Approach to Diplopia Flashcards
What is monocular diplopia?
Perception of double images when viewing with one eye.
What are rare causes of bilateral monocular diplopia?
Cerebral diplopia, polyopia (can see hundreds of images), and palinopsia (ie trails).
What tool can confirm a monocular cause of visual disturbances?
Pinhole occluder.
What should be emphasized in the history for binocular diplopia evaluation?
Prior diplopia episodes
Childhood strabismus
Recent or remote head trauma.
Diplopia with vertical and torsional (with lower image tilted) orientation suggests involvement of which muscle?
Superior oblique muscle.
What is the likely localization of pure vertical diplopia?
Brainstem or cerebellar pathology.
What does diplopia with reading or near tasks suggest?
Dysfunction of convergence, involving cranial nerve III or medial rectus muscle.
What does diplopia at distance indicate?
Dysfunction of divergence, suggesting lateral rectus muscle or cranial nerve VI involvement.
Diplopia onset characteristic
Diplopia is always sudden in onset (its either there or it isn’t).
Diplopia/ocular misalignment not changing with gaze direction is classified as?
Comitant, suggesting congenital strabismus (or skew deviation if vertical).
What does diplopia that varies with gaze direction indicate?
It indicates incomitant diplopia, often due to extraocular muscle dysfunction.
What is the diagnostic yield of neuroimaging in isolated fourth, pupil-sparing third, and sixth nerve palsies?
Low diagnostic yield in older patients with vascular risk factors.
What percentage of patients over 50 with one vascular risk factor had other causes for nerve palsies?
10% had causes like neoplasm, infarction, and giant cell arteritis.
What causes skew deviation?
Injury to the utricular-vestibular-ocular pathway in brainstem or cerebellum.
How does skew deviation differ from cranial nerve IV palsy?
Vertical misalignment decreases by 50% or more in supine position compared to upright.
Which EOM muscle does the superior branch of Cranial Nerve III innervate?
Superior rectus.
What actions are performed by the superior rectus muscle?
Elevation, intorsion, adduction.
Which cranial nerve branch innervates the medial rectus muscle?
III (Inferior branch).
What action is performed by the inferior rectus muscle?
Depression, extorsion, adduction.
Which muscle performs extorsion, elevation, and abduction?
Inferior oblique.
What actions are performed by the superior oblique muscle?
Intorsion, depression, abduction.
What key feature distinguishes INO from medial rectus muscle weakness?
Adduction with convergence is preserved in INO.
What structure is affected in INO?
Medial longitudinal fasciculus.
What does the medial longitudinal fasciculus connect?
Ipsilateral sixth nerve nucleus (pons) contralateral third nerve nucleus (midbrain).
What symptoms occur with injury to the third nerve nucleus on one side?
In addition to ipsilateral CN3 palsy, there may be contralateral ptosis and supraduction weakness.
What symptoms can accompany diplopia when third nerve fascicles are affected in the midbrain?
Ataxia, tremor, or hemiparesis (HAT).
Isolated fourth nerve palsies are frequently caused by what condition?
Trauma.
What can cause isolated sixth cranial nerve palsies to be falsely localizing?
Stretching of the nerve due to increased intracranial pressure.
What anatomical structures does the sixth cranial nerve pass through?
Clivus, Dorello canal, petrous ridge, cavernous sinus.
What test is used to suggest MG by improving ocular symptoms?
Ice pack test applied for 2 minutes.
What is eyelid curtaining?
Lifting one eyelid causes the fellow eyelid to droop.
What is the Cogan eyelid twitch sign?
The upper eyelid jerks up once or twice upon returning to primary gaze from downgaze, especially if after a period of prolonged upgaze.
Which extraocular muscle is most commonly involved in thyroid ophthalmopathy?
Inferior rectus muscle.
What causes restriction of eye movements in thyroid ophthalmopathy?
Progressive edematous changes of the orbital musculature.
What does idiopathic orbital myositis result in?
Painful, isolated extraocular muscle dysfunction.
Which cranial nerve is most commonly affected by idiopathic orbital myositis?
The third cranial nerve.
What condition can cause orbital inflammation with painful diplopia similar to Idiopathic Orbital Myositis?
IgG4-related disease (an immune-mediated fibro-inflammatory condition) and Orbital Lymphoma (typically older patients w/ recurrent or progressive symptoms).
What condition may resemble idiopathic orbital inflammation in older patients?
Orbital lymphoma may resemble idiopathic orbital inflammation in older patients.
What is crucial when instructing patients using an eye patch?
Ensure the eyelid under the patch is fully closed to prevent corneal injury.
