Comparative study on the value of accessory examinations in the diagnosis of ocular myasthenia gravis

Abstract

Objective To compare the sensitivity and specificity of ice test, neostigmine test and single fiber electromyography (SFEMG) in the diagnosis of ocular myasthenia gravis (OMG), so as to establish an appropriate process for the diagnosis of OMG. Methods A total of 116 patients with newly onset ptosis and/or diplopia were detected by ice test, neostigmine test and SFEMG. Patients were followed up for 6 months to observe the disease changes and experimental treatment effects. Results Apart from patients whose diagnosis was in doubt or lost to follow - up, and who were diagnosed as generalized myasthenia gravis (GMG), the definite diagnosis was finally made in 81 patients, including 21 OMG patients and 60 patients with ptosis and/or diplopia caused by other diseases. The sensitivity of ice test for diagnosis of OMG was 95.24% (20/21), and specificity was 98.33%(59/60). The sensitivity of neostigmine test for diagnosis of OMG was 90.48% (19/21), and specificity was 85% (51/60). The sensitivity of SFEMG for diagnosis of OMG was 95.24% (20/21), and specificity was 80% (48/60). Among 3 tests, only specificity was found significant difference ( χ 2 = 5.232, P = 0.022). The specificity of ice test was better than that of neostigmine test ( χ 2 = 5.707, P = 0.017) and SFEMG ( χ 2 = 6.023, P = 0.014). Conclusions The ice test achieved high sensitivity and specificity in the diagnosis of OMG. The combination of ice test, neostigmine test and SFEMG may have important clinical value for the early diagnosis of OMG. DOI: 10.3969/j.issn.1672-6731.2016.10.008