Evaluation and validation of sustained upgaze combined with the ice-pack test for ocular myasthenia gravis in Asians.

The accuracy of the ice-pack test for diagnosing myasthenia gravis (MG) has been reported to be excellent, however, the sensitivity is low in patients with mild ptosis which is common in Asians who have absent or low double eyelid folds. Herein, we performed the ice-pack test after sustained upgaze and tested its validity for diagnosing MG. The study included 30 newly diagnosed MG patients with ptosis (median age 47 years, range 2-87 years) and 30 controls with ptosis other than MG (median age 58 years, range 5-83 years). All MG patients initially presented with ptosis and/or diplopia; 26 patients had purely ocular MG while 4 patients progressed to generalized MG. All patients performed the new ice-pack test after sustained upgaze for 2 min. The ice-pack test was judged positive if there was an improvement of at least 2 mm of margin reflex distance compared to the level of ptosis before (conventional ice-pack test) or after (new ice-pack test) sustained upgaze. Subgroup analysis was performed according to the level of ptosis. The conventional test showed 43.3% sensitivity and 100% specificity for diagnosing MG, while the new ice-pack test achieved 73.3% sensitivity and 96.7% specificity, respectively. In patients with mild ptosis, the sensitivity and specificity for diagnosing MG were 27.8% and 100% by the conventional test, and 72.2% and 96.7% by the new ice-pack test, respectively. The new ice-pack test combined with sustained upgaze was more sensitive for diagnosing MG, particularly in patients with mild ptosis which is common in Asians.