When should myasthenia gravis be considered as a potential diagnosis in a patient with eye movement weakness?

Myasthenia gravis should always be considered as a potential diagnosis when evaluating a patient with eye movement weakness. This is because myasthenia gravis can present with a wide variety of symptoms that may mimic other conditions, including IIIrd, IVth, or VIth cranial nerve palsies. The variability and fluctuating nature of muscle weakness in myasthenia gravis can make it challenging to fit the symptoms neatly into the patterns typically seen with cranial nerve palsies. Therefore, even if the weakness appears to fit a specific cranial nerve pattern, myasthenia gravis should still be considered.