[Ptosis--clinical differential diagnosis]

When examining a patient with ptosis the first question to be answered is whether the condition is a simple constitutional variant or a symptom heralding disease. Local diseases of the eyelid may lead to pseudoptosis. The three major disease categories to be considered are: myopathies preferentially affecting the eye muscles; impaired neuromuscular impulse transmission at the motor endplate (myasthenia gravis, botulism); and lesions of the somatomotor (third cranial nerve) and visceromotor (sympathetic) nerve fibers innervating the eyelid muscles. The correct diagnosis may be suspected in the light of a detailed patient history and associated signs on general and neurological examination. Additional investigations may be needed to confirm the diagnosis.