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The ice pack test is a useful bedside test that can aid in the differentiation of myasthenia gravis (MG) from other conditions. It is cheap, safe, and very quick to perform as it can be carried out at the bedside in approximately 3–5 minutes. According to a recent study pertaining to myasthenic diplopia, the sensitivity of this test was 76.9% for the 5-minute application and the specificity was 98.3% with no false-positives reported. The test consists of the application of ice to the eyes for 2–5 minutes, ensuring that the ice is covered to prevent ice burns. If positive, the patient no longer has the characteristic ptosis of MG. The results of the test can be deemed positive with an improvement of the patient's diplopia or a raise of 2 mm of the palpebral fissure following the removal of the ice pack. The physiological theory behind the test is very simple; it is thought that by cooling the tissues, and more specifically the skeletal muscle fibers, the activity of the acetylcholinesterases are inhibited. Reference: Kearsey C, Fernando P, D'Costa D, Ferdinand P. The use of the ice pack test in myasthenia gravis. JRSM Short Rep. 2010;1(1):14. Published 2010 Jun 30. doi:
