Approach to Diplopia

Question 1

What is monocular diplopia?

Answer 1

Perception of double images when viewing with one eye.

Question 2

What are rare causes of bilateral monocular diplopia?

Answer 2

Cerebral diplopia, polyopia (can see hundreds of images), and palinopsia (ie trails).

Question 3

What tool can confirm a monocular cause of visual disturbances?

Answer 3

Pinhole occluder.

Question 4

What should be emphasized in the history for binocular diplopia evaluation?

Answer 4

Prior diplopia episodes
Childhood strabismus
Recent or remote head trauma.

Question 5

Diplopia with vertical and torsional (with lower image tilted) orientation suggests involvement of which muscle?

Answer 5

Superior oblique muscle.

Question 6

What is the likely localization of pure vertical diplopia?

Answer 6

Brainstem or cerebellar pathology.

Question 7

What does diplopia with reading or near tasks suggest?

Answer 7

Dysfunction of convergence, involving cranial nerve III or medial rectus muscle.

Question 8

What does diplopia at distance indicate?

Answer 8

Dysfunction of divergence, suggesting lateral rectus muscle or cranial nerve VI involvement.

Question 9

Diplopia onset characteristic

Answer 9

Diplopia is always sudden in onset (its either there or it isn’t).

Question 10

Diplopia/ocular misalignment not changing with gaze direction is classified as?

Answer 10

Comitant, suggesting congenital strabismus (or skew deviation if vertical).

Question 11

What does diplopia that varies with gaze direction indicate?

Answer 11

It indicates incomitant diplopia, often due to extraocular muscle dysfunction.

Question 12

What is the diagnostic yield of neuroimaging in isolated fourth, pupil-sparing third, and sixth nerve palsies?

Answer 12

Low diagnostic yield in older patients with vascular risk factors.

Question 13

What percentage of patients over 50 with one vascular risk factor had other causes of diplopia from isolated CN 4, pupil sparing 3, or 6 palsies?

Answer 13

10% had causes like neoplasm, infarction, and giant cell arteritis.

In other words, if a patient has these isolated cranial neuropathies causing diplopia with one vascular risk factor there is a good chance that it is ischemic but a small chance something else is going on. 

Question 14

What causes skew deviation?

Answer 14

Injury to the utricular-vestibular-ocular pathway in brainstem or cerebellum.

Question 15

How does skew deviation differ from cranial nerve IV palsy?

Answer 15

Vertical misalignment decreases by 50% or more in supine position compared to upright.

Question 16

Which EOM muscle does the superior branch of Cranial Nerve III innervate?

Answer 16

Superior rectus.

Question 17

What actions are performed by the superior rectus muscle?

Answer 17

Elevation, intorsion, adduction.

Question 18

Which cranial nerve branch innervates the medial rectus muscle?

Answer 18

III (Inferior branch).

Question 19

What action is performed by the inferior rectus muscle?

Answer 19

Depression, extorsion, adduction.

Question 20

Which muscle performs extorsion, elevation, and abduction?

Answer 20

Inferior oblique.

Question 21

What actions are performed by the superior oblique muscle?

Answer 21

Intorsion, depression, abduction.

Question 22

What key feature distinguishes INO from medial rectus muscle weakness?

Answer 22

Adduction with convergence is preserved in INO.

Question 23

What structure is affected in INO?

Answer 23

Medial longitudinal fasciculus.

Question 24

What does the medial longitudinal fasciculus connect?

Answer 24

Ipsilateral sixth nerve nucleus (pons) contralateral third nerve nucleus (midbrain).

Question 25

What symptoms occur with injury to the third nerve nucleus on one side?

Answer 25

In addition to ipsilateral CN3 palsy, there may be contralateral ptosis and supraduction weakness.

Question 26

What symptoms can accompany diplopia when third nerve fascicles are affected in the midbrain?

Answer 26

Ataxia, tremor, or hemiparesis (HAT).

Question 27

Isolated fourth nerve palsies are frequently caused by what condition?

Answer 27

Trauma.

Question 28

What can cause isolated sixth cranial nerve palsies to be falsely localizing?

Answer 28

Stretching of the nerve due to increased intracranial pressure.

Question 29

What anatomical structures does the sixth cranial nerve pass through?

