see also: [[Mydriasis]], [[miosis]], [[Diplopia]], [[anisocoria]], [[Cranial nerve palsies]], [[Relative afferent pupillary defect|RAPD]], [[Prévost's sign]], [[Eye exam]] see: [deranged physiology - examination of pupil reactivity](https://derangedphysiology.com/main/required-reading/neurology-and-neurosurgery/Chapter%204622/examination-pupil-reactivity-and-diameter-cn-ii-iii) #OSCE #Neuro #tables #trauma > [!key points] Clinical pearls > - presence of spontaneous eye movements excludes brainstem pathology as cause of coma > - horizontal movements or eyes are coordinated by *contralateral hemisphere* via ipsilateral pons (the right hemisphere instructs the left pons to look right) ; therefore: > - in hemispheric cortical pathology, the eyes will look *towards* the lesion > - in pontine pathology, they will look *away* from the lesion > - vertical movements of the eyes are coordinated by both hemispheres ## Bilateral miosis (pinpoint) | cause | description | | ------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | bilateral pontine lesion (eg haemorrhage) | damage to descending sympathetic fibres | | bilat thalamic lesion | damage to descending sympathetic fibres | | opiate intoxication | | | [[organophosphates\|organophosphate poisioning]] | excess parasymathetic | | barbituate poisioning | | | rare causes: | - neurosyphilis (bilat [Argyll robertson pupil](https://en.wikipedia.org/wiki/Argyll_Robertson_pupil)<br>- diabetic neuropathy<br>- bilat horner's syndrome (eg bilat [[carotid and vertebral artery dissection\|carotid dissection]] or neck trauma, massive thalamic or pontine damage | ## unilateral miosis | cause | description | | ------------------ | --------------------------------------------------------------------------------------------------------------------- | | horner's syndrome | | | sympathetic damage | any level:<br>- ipsilateral thalamic lesion<br>- ipsilateral pontine lesion<br>- ipsilateral sympathetic chain lesion | ## Bilateral mydriasis | cause | description | | ---------------------------- | -------------------------------- | | brainstem herniation | end stages (likely irreversable) | | bilat midbrain lesion | eg basilar artery infarct | | bilat 3rd nerve damage | eg severe base of skull fracture | | severe global brain injury | eg due to hypoxia | | [[Anticholinergic toxicity]] | | | sympathomimetic drugs | | | [[Serotonin Syndrome]] | | ## unilateral mydriasis | cause | description | | ------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------- | | midbrain lesion | ipsilateral damage to the Edinger Westphal nucleus of 3rd nerve (resulting in loss of parasympathetic input to ipsilateral eye) | | [[Head trauma radiology#Brain Herniation types\|uncal herniation]] | stretch of 3rd nerve across the petroclinoid ligament | | direct trauma to eyeball | eg traumatic mydriasis | ## pupil deviation See [[Prévost's sign]]: conjugate eye deviation in patients with acute stroke. Also see: [[vertigo#HINTS exam|Vertigo → HINTS exam]] as can also have gaze deviation here > I probably should have called this “**gaze deviation**” or eye deviation to be more accurate, and it isn’t really a “pupil” finding, but I find it helpful to include here because one might notice it when they are checking the pupils. horizontal movements or eyes are coordinated by *contralateral hemisphere* via ipsilateral pons (the right hemisphere instructs the left pons to look right) ; therefore: - in hemispheric cortical pathology, the eyes will look *towards* the lesion - in pontine pathology, they will look *away* from the lesion # pupil syndromes ## Argyll Robertson pupil ![[Pasted image 20240802222018.png]] ## Horner Syndrome aka "oculosympathetic paresis" ipsilateral ptosis, [[miosis]] (constricted pupil), and decreased facial sweating (anhidrosis) and apparent enophthalmosis (inset eyeball) - caused when sympathetic trunk nerves are damaged ![[Pasted image 20241225133310.png|ptosis, miosis, and anhidrosis on the left]] **Causes** *central* - [[Brain Tumours]] - [[Multiple Sclerosis]] - syringomelia - encephalitis - [[carotid and vertebral artery dissection#internal carotid dissection]] - lateral medullary syndrome - Wallenberg's syndrome due to dissection of the [[carotid and vertebral artery dissection|vertebral artery]] or obstruction of the posterior inferior cerebellar artery - ataxia - sensory deficits of face and cranial nerves ipsilaterally -- loss of pain and tem sensation - nystagmus associated with [[vertigo]] - *preganglionic* -- has anhidrosis of face - cervical rib trraction - thyroid carcinoma - goitre - bronchogenic lung carcinoma of superior fissure ==[[Pancoast tumour|pancoast tumor]]== - blunt trauma to base of neck - [[Thoracostomy]] complication - thoracic aortic aneurysm - *postganglionic* -- no anhidrosis - cluster headache - [[Headache|migraine]] - [[Cerebral venous thrombosis|cavernous sinus thrombosis]] - [[Acute Otitis Media|middle ear infection]] - sympathectomy - nerve blocks eg cervical block, stellate ganglion or interscalene block ## Marcus gunn (aka [[Relative afferent pupillary defect|RAPD]]) ## Odd pupil shapes **dyscoria** - any abnormality in the shape of the pupil **synechia** - iris adheres to cornea or lens (anterior or posterior synechia). can be caused by trauma, [[Eye infections#Iritis / uveitis / choroiditis|iritis / uveitis]], or iridocyclititis, can lead to [[Glaucoma]]. can affect how pupil reacts to light ![[Pasted image 20241108184504.png]] intraocular inflammation can lead to adhesions btwn iris and lens (posteior synechiae). **coloboma** - defect in eye structure causing misshapen pupil **corectopia** - pupil is off-centre **anisocoria** - unequal pupils **oval pupil** - ==concerning for angle-closure [[Glaucoma]]!== **Tear drop pupil** - in setting of ocular trauma, concern for [[eye trauma#Globe rupture]] ## pupils diagram (not very good) ![[Pasted image 20241108183114.png]]