iatroX Rounds #3
The clues
- 1
A 28-year-old woman presents to her GP with intermittent double vision and drooping of her left eyelid noticed over the last month.
- 2
She describes that her symptoms are much less noticeable when she first wakes up but become significantly worse by the evening.
- 3
There is a past medical history of autoimmune thyroid disease. She mentions that her voice sounds increasingly nasal after talking for long periods.
- 4
Clinical examination reveals fatigable ptosis during sustained upward gaze for 30 seconds and weakened power in proximal limb muscles.
- 5
Repetitive nerve stimulation during electromyography shows a progressive decline in the amplitude of the compound muscle action potential.
- 6
Blood tests demonstrate the presence of serum autoantibodies directed against the postsynaptic nicotinic acetylcholine receptors.
Myasthenia gravis is an autoimmune disorder of the neuromuscular junction where antibodies interfere with signal transmission. It is characterized by fluctuating skeletal muscle weakness that typically worsens with repetitive use and improves with rest.
- Diurnal variation with symptoms worsening throughout the day
- Fatigable ptosis and diplopia are common initial presentations
- Bulbar involvement may lead to a nasal voice or swallowing difficulties
- Strong association with thymic hyperplasia or thymoma
for education and entertainment. not medical advice.