Diagnosis and localising HORNER SYNDROME |cocaine, apraclonidine, hydroxyamphtamine, phenylephrine

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Diagnosis and localisation of HORNER SYNDROME |cocaine, apraclonidine, hydroxyamphtamine, phenylephrine
The video talks about the pharmacological tests for horner syndrome.
For the diagnosis of horner syndrome we have the cocaine test and the apraclonidine test . after diagnosis for localisation of the lesion, we use 1% hydroxyamphetamine test and phenylephrine test
#hornersyndrome
#neet #usmle
#pupil
#neuroophthalmology

Опубликовано:

28 июн 2024

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Комментарии : 15

@debigdogk9563 Год назад

The best video explaining such a difficult topic for e to understand. Thank you ❤❤❤❤❤

@aishwaryabhattacharya8215 10 месяцев назад

Why in apraclonidine there is supersensitivity enough for dilation even in 1st and 2nd order neuron damage but not when phenylephrine is given ?

@Nirajace1997 6 месяцев назад

Same doubt +1 ma'am can u reply to the comment? Is it related to chronicity of nerve damage??

@InsightOphthalmology 6 месяцев назад

I apologise for the late reply That's a really interesting questions. On exploring the literature I found that there is a lot of ambiguity on this. What I understand is that the amount of supersensitivity that develops( ie the increase number of alpha1 receptors )is much more in type 3 horners( postganglionic) than type 1or 2 Now, phenylephrine 1% has a alpha1 agonist action. In type 3 horners with greater number of alpha1 receptors, phenylephrine causes dilation, but it isn't able to do so with the amount supersensitivity that develops in type 2/1 Moreover, apraclonidine is a weak alpha one agonist and a strong alpha2 agonist. Alpha 2 inhibits sympathetic presynaptic terminals( i.e causes decrease in release nor epinephrine). This dual mechanism somehow helps it act in both pre and post ganglionic horner. Quite ambiguous but it's missing in literature. Let me know if you have any other explanation.