see: [Rosen - Diplopia](x-devonthink-item://F5F468BD-60B6-4EB5-9A6C-6531F75BF3A7), [Dunn Abnormal eye movements](x-devonthink-item://75745D60-FB73-4380-A380-943C6CEDDAF3), [Rosen Ophthalmology](x-devonthink-item://43FF5B61-AC39-42AF-AADD-6BB6C2B8800B) see also: [[Visual fields]], [[Cranial nerve palsies]], [[pupil exam]], [[anisocoria]], [[pupil exam#pupil deviation|pupil deviation]] #opthal > [!key points] > - in CN III palsy, consider compressive lesion (eg aneurysm), especially if dilated pupil > - ==orbital / musclar causes of diplopia (eg thyroid eye disease, myasthenia gravis) can be confused with cranial nerve palsies== **Ophthalmoplegia** = the paralysis or weakness of the eye muscles ![[Pasted image 20240308152354.png|muscle dysfunction, sx, and examination findings for each oculomotor cranial nerve palsy]] ![[Pasted image 20240308152535.png|cardinal movements of the eyes]] ![[Pasted image 20240308153833.png| diplopia algorithm]] ![[Pasted image 20240308153955.png| management algorithm]] # Causes of diplopia ![[Pasted image 20240922191757.png]] **binocular diplopia** - ocular nerve palsies - *III* - diagonal diplopia on upward lateral gaze - *IV* - vertical diplopia on downward medial gaze - *VI* - horizontal diplopia on lateral gaze - impairment of normal globe movement - ocular muscle entrapment (eg blow out fracutre of orbital floor with inferior rectus entrapment) - thyroid eye disease (inferior rectus) - masses - swelling - gaze palsies - nuclear -- oculomotor reflex reduced - *Internuclear ophthalmoplegia* — white matter connecting nuclei, seen in [[Multiple Sclerosis]] and vertebrobasilar (cerebellar and brain stem / [[Stroke#posterior circulation]]) stroke - supranuclear palsy (eg progressive supranuclear palsy a/w PKD, FTD, alzheimers) -- oculomotor reflex intact - peripheral [[vertigo]] (due to ocular skew) - neuromuscular diseases eg [[myasthena gravis]] - occipital cortical disease -- usually homonymous hemianopia also present **monocular diplopia** (present when only one eye open) - uncommon - usually due to distortions of cornea or lens - *corrects with pin hole testing* - ==retina== issues DO NOT correct with pin hole testing ## CN III palsy see also [[Cranial nerve palsies#CN III palsy|Cranial nerve III palsy]] causes: - trauma (herniation of temoral lobe through tentoral opening) - ischaemic (*especially diabetes*) - vascular - *PCA aneurysm* - [[myasthena gravis]] ## diplopia causes table #tables | Cause | Issues | Distinguishing features | | ------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | | basilar artery thrombosis | - brainstem ischaemia <br>- ↑ mortality | [[vertigo]], dysarthria, CN involvement, [[Stroke]] risk factors | | basilar meningitis | | headache, meningism, fever | | aneurysm | enlarging aneurysm directly compress cranial nerve | CN III palsy with pupillary involvement | | [[carotid and vertebral artery dissection\|vertebral artery dissection]] | dissection → vertebrobasilar ischaemia | - neck pain, vertigo | | [[myasthena gravis]] | Abs agains ACh nicotinic receptors | fluctuating muscle weakness, ptosis, diplopia<br>worsen with activity; improve w/ rest | | [[Alcohol-related disease\|Wernicke encephalopathy]] | thiamine-dependent metabolic failure | nystagmus, ataxia, ALOC, ophthalmoplegia<br>alcoholism and nutritional deficiencies | | orbital apex syndrome, [[Cerebral venous thrombosis\|cavernous sinus]] process | inflammation or infection in the orbital apex or cavernous sinus → oculomotor cranial nerve deficit | CN III, IV, or VI palsy, retro-orbital pain, conjunctival injection, periorbital or facial numbness | | brainstem tumor | | skew deviation - vertical diplopia, internuclear ophthalmoplegia | | Miller-Fisher syndrome ([[Guillain-Barré syndrome\|GBS]]) | Abs to cranial nerve ganglioside | ophthalmoplegia, ataxia, areflexia | | [[Multiple Sclerosis]] | demyelinating lesions | internuclear ophthalmoplegia | | thyroid myopathy ([[thyrotoxicosis\|Graves disease]]) | autoimmune myopathy | proptosis, restriction of elevation and abduction of eye, other signs of graves disease | | ophthalmoplegic [[Headache#migraine\|Migraine]] | | ipsilateral headache, CN III palsy |