Enhancement of contralateral ptosis on passively holding an eyelid in mitochondrial myopathy resembling myasthenia gravis.

Ptosis has long been recognized as a presenting sign of myasthenia gravis, and the appearance of ptosis or increasing ptosis with passive lid elevation of opposite eye is a useful bedside diagnostic test for this disease. We describe a patient whose ptosis worsened in either eye when the examiner passively held the opposite eyelid. She was initially thought to have myasthenia gravis, but ultimately it was discovered her ocular findings were caused by a mitochondrial myopathy.