In myasthenia gravis, which sign is most commonly the initial presenting symptom?

• A. Proximal limb weakness first
• B. Memory loss
• C. Hearing loss
• D. Ptosis and diplopia

Answer: (D)

In myasthenia gravis, weakness that worsens with use (fatigability) is the hallmark. The most common early manifestation is involvement of the eye muscles, so the first sign people notice is ptosis (drooping eyelids) and diplopia (double vision). This happens because the extraocular muscles are exercised continuously and are highly sensitive to the reduced efficiency at the neuromuscular junction caused by ACh receptor autoantibodies. The weakness tends to fluctuate and worsen with sustained activity and improve with rest or acetylcholinesterase inhibitors, which fits the pattern seen with ocular symptoms. Memory loss and hearing loss aren’t typical features of MG, and while proximal limb weakness can develop, it’s not usually the initial presenting sign.