Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hemifacial Spasm ?
    ### Response:
    Hemifacial spasm is a neuromuscular disorder characterized by frequent involuntary contractions (spasms) of the muscles on one side (hemi-) of the face (facial). The disorder occurs in both men and women, although it more frequently affects middle-aged or elderly women.
    