What is the probable diagnosis in a patient with dilated pupil not responsive to 1% pilocarpine
Looking at the options one by one: Diabetic 3rd nerve palsy: Third nerve palsy due to anv reason will result in mvdriasis (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 manitests 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 mav 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 Pharmacological block: Drugs like atropine block the muscarinc receptors present on the pupil. As the receptors cannot work, even high doses of Pilocarpine cannot produce miosis. Ref-Goodman and Gillman 12/e p1777
Diabetic 3rd nerve palsy
Adie's tonic pupil
Uncal herniation
Pharmacological block
Autonomic nervous system