Ptosis: A sign of myasthenia gravis

Ptosis is a sign of a number of diseases, most of which are benign. Julie Falardeau, MD, of the Casey Eye Institute, Portland, OR, described how ophthalmologists can avoid overlooking myasthenia gravis, which can be associated with serious morbidity and mortality.

"It is important to be aware of myasthenia gravis because, as an ophthalmologist, you will be the one to examine that patient with ptosis," she said.

"Myasthenia gravis has ocular signs in about 75% of cases and the ocular signs are the first manifestations in over 90% of patients," she said.

Eighty-five percent to 90% of these patients will have systemic symptoms within 2 years, which underscores the importance of making an early diagnosis and referring to a neuro-ophthalmologist or neurologist, Dr. Falardeau said.

The hallmark of myasthenia gravis is variability of symptoms and fatigue. The ptosis, which can be unilateral or bilateral, usually increases as the day progresses in these patients but can be induced in a clinical setting by having the patients gaze upward for an extended period. She advised looking for a Cogan lid twitch, which is often present. When these patients are asked to gaze downward and then rapidly upward, a subtle overshoot of the lid, the Cogan lid twitch, may be seen.

The sleep test, the ice test, the Tensilon test and prostigmin also can assist in establishing a diagnosis of myasthenia gravis.

Dr. Falardeau urged ophthalmologists to conduct a comprehensive evaluation of patients who present with ptosis and to include myasthenia gravis in the differential diagnosis.

"Myasthenia is a serious urgent condition," she concluded.