Neuroophthalmology Flashcards
- The horizontal gaze center is formed by
which one of the following:
a. Pontine paramedian reticular formation
b. Reticular medial longitudinal fasciculus
c. Preganglionic Erdinger-Westphal nucleus
d. Brodman Area 6
e. Superior colliculus
a. Pontine paramedian reticular formation
Gaze is a complex eye movement that is mainly controlled by the combination of CNs III, IV, and VI. Gaze can be simply classified as lateral, vertical, or conjugate. The frontal eye field (Area 8) and supplementary eye field (Area 6) are regions of the cerebral cortex that control gaze, and they innervate the contralateral paramedian pontine reticular formation (PPRF). Fibers from the PPRF reach the ipsilateral CN VI nucleus and contralateral CN III nucleus through the contra- lateral MLF to control lateral gaze. Lateral gaze palsies are classified as internuclear ophthalmo- plegia (INO), lateral gaze palsy, or one-and-a- half syndrome, and the corresponding lesions are located in the MLF, PPRF, and both MLF and PPRF, respectively. In INO, lesions in the
MLF cause ipsilateral eye adduction failure. The contralateral eye can abduct, but with nys- tagmus. In lateral gaze palsy, lesions in the PPRF cause ipsilateral eye abduction and contralateral eye adduction failure. Lateral gaze to the contra- lateral side is preserved in these cases. Lesions in both the MLF and the PPRF result in ‘one- and-a-half’ syndrome with ipsilateral eye abduction and adduction failure and contralateral eye adduction failure. The contralateral eye can abduct, but with nystagmus. The control center for vertical gaze is located at the rostral interstitial nucleus of the MLF, near the CN III nucleus in the midbrain. In addition, it has been suggested that a center for convergence is located near CN III nucleus. A lesion in the midbrain can cause vertical gaze palsy and convergence palsy, and this is known as Parinaud syndrome.
A 25-year-old woman presents with a several
week history of diplopia, with an 8 month history of generalized headache which has been
particularly bad over the last 2 months. On
examination sheis obese, has a normal pupillary
light reflex and no RAPD. Appearance of
fundi are shown. Which one of the following
is most likely cause of her complaint?
a. Non-organic disorder
b. Optic nerve drusen
c. Optic neuritis
d. Idiopathic intracranial hypertension
e. Leber’s hereditary optic neuropathy
d. Idiopathic intracranial hypertension
the optic nerve head and usually results in bilateral optic disc swelling. The optic disc may be markedly elevated, with hemorrhages of the nerve head and surrounding retina. Usually, there is no visual loss acutely, except for enlargement of the physiologic blind spot from elevation and compression of the peripapillary retina. Chronic papilledema can cause loss of the peripheral visual field, with central vision
affected only very late in its course. IIH typically occurs in obese women between puberty and men- opause. Men and non-obese women frequently harbor identifiable causes of elevated intracranial hypertension (e.g. Chiari malformation, occult dural arteriovenous malformation, dural venous sinus occlusion, sleep apnea) and should not be con- sidered to have IIH until an exhaustive clinical investigation confirms that there is no identifiable cause. Fundoscopic features of papilledema are highlighted below.
A 50-year-old man complains of 2 days’ double vision. Has abducting nystagmus in the
right eye and vertical gaze is preserved bilaterally. Which one of the following is most
likely?
a. Left internuclear ophthalmoplegia
b. Orbital apex syndrome
c. Left incomplete oculomotor palsy
d. Superior orbital fissure syndrome
e. Left one-and-a-half syndrome
a. Left internuclear ophthalmoplegia
A 53-year-old woman reports drooping of her eyelids for the last 6 months. She experiences diplopia when driving for any extended period of time. Which one of the following is most likely?
a. Cavernous sinus thrombosis
b. Myasthenia gravis
c. Oculomotor nerve palsy
d. Pituitary apoplexy
e. Thyroid ophthalmopathy
b. Myasthenia gravis
Ocular myasthenia gravis can mimic an isolated or combined neuropathy of CN III (except pupil involvement), IV, or VI, but often presents with diplopia or ptosis that is not easily categorized. Ocular involvement is seen early and may be the only system affected in some patients, with an inability to forcefully close their eyes against resis- tance. Patients frequently report worsening symp- toms as the day progresses and relief after a nap or rest. The diagnosis is sometimes difficult to make because the results of edrophonium chloride (Tensilon) testing, serum acetylcholine receptor antibody assay, repetitive electromyographic nerve stimulation, or trials of pyridostigmine bro- mide (Mestinon) may be equivocal. The ice test is also a useful screen. Single-fiber electromyogra- phy has the greatest sensitivity and specificity but is technically difficult. CT of the thorax is per- formed to exclude a thymoma.
