Hemifacial spasm (HFS) is a neurological disorder manifested by twitching on one side of the face due to involuntary contractions of the eyelid and other facial muscles. It usually begins gradually ...
"The reason we pay close attention to benign essential blepharospasm is because it can be confused with a hemifacial spasm, muscle contractions of the eyelid and cheek on one side of the face.