Use of the Cogan lid twitch to identify myasthenia gravis.

BACKGROUND To evaluate the reliability of the Cogan lid twitch (CLT) test in a neuro-ophthalmology clinic. METHODS CLT testing was performed on adult patients presenting to the neuro-ophthalmology clinic by the neuro-ophthalmologist. The patients were instructed to look straight ahead, up, down, and straight ahead again. The upper eyelids were carefully evaluated immediately following this movement for the presence of a brief upward twitch of the upper eyelid, which would indicate a positive CLT test. The test was repeated as needed. We evaluated the findings from the ophthalmologic examination along with results of available tests, such as serologic findings, MRIs, and CTs. RESULTS Of 117 patients evaluated, 24 had myasthenia gravis (MG), and 18 of these patients had a positive lid twitch. Of the 98 patients who did not display a positive Cogan twitch, 6 had MG. We calculated the specificity of the CLT to be 99%, with a sensitivity 75% and false-positive rate 1%. CONCLUSION The CLT test is a specific and sensitive test to use in a neuro-ophthalmology clinic to evaluate for MG.