Forty minutes after bilateral instillation of
10% cocaine eyedrops, the left pupil dilates, but the right does not.
a. Horner’s syndrome
b. Myasthenia gravis
c. Oculomotor palsy
d. Trochlear palsy
e. Thyroid ophthalmopathy
a. Horner’s syndrome
Right Horner’s syndrome with right ptosis, miosis and facial anhidrosis due to right lateral medullary infarction. Relative miosis and a slight ptosis (1-2 mm) may result from interruption of the oculosym- pathetic pathway anywhere along the three-neuron chain: from the hypothalamus to the ciliospinal center of Budge-Waller (C8–T1), across the lung apex to the superior cervical ganglion, or from the superior cervical ganglion by means of the carotid plexus sympathetic nerves to the pupillary dilator. Postganglionic interruption (at or distal to the superior cervical ganglion) is commonly benign or idiopathic, but preganglionic or central oculosympathetic pareses are associated with malignancy in about half the cases.
Pharmacologic evaluation in Horner’s syndrome
(1) Apraclonidine0.5%isadirectalpharecep- tor agonist. It does not cause pupil dilata- tion in the presence of an intact sympathetic innervation, but will dilate any pupil with sympathetic denervation. In Horner’s it will thus reverse the aniso- coria and elevate the ptotic lid.
(2) Cocaine 10% dilates the normal (non- Horner’s) pupil by blocking the reuptake of norepinephrine into sympathetic nerve endings producing a prolonged mydriasis over 45 min. Due to the lack of norepi- nephrine in sympathetic denervated pupil (Horner’s) blocking reuptake does not produce a mydriasis. Persistence/wors- ening of anisocoria establishes the diagnosis.
(3) Hydroxyamphetamine actively releases norepinephrine from adrenergic nerve endings to dilate a normal pupil. In Hor- ner’s syndrome due to first- or second- order neuron damage, intact third-order neurons will respond to hydroxyampheta- mine as those in a normal pupil and dilate. However, with Horner’s due to a third- order (postganglionic) lesion, the damaged nerve endings cannot release norepineph- rine and the pupil will not dilate.
A 22-year-old female complains of reduced
vision and pain in the left eye starting 3 days
ago. On examination vision is normal in the
right eye but 6/12 (20/40) in the left eye, Left
relative afferent pupillary defect, pain when
looks to right orleft, no redness or photophobia.
a. Arteritic anteriorischemic optic neuropathy
b. Central retinal artery occlusion
c. Iritis
d. Optic neuritis
e. Orbital cellulitis
d. Optic neuritis
UK (6 m) 6/6 6/9 6/12 6/18 6/24 6/36 6/60
US (20 ft) 20/20 20/30 20/40 20/60 20/80 20/120 20/200
A 34-year-old man present with intermittent diplopia, worse when looking to the left. Exa- mination findings are shown below. Which one of the following is most likely?
a. Left abducens nerve palsy
b. Left conjugate gaze paresis
c. Left internuclear ophthalmoplegia
d. Left hypotropia
e. Right trochlear palsy
a. Left abducens nerve palsy
Trauma is a common cause of abducens palsy in all age groups. Acute, painful abducens paresis in a patient 45 years or older who has hypertension or diabetes suggests an ischemic cranial mono- neuropathy. Recovery over a period of 2-6 months is the rule. In young patients, abducens palsies may occur as a postviral syndrome, but the clinician must remain alert for the possibility of tumor. Elevation of intracranial pressure can affect the function of one or both VI nerves.
On examination, this 15-year-old boy was found to have upgaze paresis, ocular tilt reaction (right superior rectus skew devia- tion and head tilt), papilledema, and aniso- coria. The pupils were moderate in size and poorly reactive to light, but reactive to near stimuli.
a. Adie’s tonic pupil
b. Argyll Robertson pupil
c. Horner syndrome
d. Parinaud syndrome
e. Wallenberg syndrome
d. Parinaud syndrome
Dorsal midbrain syndrome (Parinaud’s syndrome) consists of upgaze palsy, convergence spasm or paresis, bilateral mid-dilated pupils with light- near dissociation (poor reaction to light and good reaction to near), and convergence-retraction nystagmus. The nystagmus is unique to this syn- drome and consists of rapid convergence with retraction of the globes on attempted upgaze. Common causes include pinealomas, aneurysms of the vein of Galen, and noncommunicating hydrocephalus with distention of the third ventri- cle and the anterior aqueduct of Sylvius. This syn- drome may also occur with stroke as one of the “top of the basilar” syndromes.
