertebrobasilar dolichoectasia

may cause hemifacial spasm, trigeminal neuralgia, or, occa-

sionally, paroxysmal vertigo because of compression of

these cranial nerves. These entities also may result from

ischemic stroke and hemorrhage. Magnetic resonance angi-

ography from the same patient (Figure X.A15) shows the

tortuosity of the vertebral arteries into the cerebello-pon-

tine angle.

Answer a.

The sympathetic axons and cranial nerve XII come

together in the retropharyngeal space, coursing near the

internal carotid artery. Both an internal carotid artery dis-

section and retropharyngeal abscess could result in the

described deficits. However, the acute onset is suggestive

of a vascular cause. In the retropharyngeal space, addi-

tional involvement of cranial nerves IX, X, and XI may

occur.

Answer c.

Upper respiratory infections including COVID-19 viral

infection, and sinus disease account for the majority of

cases of patients reporting anosmia. Often, the symptom is

temporary. Head trauma is a common cause of loss of

smell that is more permanent.

Answer b.

The description is of symptoms or signs suggestive of

involvement of cranial nerves IX, X, and XI. These cranial

nerves exit the jugular foramen together. Although the

nerves have components in the medulla, the spinal por-

tion of the spinal accessory nerve (cranial nerve XI) enters

the foramen magnum and exits the jugular foramen after

merging with the component of cranial nerve XI arising

from the nucleus ambiguous. It is never part of the medul-

lary parenchyma.