A thiy five year old female has proximal weakness of muscles, ptosis and easy fatigability. The most sensitive test to suggest the diagnosis is:

Answer is C (Edrophonium test): Edrophonium test is the most sensitive test to suggest the diagnosis of myasthenia gravis amongst the options provided. Proximal weakness of muscles, ptosis and easy fatigability suggests a diagnosis of Myasthenia Gravis. Edrophonium (Tensilon) test is a highly sensitive test with 85% sensitivity in ocular and 95% sensitivity in systemic myasthenia. The diagnosis of MG is highly probable if Edrophonium test is unequivocally positive. Note Conventional (EMG) is not a sensitive diagnostic test for MG. The conventional needle EMG is usually normal in patients with MG although ceain findings may indicate probability of MG. Conventional EMG evaluation in MG serves mostly in excluding other causes of weakness like motor neuron disease, neuropathy or myopathy