A 34 year old woman presents with a drooping left eyelid for 1 day. She also experienced difficulty in speaking, swallowing and keeping her head up. The symptoms become progressively worse during the course of the day.

Close questioning reveals a history of several episodes of drooping of an eyelid with blurred vision over the past 2 years, with varying intensities.

Her medical history is otherwise unremarkable, and she is not on any drugs.