Neuroland: 64. Diplopia

Diplopia!

Charles Wheatstone (1802 – 1875)

Royal Medal of the Royal Society for binocular vision explanation

"...cause of the single appearance of objects seen by both eyes..."

2) EOM anatomy

3) Approach Is it true diplopia, or is it a blurry vision? - mono vs bi - other neurologic symptoms - CNs palsies - screen GCA & thyroid disease

4) Mono vs Bi Monocular "close one eye does not resolve" - pinhole, if normal - refractory; abnormal - cortical - dry eyes & refractory error Binocular "close either eye solves problem"

5) Other neurological symptoms

Yes, help to localize lesion

No, isolated diplopia

6) Isolated diplopia

a. How are the two images positioned? How does distance affect diplopia?

b. what field makes it worse? or improve it?

c. moving head correct the vision?

d. pain w/ eye movement?

7) CN palsies

- causes vasculopathy & tumors, specifics

aneurysm (CN III), congenital trauma (CN IV), cranial pressure (CN VI)

8) Double vision CN III: DV, others: droopy eyelid, pupil asymmetry CN IV: DV vertical or diagonal CN VI: DV horizontal INO: DV horizontal changing sides

9) Oculomotor palsy

For further localization of CN III

1. Nuclear lesion - bilateral incomplete ptosis 2. Complete or partial lesion of the nerve trunk - sup & inf divisions 3. Superior division of the third nerve - palpebrae & SR 4. Inferior division of the third nerve - all other muscles of CN III
9.1. CN III palsy- DV, others: droopy eyelid, pupil asymmetry

9.2. CN III palsy- DV, others: droopy eyelid, pupil asymmetry

9.3. CN III palsy

- DV, others: droopy eyelid, pupil asymmetry

9.4. Nuclear oculomotor nerve palsy- bilateral ptosis + L CN palsy features (SR palsy)

9.5. CN III palsy Trunk lesion involving sup and inf visions - sup div SR and palpebra - inf div rest

10) Trochlear palsy- torsion degree> Maddox rod test> fundus photo (fovea is in lower 1/3 of optic disc)- trochlear palsy versus skew deviation> skew deviation improves w/ laying down (vestibular system issue)

10.1. CN IV - 3-step test

10.2. CN IV- primary gaze hypertropia at the affected side - worsening at contralateral gaze - tilt head to the same side to increase hypertropia *contralateral dorsal exit