Endocrine Abstracts

Background: Myasthenia gravis and thyroid disease can sometimes create diagnostic confusion because the two may have similar clinical features and may also co-exist in the same individual.

Case: A 68 years male, was seen in the Neurology clinic with drooping of his left eyelid, first noticed 8 months prior, worse in the evenings. There were no other complaints. He had history of type2 diabetes, and Graves’ disease. On examination, he appeared to have ptosis of his left eyelid; eye movements and visual field examination being normal. There was fatigable diplopia on sustained upward gaze. Fundoscopy was normal. The remaining neurological examination was unremarkable, except for slight fatigue in shoulder abduction and neck flexion. Reflexes were symmetrical but suppressed distally. The symptoms seemed consistent with myasthenia gravis. He was commenced on Pyridostigmine which made him feel significantly better. However, routine blood tests, Myasthenia antibodies, and nerve conduction tests done to elucidate the diagnosis were normal on two occasions. This was against the initial picture of myasthenia gravis. On subsequent review he had developed proptosis in the right eye that was almost certainly secondary to Graves’ disease. It was challenging now to determine whether he had ptosis on the left side, or just proptosis on the right. He did not have any fatigable diplopia or ptosis on sustained upward gaze this time, nor limb fatigue. MRI head showed features of thyroid eye disease and normal optic nerves.

Conclusion: Thus, what he was noticing over the past year was progressive right eye proptosis rather than ptosis in the left. He was referred to the Endocrine clinic and is now on Carbimazole and awaiting Ophthalmology review.