Which one of the following is the most likely
cause of this patient’s Horner’s syndrome?
a. Urinary Bence-Jones protein
b. Urinary catecholamines
c. Urinary ketones
d. Urinary casts
e. Urinary protein/creatinine ratio
b. Urinary catecholamines
Horner’s syndrome in children may be caused by
neuroblastomas, and 50% are adrenal in origin.
An 82-year-old man had sudden, profound vision loss in his right eye. This was preceded by 2 days of brief episodes of transient vision loss in the affected eye lasting seconds. He also complained of “tender cords” on his scalp, jaw claudication, and weight loss. The erythrocyte sedimentation rate (ESR) was normal and fundoscopy showed a dif- fusely swollen right optic disc.
a. Anterior ischemic optic neuropathy
b. Iritis
c. Central retinal artery occlusion
d. Central retinal vein occlusion
e. Optic neuritis
a. Anterior ischemic optic neuropathy
This is the commonest cause of acute visual loss in older patients, and thought to be due to ischemia in posterior circulation of the gobe—predomi- nantly vessels supplying the optic nerve at its exit from the eye. It is classified as non-arteritic or arteri- tic, the former being much more common. In all cases of AION, it is vital to determine whether there is any evidence of an arteritic cause (e.g., giant cell arteritis). Untreated giant cell arteritis can cause rapid, sequential, or simultaneous blindness in both eyes. If giant cell arteritis is suspected because of an elevated ESR or CRP, or both, or because of symptoms such as headache, scalp and temple tenderness, myalgias, arthralgias, low-grade fever, anemia, malaise, weight loss, anorexia, or jaw clau- dication, oral or intravenous steroid treatment should be instituted immediately. In acute cases, the patient may benefit from high-dose intravenous steroids. Biopsy of the temporal artery should follow within days of steroid therapy. In arteritic AION, the visual loss is usually profound, and the optic nerve is often diffusely swollen and pale.
Which one of the following is the most likely cause of this patient’s Horner’s syndrome?
a. Carotid dissection
b. Congenital
c. Neuroblastoma
d. Hypothalamic tumor
e. Cervical cord ependymoma
b. Congenital
Iris heterochromia in idiopathic congenital
Horner’s syndrome.
A54-year-old male presented after being told he had unequal pupils by a colleague. Examination findings are shown to light, accom- modation and 30 min after administration of 0.1% pilocarpine to both eyes. Which one of the following is most likely?
a. Left Argyll Robertson pupil
b. Left Horner’s syndrome
c. Right Adie’s tonic pupil
d. Right oculomotor palsy
e. Right relative afferent pupillary defect
c—Right Adie’s tonic pupil
The right pupil is mid-sized and larger than the
left, poorly reactive to light, but reactive to near
stimulus (light-near dissociation). It constricted
with 0.1% pilocarpine while the left pupil did
not indicating denervation hypersensitivity on
the right. Adie’s (or Holmes-Adie’s) syndrome which
is a symptom complex consisting of tonic pupil(s)
and absent deep tendon reflexes and is the commonest cause. Viral or bacterial infection causing
inflammation to the ciliary ganglion damages parasympathetic postganglionic input to the eye, and to
dorsal root ganglia in the spine. The use of stronger
1% pilocarpine would be effective in constricting
normal pupils, as well as third nerve-related mydriasis, tonic pupils, and other pre- and postganglionic
parasympathetic disorders because in these cases
the receptors at theiris constrictormuscle are either
normal or hypersensitive. Pupils dilated with anticholinergic agents such as atropine, tropicamide, or
cyclopentolate or sympathomimetic agents such as
phenylephrine or neosynephrine, are generally
large (> 7-8 mm) and unreactive to light or near
stimulation.
A 69-year-old presented with recurrent falls and unsteadiness. Visual acuity is normal. Examination findings are shown to at rest, to light and to accommodation. Which one of the following is demonstrated?
a. Adie’s tonic pupil
b. Argyll Robertson pupils
c. Parinaud syndrome
d. Marcus-Gunn pupil
e. Marcus-Gunn phenomenon
b—Argyll Robertson pupils
Here the pupils are bilaterally small and show lightnear dissociation (“accommodate but do not
react”). Apart from pupil size, the other main way
of differentiating between Argyll Robertson pupils
and Adie’s pupil is their speed of constriction to
near vision—immediate in the former and slow/
prolonged in the latter. In tabes dorsalis (demyelination secondary to syphilis)ArgyllRobertson pupils
are associatedwith absent deep tendon reflexes,loss
of vibratory sense and proprioception in the lower
extremities, and Charcot joints.
