Ptosis is commonly associated with which condition?

• A. Parkinson's disease
• B. Myasthenia gravis
• C. Guillain-Barré syndrome
• D. Multiple sclerosis

Answer: (B)

Drooping of the eyelid reflects weakness of the eyelid muscles from impaired neuromuscular transmission, especially when the weakness is fatigable and worsens with use. Myasthenia gravis is a classic autoimmune disorder where antibodies attack acetylcholine receptors at the neuromuscular junction, reducing signal transmission to muscles. This causes fluctuating, fatigable weakness that commonly affects the ocular muscles, so ptosis (and diplopia) are typical early signs. The droop often improves with rest or with acetylcholinesterase inhibitors, reinforcing the link to a neuromuscular junction problem.

Other conditions can involve the eyes, but the pattern of fatigable ptosis is most characteristic of myasthenia gravis. For example, Parkinson’s disease can have eyelid drooping due to facial hypomotility but is not defined by fatigable eyelid weakness; Guillain-Barré syndrome usually presents with rapidly progressive, symmetric weakness and areflexia with possible cranial nerve involvement, not a hallmark fatigable ptosis; multiple sclerosis features optic neuritis or internuclear ophthalmoplegia rather than a classic Ptosis-predominant presentation.