RESUMEN
BACKGROUND: Diagnosis of myasthenia gravis is difficult, especially when the disease is restricted to ocular muscles. It is a well-known observation that myasthenic ptosis improves with cold and based on this, the ice pack test has been used as a tool in its differential diagnosis. The aim of the study is to investigate the diagnostic value of ice pack test as a preliminary test in the differential diagnosis of myasthenia and to find out the percentage of positivity and negativity of the ice pack test. MATERIALS AND METHODS: The study included patients seeking treatment for ptosis in a tertiary care center in Kerala. All patients were subjected to the ice pack test. Evaluation of patients was made by recording the marginal reflex distance (MRD). MRD was recorded before and after the application of ice pack, and an improvement of more than 2 mm was considered positive. Patients were divided into two groups: (1) those who had ptosis and features suggestive of myasthenia; and, (2) those who had ptosis but no features of myasthenia. Patients of both groups were subjected to relevant investigations and the diagnosis of myasthenia was established. RESULTS: Ice cold test was positive in 48 (96%) patients and negative in two patients of the myasthenia group. In the control group, 6 (12%) patients had a false positive ice cold test and in the remaining 44 patients (88%), ice cold test was negative. CONCLUSION: Ice pack test has a high specificity and sensitivity in the differential diagnosis of myasthenic ptosis.