Facial muscle spasm, also known as facial muscle twitching, refers to painless contraction of the orbicularis oculi muscle. The orbicularis oculi muscle includes the upper and lower lid muscles. Facial muscle spasms usually start in the lower lid muscles and then extend to the upper lid, showing painless contractions that may even extend to the lower part of the face and appear as corner-of-mouth contractions. The contraction usually increases during stress and disappears during sleep. In very severe cases of facial muscle spasm, the entire eye may not open and the eyelid may droop, which can sometimes resemble myasthenia gravis ptosis and may be misdiagnosed as myasthenia gravis. Therefore, if the upper eyelid cannot be opened, you should go to the hospital and let a professional doctor distinguish whether it is facial myospasm or myasthenia gravis, and the treatment is different for it.