* Drooping of the eyelid is called ptosis and may occur in the setting of numerous neurologic conditions (including myasthenia gravis, oculomotor palsy, and Horner's syndrome) because innervation of the eyelid can be disrupted at many different levels along the neuroaxis.
Any disruption to sympathetic or 3rd nerve innervation of the eyelid can produce ptosis and local eyelid abnormalities can produce ptosis, as well.
Place the finding of ptosis in the context of the rest of the clinical evaluation to determine its cause.
In myasthenia gravis, prolonged upgaze will enhance ptosis and placement of an ice bag over the eyelids (typically for two minutes) will improve neuromuscular transmission and, as a result, lessen ptosis.