Acquired Ptosis-Myogenic Myasthenia Gravis

A 35-year-old woman noticed that herright upper eyelid started to droop asthe day progressed. She denied otherocular problems, including decreasedvisual acuity, pain, or diplopia. The patienthad no generalized fatigue, difficultyin swallowing, or weakness ofher arms or legs.

Some variability in the patient'sptosis was found. A less severe ptosisof the left upper eyelid was noted aswell (A). Fatigue of the levator palpebrae muscle was identified when the ptosis worsened after thepatient looked up for several minutes.

In a young woman, variable ptosis that worsens with fatigue raises the suspicion of myastheniagravis. Edrophonium chloride was administered intravenously; this acetylcholinesterase inhibitorincreases the amount of acetylcholine available for binding to postsynaptic receptors by blockingthe action of acetylcholinesterase. The effect of this diagnostic drug lasts only a few minutes; therefore,the ptosis needs to be significant enough to allow reliable appraisal of improvement.

After edrophonium chloride was administered, the ptosis improved (B), and ocular myastheniagravis was diagnosed. This autoimmune disease that affects the neuromuscular junction oftenhas serious ramifications; it can initially involve the ocular muscles and cause ptosis, diplopia, orblurred vision. Variability in muscle strength and fatigability of voluntary musculature are key clinicaldiagnostic characteristics of this disease.

The patient was referred to a neurologist, who initiated the antiacetylcholinesterase medication,pyridostigmine. Low-dose corticosteroids or other immunosuppressives may be helpful in patientswho do not respond to pyridostigmine.