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Describe the pupillary light reflex pathway.
ON to optic tract to brachium of superior colliculus synapsing in the pretectal nucleus the to bilateral EWN to CN3. Parsympathetic innervation from CN3 splits in anterior cavernous sinus pass through SO with inferior division of CN3. In orbital apex it synapses in ciliary ganglion then traveling with fibers going to IO to posterior ciliary nerves then to pupillary sphincter.
Define route of Sympathetic innervation of Iris Dilator
Hypothalamus synapse in cilospinal of budge ascends via sympathetic chain ganglion along lung apex to internal carotid then synapse in the superior cervical ganglion at angle of the jaw/carotid bifurcation. Sympathetics run with CN6/carotid in cavernous sinus then join nasocilliary of V. In orbital apex pass ciliary ganglion without synapsing t to the globe via long cilliary nerve to dilator muscle.
Dx of Anisocoria in dim light
- miotics drop- Pilocarpine
What is the work up of Anisocoria in dim light if the dilator muscle is working properly?
- cocaine test then if both eyes dilate then it is physiologic
- if >1mm anisocoria= Horners syndrome. Then determine if it is 1st/2nd order or 3rd order.
- Hydroxyamphetamine= both eye dilate=1st/2nd order
- 3rd order small pupil unchanged
How does Apraclonidine work in anisocoria work up?
Use anisocoria in dim or bright light?
Why does it work?
- Dim light
- Apraclonidine does not affect normal pupil. It only affect sympathetic deinnervated pupils. It causes dilation of the miotic eye indicating a horners.
How does hydroxyamphetamine work?
It dilates a normal pupil and a 1st/2nd order horners. It doesnt affect a 3rd order lesion due to degeneration of the nerve terminal.
congential horners is caused by
Horners in childhood is caused by
- birth trauma
- neuroblastoma from sympathetic chain in chest
painful horners/ HA altered taste/amaurosis indicates
carotid artery disection
Anisocoria worse in bright light what is the work up?
pilocarpine ---pupil constriction= adie tonic pupil
- IF NO CONSTRICTION then
- 1% pilocarpine ---pupil constriction=3rd nerve
- no constriction with 1%= pharmacological mydriasis
Adie tonic is caused by
Key exam finding?
other exam findings
- postganglionic parasympathetic damage-denervated iris sphrinter
- segmental iris atony
- decrease reflexes
- orthostatic hypertension
cause of light near dissociation
- Dorsal Midbrain
- Arygll Robertson pupil Tertiary syphllis
- 3rd nerve aberrant reinnervation
- Peripheral neuropathy
- severe retinal/ON dz
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