Answer 29

Clivus, Dorello canal, petrous ridge, cavernous sinus, superior orbital fissure 

Question 30

What test is used to suggest MG by improving ocular symptoms?

Answer 30

Ice pack test applied for 2 minutes.

Question 31

What is eyelid curtaining?

Answer 31

Lifting one eyelid causes the fellow eyelid to droop.

Question 32

What is the Cogan eyelid twitch sign?

Answer 32

The upper eyelid jerks up once or twice upon returning to primary gaze from downgaze, especially if after a period of prolonged upgaze.

Question 33

Which extraocular muscle is most commonly involved in thyroid ophthalmopathy?

Answer 33

Inferior rectus muscle.

Question 34

What causes restriction of eye movements in thyroid ophthalmopathy?

Answer 34

Progressive edematous changes of the orbital musculature.

Question 35

What does idiopathic orbital myositis result in?

Answer 35

Painful, isolated extraocular muscle dysfunction.

Question 36

Which cranial nerve is most commonly affected by idiopathic orbital myositis?

Answer 36

The third cranial nerve.

Question 37

What condition can cause orbital inflammation with painful diplopia similar to Idiopathic Orbital Myositis?

Answer 37

IgG4-related disease (an immune-mediated fibro-inflammatory condition) and Orbital Lymphoma (typically older patients w/ recurrent or progressive symptoms).

Question 38

What condition may resemble idiopathic orbital inflammation in older patients?

Answer 38

Orbital lymphoma may resemble idiopathic orbital inflammation in older patients.

Question 39

What is crucial when instructing patients using an eye patch?

Answer 39

Ensure the eyelid under the patch is fully closed to prevent corneal injury.

Question 40

What is the difference between a “phoria ” and a “tropia ”? 

Answer 40

Ocular misalignment that is only present when binocular vision is interrupted = phoria Ocular misalignment that is present with both eyes open =tropia

Question 41

Will the diplopia of a fourth nerve palsy worsen with ipsilateral or contralateral head tilting?

Answer 41

The diplopia will worsen with ipailateral head tilt. 

Question 42

Convergence is intact/abnormal In an MLF lesion causing INO?

Answer 42

It is normal because the convergence mechanism bypasses the MLF. 

Question 43

What is different about the CN3 subnuclei that Innervate the superior rectus and Levator palpebra superior muscles? 

Answer 43

1. A single central caudal nucleus contributes fibers to the LPS muscles bilaterally 2. The superior rectus sub nucleus innervates the contralateral superior rectus muscle 

Question 44

What is unusual about the course of the trochlear nerve (CN 4)?

Answer 44

1. It is the only cranial nerve that exits dorsally in the brainstem 2. After exiting dorsally it wraps around the contralateral brainstem before it moves anteriorly so a left fourth nerve palsy actually comes from the right fourth cranial nerve nucleus 3. Oculusympathetic fibers travel adjacent to the fourth nerve nucleus so lesion in this region can also rarely cause a combination of Horner syndrome and contralateral fourth nerve palsy. According to a YouTube video I saw it also has the longest intracranial course of the cranial nerves and has the fewest axons of any cranial nerve. 

Question 45

What clinical symptoms can result in Alysian near the sixth nerve nucleus?

Answer 45

In addition to lateral rectus palsy, it is near the facial colliculus so could have ipsilateral facial neuropathy. It is near the paramedian Pontine reticular formation so it can also cause an ipsilateral gaze palsy.

Question 46

What eye movements and head tilt position will worsen a fourth nerve palsy?

Answer 46

The lesion causes hyperdeviation on the side of the palsy which increases in contralateral gaze and Ipsilateral head tilt.  GOTS Gaze Opposite, Tilt Same = worse The long intracranial course and relatively small caliber of the fourth nerve make its susceptible  to damage from closed head trauma 

Question 47

What does the long vertical course of CN 6 make it susceptible to?

Answer 47

Damage from increased intracranial pressure and had trauma 

Question 48

Approximately what percent of cases of thyroid eye disease are associated with hyperthyroidism? 

Answer 48

90%

Question 49

What myopathies can affect extraocular muscle muscles? 

Answer 49

1. OPMD (progressive symmetric ptosis/diplopia from AD mutation PABPN1 gene) 2. CPEO (mitochondrial myopathy with progressive symmetric involvement of  extraocular muscles and eyelids). Strangely, subjective diplopia is often absent.