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Ice Pack Test in OMG!



-Myasthenia gravis is a post synaptic autoimmune disorder due to failure of neuromuscular transmission resulting from binding of autoantibodies to proteins involved in signalling at the NMJ.

-OMG is where weakness is clinically isolated to the periocular muscles (extraocular muscles, LPS and orbicularis oculi).

- Ocular muscles are involved in 97% of patients during disease.


FEATURES:

-Ptosis.

-Diplopia.

-Fluttering of ptotic eyelid observed during eye movements (Lid Hopping)

-Cogan's lid twitch: Quick overshooting upward movement followed by a down-drift of the upper lid after the patient performs a saccade back to primary position from looking down.

-Peek Sign: On prolonged forceful closure of the eyes , they drift open to reveal sclera or cornea in spite of the patient's attempt at keeping them closed.

-Simpson's sign: Provocative tests with looking upward or to one side for 60 seconds gives clue to diagnosis.


DIAGNOSIS:

-Sleep Test.

-Ice Pack Test.

-Edrophonium/Neostigmine test.


WHAT IS THE MECHANISM OF ACTION IN ICE-PACK TEST?

-Icepack is placed over the patient's closed eyelids for 2minutes.

-The test is considered positive when the upper eyelid elevates by atleast 2mm following application of ice.

-Cooling reduces acetylcholine esterase activity which increases the amount of available ACh available at the NMJ.

-This promotes the efficiency of ACh in eliciting depolarization at the motor end plate.


TREATMENT:

-Acetylcholinesterase inhibitors.

-Corticosteroids.

-Other immunomodulators.

-Plasma exchange (Plasmapheresis) and IV Immunoglobulins.



www.ophthalmobytes.com⁣

Image from Rajan Eye Care Hospital⁣

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