Q: What is Peek sign?


Answer: Myasthenia gravis causes weakness, predominantly in bulbar, facial, and extra-ocular muscles.

The peek sign is manifestation of orbicularis fatigue. On lid closure to command, the orbicularis muscle initially may achieve lid apposition; however, as the patient continues to try to keep the eyes forcefully closed over a minute, the orbicularis oculi fatigues, and sometimes the lids separate to show a rim of sclera, with the patient appearing to "peek" at the examiner. With profound orbicularis fatigue, the cornea may become visible.

The peek sign can also be seen with VII nerve palsies.