Ice Test for the Diagnosis of Myasthenia Gravis

Sorot Wutthiphan M.D.

ABSTRACT Objective : To study the effectiveness of the ice test for the diagnosis of ocular myasthenia.

Design : Prospective study

Subjects and Methods : Twenty two patients with suspected myasthenia gravis including 9 patients with ptosis, 9 patients with strabismus and 4 patients with combined ptosis and strabismus were tested with rest test, ice test and Prostigmin test. Palpebral fissure and ocular deviation were measured before, immediately after a 2-minute rest, 2-minute application of ice to the eyelid and 45 minutes after intramuscular injection of Prostigmin. One or more millimeters of improvement in palpebral fissures was considered a positive result.

Results : Of the 9 patient with ptosis, 6 had positive rest test, ice test and Prostigmin test, 3 had hegative rest test, ice test and Prostigmin test. Only one of the 9 patients with strabismus had a 25 prism diopter (PD) shift in alignment from the Prostigmin test and none had improvement of ocular deviation from the rest test and the ice test. All of the 4 patients with combined ptosis and strabismus had positive rest test, ice test and Prostigmin test for ptosis. The mean pre-test ocular deviation was 18.75 PD (range : 16-25). The mean change was 0 PD from the rest test, 3.75 PD from the ice test and 18 PD from the Prostigmin test.

Conclusions : The ice test is safe, short, specific, cheap and sensitive test for the diagnosis of myasthenic ptosis.

Thai J Ophthalmol 2000 ; July-December 14(2) : 103-108.