A 5-year-old child presents with diplopia and numbness over right forehead. Examination findings shown in primary gaze, down gaze, left gaze and right gaze. Which one of the following are most likely?
a. Gradenigo’s syndrome
b. One-and-a-half syndrome
c. Orbital apex syndrome
d. Parinaud’s syndrome
e. Third nerve palsy
c—Orbital apex syndrome
A 17-year-old presents after a head injury with diplopia, particularly worse when walk- ing down stairs and two images are oblique to each other. Examination findings are shown
in right gaze, primary gaze, left gaze, right head tilt, left head tilt and at rest. Which one of the following is most likely?
a. Left abducens palsy
b. Left fourth nerve palsy
c. Left hypotropia
d. Right exotropia
e. Right fourth nerve palsy
b—Left fourth nerve palsy
The main causes are head trauma, microvascular
infarction, congenital, tumors and demyelination.
It is the only cranial nerve which exits the brainstem dorsally (has the longest intracranial course),
it decussates to supply the contralateral superior
oblique muscle and is enveloped in the anterior
medullary velum where it is vulnerable to head
trauma. Assessment of a trochlear nerve palsy is
challenging, but a three step test is best used:
(1) Which eye is hypertropic in primary gaze?
(2) Is the hypertropia worse inleft or right gaze?
(3) Is the hypertropia worse in left or right
head tilt?
The left hypertropia, which is worse in right gaze and left head tilt, is consistent with weakness of the left superior oblique muscle. The trochlear nerve innervates the superior oblique muscle and because of its redirection at the trochlea and attachment to the globe it intorts, depresses, and abducts the eye.When the globe is adducted, however, the angle of the muscle’s insertion minimizes
all actions except pure depression. This fact simplifies clinical evaluation of the superior oblique muscle; the clinician looks at how well the right eye can move down in left gaze and how well the left eye moves down in right gaze. The vital role of the superior oblique muscle in ocular cyclotorsion explains why patients with trochlear palsy often describe diplopia with one image tilted.
One can occasionally elicit which fourth nerve is affected by asking the patient to look at a horizontal straight object (e.g. a pen). If the patient sees two images, they can be asked to describe how they intersect. A patient with a unilateral fourth nerve palsy will see a horizontal line and a tilted line below it, intersecting on the side of the abnormal
eye (the arrow points to the side of the affected
fourth nerve).
Which one of the following is most likely in the images below?
a. Cavernous sinus syndrome
b. Internuclear ophthalmoplegia
c. Left oculomotor nerve palsy
d. Left trochlear nerve palsy
e. Right Horner’s syndrome
c—Left oculomotor nerve palsy
The left eye has complete ptosis, defective
elevation, absent adduction, a down and out position in primary gaze with a large unreactive pupil,
intact abduction, and deficient downgaze. The
oculomotor nerve innervates all the extraocular
muscles (including the levator palpebrae), except
for the lateral rectus (VI) and superior oblique
muscles (IV). It also carries parasympathetic
efferent fibers to the pupillary sphincter and
ciliary muscle through the ciliary ganglion.
Complete third cranial nerve palsy produces an
eye that is turned down and out (because of
remaining function of the superior oblique and
lateral rectus muscles) and a dilated pupil with
ptosis. Partial or incomplete paresis may present
a more confusing picture. The pupillary fibers
run superficially in the nerve and are preferentially affected by compression, such as from a posterior communicating artery aneurysm or uncal
herniation. Ischemic cranial mononeuropathy of
the vasa nervosum of the oculomotor nerve
generally shows relative pupillary sparing with
the pupil being less affected than motility. Aberrant regeneration after disruption of the axons
of the oculomotor nerve may produce clinical
signs pupillary constriction or lid elevation with
attempted adduction or paradoxical motility.
Aberrant regeneration never occurs with an
ischemic (diabetic) mononeuropathy and always
implies that the nerve has been injured in such
a way that the myelin sheath and perineurium
have been breached (i.e., aneurysm, tumor, or
trauma).
Which one of the following is the most likely cause?
a. Bilateral internuclear ophthalmoplegia
b. Left internuclear ophthalmoplegia
c. Light-near dissociation
d. Left one-and-a-half syndrome
e. Tabes dorsalis
d—Left one-and-a-half syndrome
On attempted right gaze, the patient has a left
internuclear ophthalmoplegia (defective adduction of the left eye and abducting nystagmus of
the right eye). On attempted left gaze there is a
conjugate gaze paresis so that neither eye can
move past midline. This is due to a lesion in the
pons affecting the left PPRF and MLF.
