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Pharmacology

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Autonomic Nervous Systems

Question
9 out of 75
 

What is the probable diagnosis in a patient with a dilated pupil not responsive to 1 % pilocarpine?

(AIIMS Nov 2011)



A Diabetic 3rd nerve palsy

B Adie's tonic pupil

C Uncal herniation

D Pharmacological block

Ans. D Pharmacological block (Ref: Goodmall and Gilman 12th/1 777)

Effect of different pharmacological agents on pupil

Clinical Setting

Drug

Pupillary Response

Normal

Phenylephrine

Mydriasis

Pilocarpine (1 %)

Miosis

Pilocarpine (0.05-1 %)

No miosis

Cocaine

Mydriasis

Opioids (oral or i.v.)

Miosis

Homer's syndrome

Cocaine (4-10%)

No dilation

Preganglionic

Hydroxyamphetamine 1 %

Dilation

Postganglionic

Hydroxyamphetamine 1 %

No Dilation

Adie's tonic pupil

Pilocarpine 0.05-0.1 %

Miosis

Atropinized pupil

Pilocarpine (1 %)

No miosis

Now looking at the options one by one:

Diabetic 3rd nerve palsy: Third nerve palsy due to any reason will result in mydriasis (because oculomotor nerve supplies constrictor pupillae). However, as only nerve supply is destroyed but the receptors remain intact, so it will respond to pilocarpine (1 %) and thus miosis will occur.

Adie's tonic pupil: It manifests as denervation supersensitivity. Normal pupil responds to 1 % Pilocarpine but does not contract with highly diluted solution like 0.05-0.1 %. However, in Adie's pupil due to supersensitivity of receptors, even this diluted solution may also result in constriction.

Uncal herniation: It result in pressure on third cranial nerve and presents as dilated pupil but it will respond to Pilocarpine as the receptors are intact.

Pharmacological block: Drugs like atropine block the muscarinic receptors present on the pupil. As the receptors cannot work, even high doses of Pilocarpine cannot produce miosis.

Autonomic Nervous Systems Flashcard List

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