Diagnostic value of repeated ice tests in the evaluation of ptosis in myasthenia gravis

Abstract

Abstract TITLE: Diagnostic Value of Repeated Ice Tests in the Evaluation of Ptosis in Myasthenia Gravis PURPOSE: To determine the repeatability and diagnostic value of the ice test in the evaluation of ptosis in myasthenia gravis (MG). DESIGN: Retrospective review. METHODS: Twenty-six patients with ptosis related to MG and 38 controls with ptosis other than MG were included. All patients were tested with the ice test 2 times on separate days in the afternoon. The margin reflex distance (MRD) was measured before and immediately after 2-minute application of ice on the eyelids. The ice test was judged positive if there was an improvement of at least 2.0 mm MRD after the ice test. 'Equivocalwas defined by improvement of MRD from at least 1.0 mm to less than 2.0 mm after the ice test. RESULTS: Repeated ice tests showed an agreement of 61.5% in MG, and 97.4% in nonmyasthenic ptosis. Repeated ice tests increased the positive predictive value by 2.7%, the negative predictive value by 11.6% and sensitivity by 26.9% compared to a single test. Among the patients with repeatedly negative test results, 63.7% of those who showed equivocal results at least once turned out to be MG. Of those with repeated non-equivocal negative results, nobody turned out to be MG. There was no statistically significant difference of the results of the ice test between ocular MG and generalized MG (p = 0.562). CONCLUSIONS: The repeatability of the ice test was 61.5% in myasthenic ptosis. Repeated ice tests enhanced the sensitivity of the test by 27% compared to a single test. Patients with an equivocal negative result had a 64% chance to have MG.